Subcontract Report

NREL/SR-520-47289

December 2009

Economic On-Grid Solar Energy 

via Organic Thin Film Technology

28 September 2007 – 27 October 2008

D. Laird, J. Bernkopf, S. Jia, J. Krieg, S. Li, 

C. McGuiness, J. Rossier, M. Storch, R. Tipnis, 

R. Tuttle, B. Woodworth, and S. Williams

Plextronics, Inc.

Pittsburgh, Pennsylvania
National Renewable Energy Laboratory

1617 Cole Boulevard, Golden, Colorado 80401-3393

303-275-3000 • www.nrel.gov

NREL is a national laboratory of the U.S. Department of Energy

Office of Energy Efficiency and Renewable Energy

Operated by the Alliance for Sustainable Energy, LLC

Contract No. DE-AC36-08-GO28308

Subcontract Report

NREL/SR-520-47289

December 2009

Economic On-Grid Solar Energy 

via Organic Thin Film Technology

28 September 2007 – 27 October 2008

D. Laird, J. Bernkopf, S. Jia, J. Krieg, S. Li, 

C. McGuiness, J. Rossier, M. Storch, R. Tipnis, 

R. Tuttle, B. Woodworth, and S. Williams

Plextronics, Inc.

Pittsburgh, Pennsylvania

NREL Technical Monitor: Bolko von Roedern

Prepared under Subcontract No. NAT-7-77015-06
This publication was reproduced from the best available copy

Submitted by the subcontractor and received no editorial review at NREL

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iii 

Table of Contents

Project Summary ........................................................................................................................................... 1 

Milestone #1.................................................................................................................................................. 2 

Milestone #2.................................................................................................................................................. 5 

Milestone #3.................................................................................................................................................. 6 

Milestone #4.................................................................................................................................................. 7 

Milestone #5.................................................................................................................................................. 8 

Milestone #6.................................................................................................................................................. 9 

Milestone #7................................................................................................................................................ 11 

Milestone #8................................................................................................................................................ 12 

Milestone #9................................................................................................................................................ 14 

Milestone #10.............................................................................................................................................. 15 

Milestone #11.............................................................................................................................................. 17 

Milestone #12.............................................................................................................................................. 18 

Milestone #13.............................................................................................................................................. 20 

Milestone #14.............................................................................................................................................. 21 

Milestone #15.............................................................................................................................................. 25 

Milestone #16.............................................................................................................................................. 26 

Milestone #17.............................................................................................................................................. 27 

Milestone #18.............................................................................................................................................. 30 

Milestone #19.............................................................................................................................................. 31 

Milestone #20.............................................................................................................................................. 32 

Milestone #21.............................................................................................................................................. 34 

Milestone #22.............................................................................................................................................. 35 

Milestone #23.............................................................................................................................................. 36 

Milestone #24.............................................................................................................................................. 37 

Milestone #25.............................................................................................................................................. 38 

Milestone #26.............................................................................................................................................. 39 

Conclusions and Outlook ............................................................................................................................ 40 

 
iv
1

Plextronics, Inc. was awarded the U.S. Department of Energy’s (DOE) Solar America Initiative (SAI) 

PV-Incubator contract in 2007. The goal of the program was to take its Organic Photovoltaic (OPV) 

technology from laboratory-scale and demonstrate a pathway to 3MW manufacturing capacity (~2010) 

and 7c/kWh LCOE by 2015. The program supports the Solar Energy Technology Program (SETP)

charter as follows: 

Project Summary

1. Driving commercialization of novel, low-cost thin film PV technology via development of 

commercial high performance OPV inks to enable production of modules.

2. Systematic, quantitative evaluation of technological options on the pathway toward achieving grid 

parity with conventional sources of power. 

3. Demonstrating an OPV module development line and utilizing it as a pathway toward establishing 

high volume manufacturing facility that will eventually contribute to U.S. installed domestic 

capacity for PV systems.

Plextronics employed a three-pronged approach to meet the Incubator goals:

1. Driving device efficiency via materials development

2. Improved stability and lifetime via device design and process development

3. Translating laboratory-scale performance to large-area modules via establishment of a pilot 

manufacturing-development line (D-Line) to evaluate manufacturing-worthy processes

Table 1 below summarizes Plextronics’ deliverables for the program; because the program was driven by 

deliverables, this final report largely summarizes the individual deliverables.

Table 1: Deliverables for PV-Incubator Program

Phase # Deliverable

1 Report on baseline lab-cell (Efficiency = 5.1% (NREL-certified); Lifetime = 700 hours at 2 sun; 85 °C) and 

module (Efficiency = 0.8% (internally tested)) performance

2 Report on lab-cell (Efficiency = 5.4% (internally tested)) performance

3 Report on LCOE of OPV module 

4 Quarterly report

5 Deliver a Lab-Cell sample (Efficiency = 5.4% (NREL-certified))

6 Report on design and fabrication of pre-production prototype module (Efficiency = 1% (internally tested))

7 Report & update on LCOE model

8 Quarterly report

9 Report on prototype manufacturing

10 Report on lab-cell performance (Lifetime > 3723 hours)

11 Report & update on LCOE model

12 Deliver a prototype module (Efficiency = 1.5% (NREL-certified); Lifetime > 2000 hours)

13 Stage-gate review and progress report

14 Quarterly report

15 Quarterly report

16 Lab-cell with 5.8% efficiency (NREL-certified)

17 Lab-cell with 5,776 hours lifetime

18 Module with 3.5% (active area) Efficiency (NREL-certified)

19 Module with 5,000 hours Lifetime

20 Module with 2% active area efficiency-0.82% total area efficiency (NREL-certified)

21 Module with 1000 hours light-soaking (100% duty cycle) near 25 °C, >1.6% final active area efficiency (0.66% 

total area) (NREL-certified)

22 Data comparison after 1000 hours Lifetime (outdoor)

23 Demonstrate 9s6p Module, verify >1.5% active area efficiency (0.70% total area efficiency) (NREL-certified)

24 Module with 500 hours light-soaking (100% duty cycle) Near 25 °C, initial efficiency >2.5%, final efficiency 

>2% (1.2% and 0.93% total area efficiency) (NREL-certified)

25 Module with 500 hours light-soaking near 85 °C 85% RH, Stability after 200 hours to be >50% of original, test to 

be conducted on module with >2% active area efficiency (0.93% total area efficiency)

26 Draft Final Report

27 Final Report 

PHASE I

PHASE II
2

MILESTONE #1: Report Summarizing Baseline Lab-Cell and Module Performance. 

KEY METRICS: Efficiency = 5.1% (NREL-certified) for lab-cell and 0.8% (internally tested) for 

module; Lifetime (lab-cell) = 700 hours. 

1.1 

1.1.1 

Lab-cell devices

Devices were fabricated on 50mm × 50mm patterned ITOcoated glass substrates (~ 20 ohm/square). 

Efficiency

Figure 1 shows 

the design layout of our lab-cell (4 cells per substrate). 

Substrates were cleaned by sonication in acetone and 

isopropanol, dried and UV-Ozone treated. A 30 nm holetransporting layer was spin-coated on top of the ITO, and 

annealed. The active layer, based on proprietary p- and ntype semiconductors, was spin-cast and annealed. The 

cathode (typically Ca/Al) was thermally deposited (10-6

mbar). Devices were encapsulated in nitrogen glove box 

with a cavity glass with desiccant. Cell area measurements 

conducted on cells sent to NREL vary between 0.089 and 

0.096 cm2 and are used for internal efficiency calculations. Figure 2 shows the data for an OPV cell 

certified at NREL to exhibit 5.1% efficiency. 

Figure 2: I-V and EQE spectrum of OPV device certified to 5.1% at NREL

1.1.2 

Plextronics defines lifetime as the duration over which an OPV device or module diminishes to 80% of its 

‘stabilized’ power output (or power conversion efficiency), normalized by the illumination intensity 

(lamp variation or decay) under ~ 1 Sun Xe-arc lamp with (or converted to) 50% duty cycle. Devices 

were tested outdoors (roof-top - at our labs in Pittsburgh) and were kept at either a 45 degree or 5 degree 

angle with respect to the horizon facing south with a direct exposure to the sun from the horizon to the 

Lifetime

Figure 1: Plextronics’ lab-cell design
3 

zenith. The devices were periodically tested under solar simulation (AM1.5G, 100 mW/cm2). The device 

parameters like short circuit current density (JSC), open circuit voltage (VOC), fill factor (FF) and 

efficiency were monitored over time. Following lifetime data show two representative devices based on 

P3HT:PCBM and proprietary active layers (Figure 3). The test exhibits devices operating above T90 

after more than 750 hours. 

Figure 3: Un-accelerated roof-top outdoor lifetime data for (a) P3HT:PCBM (left) and (b) Proprietary active 

layer (right) devices. T80 is given on the efficiency vs. time plot.

1.2 

Devices were fabricated on 150mm × 150mm patterned 

ITO-coated glass substrates (~ 20 ohm/square) with metal 

grid. Substrates were initially pre-cleaned in SRD machine 

and then cleaned in large ultrasonic baths in acetone and 

isopropanol, dried and UV-Ozone treated. A 30 nm holetransporting layer was spin-coated on top of the ITO, and 

annealed. The photoactive layer is a blend of regioregular 

poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 

butyric acid methyl ester (C60-PCBM) with a ratio 1.2:1. 

These active layers were spin cast on large Headway 

Research PWM32 spinner and annealed in glove box. The 

cathode (typically Ca/Al) was thermally deposited (10-6

mbar). Devices were encapsulated in nitrogen glove box 

with a cavity glass with desiccant. 

OPV Modules

Figure 4 shows the module that comprises of 54 × 2 cm2 cells, totaling 

108 cm2 active area. 

External quantum efficiency (EQE) measurements were done with chopped monochromatic light using an 

Oriel 250 W Quartz Tungsten Halogen Source, a SR540 optical chopper (17 Hz), an order-sorting filter 

wheel and a Cornerstone 130 1/8m Monochromator System with focusing optics. Short-circuit 

photocurrent from OPV device was detected with a SR570 low-noise current preamplifier and SR830 

DSP dual phase lock-in amplifier. The incident light intensity from a monochromator was measured with 

a calibrated Si photodiode (Hamamatsu S1336-44BK). Encapsulated devices were characterized under 

standard AM1.5G test condition in ambient conditions. An 8” Thermo Oriel solar simulator with the 

AM1.5G filter assembly and power intensity of 78 mW/cm2 was utilized to test the modules. The 

intensity of the light source was adjusted using an NREL-certified KG-5 filtered silicon cell to achieve the 

measured current under AM1.5G. The short-circuit current was adjusted for the spectral mismatch factor 

(M) between the solar spectrum and the light. Current voltage data were collected using a Keithley 2400 

source measure unit. Figure 5 depicts the performance of internally tested 150mm × 150mm OPV 

module measured to have an active area efficiency of 1.07%. 

Figure 4: Plextronics’ OPV module

0 150 300 450 600 750 7.0

7.5

8.0

8.5

9.0

9.5

Jsc (mA/cm2)

Time (H)

0 150 300 450 600 750 0.4

0.5

0.6

0.7

0.8

0.9

Voc (V)

Time (H)

0 150 300 450 600 750 0.3

0.4

0.5

0.6

0.7

FF

Time(H)

0 150 300 450 600 750 0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

T80

% Eff

Time(H)

0 150 300 450 600 750 7.0

7.5

8.0

8.5

9.0

9.5

Jsc (mA/cm2)

Time (H)

0 150 300 450 600 750 0.4

0.5

0.6

0.7

0.8

0.9

Voc (V)

Time (H)

0 150 300 450 600 750 0.3

0.4

0.5

0.6

0.7

FF

Time(H)

0 150 300 450 600 750 0.0

0.5

1.0

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2.0

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4.0

T80

% Eff

Time(H)

0 150 300 450 600 750 7.0

7.5

8.0

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Jsc (mA/cm2)

Time (H)

0 150 300 450 600 750 0.4

0.5

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0.9

Voc (V)

Time (H)

0 150 300 450 600 750 0.3

0.4

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FF

Time (H)

0 150 300 450 600 750 0.0

0.5

1.0

1.5

2.0

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3.0

3.5

4.0

T80

% Eff

Time(H)

0 150 300 450 600 750 7.0

7.5

8.0

8.5

9.0

9.5

Jsc (mA/cm2)

Time (H)

0 150 300 450 600 750 0.4

0.5

0.6

0.7

0.8

0.9

Voc (V)

Time (H)

0 150 300 450 600 750 0.3

0.4

0.5

0.6

0.7

FF

Time (H)

0 150 300 450 600 750 0.0

0.5

1.0

1.5

2.0

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3.0

3.5

4.0

T80

% Eff

Time(H)

a) b)

0 150 300 450 600 750 7.0

7.5

8.0

8.5

9.0

9.5

Jsc (mA/cm2)

Time (H)

0 150 300 450 600 750 0.4

0.5

0.6

0.7

0.8

0.9

Voc (V)

Time (H)

0 150 300 450 600 750 0.3

0.4

0.5

0.6

0.7

FF

Time(H)

0 150 300 450 600 750 0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

T80

% Eff

Time(H)

0 150 300 450 600 750 7.0

7.5

8.0

8.5

9.0

9.5

Jsc (mA/cm2)

Time (H)

0 150 300 450 600 750 0.4

0.5

0.6

0.7

0.8

0.9

Voc (V)

Time (H)

0 150 300 450 600 750 0.3

0.4

0.5

0.6

0.7

FF

Time(H)

0 150 300 450 600 750 0.0

0.5

1.0

1.5

2.0

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3.5

4.0

T80

% Eff

Time(H)

0 150 300 450 600 750 7.0

7.5

8.0

8.5

9.0

9.5

Jsc (mA/cm2)

Time (H)

0 150 300 450 600 750 0.4

0.5

0.6

0.7

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0.9

Voc (V)

Time (H)

0 150 300 450 600 750 0.3

0.4

0.5

0.6

0.7

FF

Time (H)

0 150 300 450 600 750 0.0

0.5

1.0

1.5

2.0

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3.0

3.5

4.0

T80

% Eff

Time(H)

0 150 300 450 600 750 7.0

7.5

8.0

8.5

9.0

9.5

Jsc (mA/cm2)

Time (H)

0 150 300 450 600 750 0.4

0.5

0.6

0.7

0.8

0.9

Voc (V)

Time (H)

0 150 300 450 600 750 0.3

0.4

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FF

Time (H)

0 150 300 450 600 750 0.0

0.5

1.0

1.5

2.0

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3.0

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4.0

T80

% Eff

Time(H)

a) b)
4

Figure 5: I-V and Power-Voltage data of 150mm × 150mm OPV module; Intensity = 78 mW/cm2
5

MILESTONE #2: Report On Lab-Cell Performance.

KEY METRICS: Efficiency = 5.4% (Internally Tested).

The devices were fabricated on 50mm × 50mm substrate as per the procedure described earlier. The 

active layer comprises of proprietary p- and n-type materials. The devices were tested under a Xe-arc 

solar simulator with AM 1.5G filter. The intensity of the light source (100 mW/cm2

) was adjusted using 

an NREL-certified KG-5 filtered silicon cell to achieve the measured current under AM1.5G. The shortcircuit current was adjusted for the spectral mismatch factor (M) between the solar spectrum and the light. 

Figure 6 shows the data for an internally-tested lab-cell device which was measured to have an efficiency 

of 5.51%. 

Figure 6: J-V characteristics of device under AM1.5G 100 mW/cm2 (left) and in dark (right).

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

-10

-8

-6

-4

-2

0

Jsc(mA/cm2) 2 Voc(V) FF E(%)

9.56 Jsc(mA/cm2) 0.86 0.67Voc(V) 5.51 FF E(%)

9.56 0.86 0.67 5.51

AM1.5G 100 mW/cm2

Jsc ( mA/cm2 )

Voltage ( V )

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 10-6

10-5

10-4

10-3

10-2

10-1

100

101

102

103

In dark

Current density ( mA/cm2 )

Voltage ( V )
6

MILESTONE #3: Report on LCOE of OPV Module. 

This report was an explanation of the Levelized Cost of Electricity (LCOE) model used by Plextronics to 

justify its SAI projections. It included a discussion of the calculation methodology as well as the 

assumptions that went into the calculations. 

Solar modules based on OPV materials currently have a shorter lifetime than their silicon and thin filmbased counterparts currently on the market. Because of this, these modules cannot simply be installed and 

left to produce power as more traditional silicon modules can be. Instead, the OPV modules will require 

periodic replacement to maintain their output. The calculation of LCOE needs to be modified to account 

for the additional cost of these replacements. Similarly, because the modules are degrading faster and 

then being replaced, the production function is very different from traditional silicon technologies that 

have a slow, steady degradation over time. Instead, the production associated with OPV-based solar 

modules will have peaks associated with the installation of new modules followed by more rapid 

degradation until replacement when the production would experience another peak. Additionally, as OPV 

technology is progressing rapidly to higher efficiencies, the peak production level associated with the 

replacement will also increase over time. This report outlined the details of this module replacement 

model. 

3.1

The lifetime production of the system is measured by discounting each year’s production to a base year 

for comparison. To compare OPV with other competing technologies, we need to use the same period for 

comparison. While a silicon-based solar module can be put into service and will operate for 20 years or 

more before replacement is required, OPV will require the modules to be swapped out periodically to 

maintain the desired level of output. In our model, the frequency of replacement under this “swap out” 

model is determined by setting a minimum acceptable percentage of the original output. When the 

module’s output drops below this threshold, the module will be replaced.

Swap Out Model

The total lifetime output for a given project is found by combining the efficiency and degradation 

trajectories to obtain an overall production function for the solar farm being modeled. Figure 7 shows the 

characteristic “sawtooth” production function resulting 

from the swap out model we have employed for OPV. 

There are a number of features of this production 

function which warrant discussion. Most important, are 

the spikes in production associated with the swapping 

out of older modules with newer, more efficient ones 

(shown as dark bars). It can clearly be seen that the 

height of the peaks increases sharply in early years, 

mirroring the rapid rise in the module efficiency 

trajectory. Also, improved performance allows 

modules to operate longer before needing to be 

replaced. This is seen as an increase in the number of 

years between module replacements, corresponding to 

the dark bars in Figure 7. 

Though they are based on very different production 

models, comparing the results of our modeling with 

NREL’s Solar Advisor Model (SAM) can provide 

validation for the calculation methodology employed.

2007 2012 2017 2022 2027 2032 2037 2042 2047 2052 2057

Year

Production (kWh)

Figure 7: Annual production assuming 

module swap out at 50% of original 

output. Dark bars represent years of 

module replacement.
7

MILESTONE #4: Quarterly Report.

A report was submitted summarizing the deliverables to date. We also reported on internally measured 

lab-cell efficiency of 5.7%, and provided an update on the outdoor lifetime measurements on lab-cells 

(data from Figure 3) that were operating above T75 after more than 3800 hours of test. An examination 

of these roof-top data helped us determine that these devices undergo a “burn-in” of performance within 

the first 1500 hours of roof-top exposure. This burn-in typically reduces initial device efficiency by 20%. 

However, the devices then entered a very stable phase of operation in which the degradation of devices 

was significantly slowed. We termed this point ‘The initial stabilized cell efficiency’, which is used as 

the starting point for determining cell lifetime. Lifetimes of greater than 5000 hours were projected from 

such analysis. The proprietary active layer is a promising technology over the standard P3HT:PCBM 

control in regards to the higher efficiencies and comparable stability. Figure 8 shows the updated data 

from the outdoor testing of lab-cell devices.

Figure 8: Un-accelerated roof-top outdoor lifetime data for (a) P3HT:PCBM (left) and (b) Proprietary active 

layer OPV (right) devices. T80 is given on the efficiency vs. time plot.
8

MILESTONE #5: Deliver A Lab-Cell Sample.

KEY METRICS: Efficiency = 5.4% (NREL-certified). 

Plextronics’ internal testing of cells has been shown to be nearly identical to NREL test data for the VOC

and FF cell parameters. The ISC measurement, in which our data typically correlates to 0.95 – 1.02x of 

the NREL measured ISC, verifies a good correlation of our solar simulation with NREL data. The highest 

source of error between the two systems is cell area measurement which is a result of variations of 

shadow masking during cathode deposition. This comparison of device parameters between the two test 

systems gives us confidence in our internal efficiency measurements. Figure 9 shows NREL-certified 

data for I-V (left), and the EQE spectrum of the highest certified OPV device, respectively. The 

efficiency of 5.4%, was the world-record for the highest OPV lab-cell efficiency measured at that time.

Figure 9: I-V data of OPV device certified to 5.4% at NREL (left) and Normalized EQE spectrum from 

NREL (right)
9

MILESTONE #6: Report on Design and Fabrication of Pre-Production Prototype Module. 

KEY METRICS: Efficiency (active area) = 1% (internally tested). 

This report was a summary of the module modeling efforts between Plextronics and our consultant, Dr. 

Sean Shaheen from University of Denver. 

6.1 

The module modeling effort was being carried out as three components: a “back end” consisting of 

differential equations that solve for the series resistance of the individual devices as a function of their 

size and shape, a “front end” consisting of assembly of the complete module circuit layout and subsequent 

generation of J-V and power conversion efficiency characteristics, and an interface that will allow for 

simple input of module layout. At this time, the front end was complete, and was being used to test 

various scenarios of module design, especially with regards to the effects of variance in the individual 

device parameters, as discussed below. Work on the back end was underway. 

General Modeling Methodology

Figure 10 outlines the 

strategy. 

Figure 10: Flow-chart of the module modeling effort

6.2 

Plextronics has fabricated a 150mm × 150mm module with 108 cm2 of active area to achieve 1.07% 

efficiency under large format AM1.5 (78 mW/cm2

, KG-5 Si reference) solar simulation. This 

configuration was a first attempt at designing an OPV module based on spin-coating, in essence it is a 

scaled version of our prototype devices but with 2 cm2 individual pixels. There are 54 individual pixels 

all connected in series thus allowing for a high voltage module. The current champion data (

Module Performance and Analysis

efficiency of 

1.07%) are shown in Figure 11 as well as modeling fits on earlier device data (0.9%) which was studied

as a basis for this modeling work.

Figure 11: OPV Module performance

The circuit model used for each individual device on the module is shown in Figure 12 (left). Fitting of 

the simulation to preliminary data of a module consisting of 54 devices in series (hereafter referred to as 

Interface

“Back end”

Calculation of circuit

parameters from module layout

“Front end”

Generation of J-V characteristics

from circuit parameters and layout

-20 -10 0 10 20 30 40 50

10-5

10-4

10-3

10-2

Current density ( mA/cm2 )

Voltage ( V )

Jsc(mA/cm2) Voc(V) FF E(%) Pmax(mW)

7.43 24.75 0.25 1.07 90.22

0 5 10 15 20 25

0

2

4

6

8

10

0

20

40

60

80

100

Jsc ( mA/cm2 )

Voltage ( V )

 Power (mW)
10

54S) was also performed and is shown in Figure 12 (right). This particular module data exhibited very 

poor J-V characteristics. A “reverse curvature” can be seen for the J-V curve within quadrant IV. This 

can often be explained by a poor interface between the top metal electrode and the organic active layer in 

OPV devices. 

Figure 12: Equivalent circuit of the individual cell (left) and fitting of simulation to actual data.

IV

II I

III
11

MILESTONE #7: Report and Update on LCOE of OPV Module. 

This report documented the improvements made over the last quarter in order to increase the 

sophistication of Plextronics’ OPV LCOE model. Most of the modeling improvements were made in the 

module cost modeling that drives the LCOE calculation with some additional refinement in the 

projections for module lifetime, degradation and efficiency. Figure 13 outlines the various factors that 

contributed to the LCOE modeling effort during this quarter. 

Figure 13: Factors contributing to LCOE modeling effort

In addition to simply calculating the cost trajectory, the model also provides a number of features to allow 

it to be used for process analysis and optimization. One particularly useful feature of the model is the 

ability to automatically calculate a number of key metrics for the manufacturing process. The total 

megawatt output of the plant, the total capital expenditure, the capital expenditure per unit output, the cost 

per watt, and, as mentioned above, the cost per meter squared are all calculated on a year by year basis. 

These extend the model’s use to include strategic planning as it is now possible to compare different 

manufacturing processes on the basis of not only LCOE, but capital investment, manufacturing scale as 

well a number of other dimensions.

Taken together, Plextronics’ LCOE and manufacturing models provide the ability to explore a wide 

spectrum of manufacturing options and their effects on LCOE. The strength of the model lies in its 

ability to quantify the sensitivity of LCOE to its many constituent inputs. From exploring simple 

materials substitutions to complete process shifts, the model’s flexibility and comparative functionality 

allows for rapid iteration and quantification of different process flows. This can be used to rapidly 

identify key technology drivers for LCOE reduction. Through the use of the models, we have explored a 

number of materials and equipment choices, identifying key cost drivers and possible process technology 

improvements that would lead to significant cost reductions.

LCOE

Module 

Cost 

Trajectory

Module

Degradation

Trajectory

Module 

Efficiency

Trajectory

Accelerated

Testing

Real World 

Data

Updated

Internal 

Forecasts

Materials Equipment Labor

Cost

Yield

Throughput

Yield Depreciation

Cost

Direct Indirect

Cost

Other

•BOM

•Insolation

•O&M

 ...

Major Modeling Improvements

Lab

Cell

Efficiency

Lab Cell 

to

Module

Updated

Internal 

Forecasts
12

MILESTONE #8: Quarterly Report. 

As a part of this report, Plextronics gave an update on our OPV lab-cell and module performance as well 

as an update on our device lifetime and stability measurement program. 

8.1

We reported on our improved materials development effort that led to an internally measured efficiency 

of 6.1% (See 

Lab-cell update

Figure 14). 

Figure 14: J-V characteristics of device under AM1.5G (left) and in dark (right)

8.2 

We redesigned the layout of the OPV module in order to mitigate impact of observed non-uniformities 

along the periphery of the 150mm × 150mm glass substrates. These non-uniformities in layer thickness 

are caused by air and or nitrogen turbulence during the spinning operations. This helped to improved 

efficiency of the module from what was previously reported (see 

Module update

Figure 11). It should be noted that 

despite suppressing the effect of the non-uniformities of coated films on module performance, they still 

affect performance of several cells, namely those located near the corners of the substrate. We proposed 

to alter the spinning equipment in order to eliminate the presence of weak cells caused by nonuniformities of the organic layers. Figure 15 shows the efficiency data, measured internally at 1.88%, for 

the redesigned module. 

Figure 15: J-V and Power-Voltage data of 150mm × 150mm OPV module; Intensity = 100 mW/cm2

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

10-6

10-5

10-4

10-3

10-2

10-1

100

101

102

103

In dark

Current density ( mA/cm2 )

Voltage ( V )

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

-12

-10

-8

-6

-4

-2

0

2

Jsc(mA/cm2) Voc(V) FF E(%)

10.3 0.85 0.70 6.14

AM1.5G 100 mW/cm2

Jsc ( mA/cm2 )

Voltage ( V )

Voltage
13

8.3.

8.3.1 

Update on Plextronics’ OPV lifetime program

During this quarter, we made a significant addition to our OPV lifetime testing facilities, both indoor and 

outdoor setups. This included installation of a high intensity Xenon lamp to better simulate the solar 

spectrum; a temperature and humidity oven to simulate outdoor conditions and a compact, 32 device 

holder for lifetime testing. Furthermore, 36 additional holders were added for outdoor testing. We also 

placed an order for 10 channel all-weather lifetime tester and a photocurrent mapping instrument to carry 

out degradation studies on aged OPV devices. 

Facilities upgrades

8.3.2 

Outdoor rooftop testing of devices started at Plextronics rooftop in June 2007. As per Plextronics defined 

stabilized lifetime, these devices are performing very well with their stabilized power/efficiency still 

above T80. Some of the devices have shown to retain over 3% efficiency for >7000 hours.

Device lifetime

Figure 16 and 

Figure 17 show the un-accelerated roof-top lifetime data for devices made using P3HT:PCBM and 

proprietary active layer materials, respectively. Linear extrapolation of the decay curves project the 

lifetime to cross beyond 13000 hours. 

Figure 16: Un-accelerated roof-top outdoor lifetime data for P3HT:PCBM

Figure 17: Un-accelerated roof-top outdoor lifetime data for proprietary active layer materials

0 1000 2000 3000 4000 5000 6000 7000

1.2

1.4

1.6

1.8

2.0

2.2

2.4

T80

T75

% Eff

Time in Hours

0 2000 4000 6000 8000 10000 12000 14000

0.80

0.84

0.88

0.92

0.96

1.00

Normalized stabilized Eff

Stabilized Lifetime(Hrs)

 C

 Data1C

Sample η0 T80 η0 η0

s T80 η0s %decay per 1000h

P3HT:PCBM control 2.31% 2726 hrs 1.88 ~13000 1.7

0 1000 2000 3000 4000 5000 6000 7000

1.5

2.0

2.5

3.0

3.5

4.0

4.5

T80

T75

% Eff

Time in Hours

0 2000 4000 6000 8000 10000 12000 14000

0.80

0.85

0.90

0.95

1.00

1.05

Normalized stabilized Eff

Stabilized lifetime (Hours)

 B

 Linear Fit of Data2_B

Sample η0 T80 η0 η0

s T80 η0s %decay per 

1000h

PLEX PV-F3 4.25% 1200 hrs 3.41 ~13000 1.7
14

MILESTONE #9: Report on Prototype Manufacturing. 

This report documented the design of Plextronics prototype manufacturing development line (D-Line), 

including design options, vendor identification, and capital analysis. The D-line, is intended to be a 

learning tool for Plextronics through which we plan to translate our lab-scale OPV technology to large 

area (150mm × 150mm) modules, utilizing manufacturing worthy processes.

The D-line has been designed with focus on key areas within Plextronics process flow for OPV device 

fabrication using 150mm × 150mm modules. They are:

1. Module Design/Cell Architecture

• Establish in-house patterning capability to enable faster substrate design iteration that 

drives increased module efficiency. This leads to greater module power output and 

results in overall lower cost.

:

2. Organic Layer Application

• Evaluate solution processes that, in comparison to spin coating, have higher materials 

utilization, improved cycle (TAC) time, and are scalable to larger panel sizes (370mm × 

470mm and larger). This ultimately enables low-cost manufacturing.

:

3. Cathode Deposition

• Evaluate commercial scale PVD (thermal evaporation) equipment capable of operating in 

a continuous manner, as well as having the capability of running processes in parallel. 

This too results in low-cost manufacturing.

:

• Investigate alternate PVD processes such as sputtering and e-beam evaporation that have 

the potential for faster TAC time and/or are scalable to large panel sizes (370mm × 

470mm and larger).

4. Encapsulation

• Set-up a system capable of encapsulating 150mm × 150mm modules. Investigate 

methods of encapsulation that help prevent the degradation mechanisms of OPV device.

:

The areas of focus for the Pilot line and where they align with the process flow is shown in Figure 18.

Figure 18:Pilot Line: Technology Development Focus

Input

TCO Coated 

Glass

Scribe/Prep

Patterning of 

TCO Anode

Wash

Substrate

Surface Prep

Apply HTL

BakeHTL

Apply Active Layer 

Bake

Active Layer

Remove Layers

Deposit Cathode

Lead Connection

Test

Package/Ship

Encapsulate

Application of 

Organic Layers

Cathode Deposition

Encapsulation & 

Module Finishing

Module design / 

Cell architecture
15

MILESTONE #10: Report on Lab-Cell Performance. 

KEY METRICS: Lifetime > 3723 hours. 

10.1 

Figure 19

Device Design

shows the design of Plextronics organic solar cell on 50mm × 50mm glass substrate, viewing 

from the back side. The red lines indicate the ITO patterns on the glass substrate with long and short 

rectangles as anode and cathode leads, respectively. The red words and number indicate the information 

about the design and the order of 4 sides. 4 grey “L” shapes indicate the open area of shadow mask for 

cathode deposition. The square (black line) at the center of substrate indicates the cover glass for 

encapsulation. All active material on ITO outside of the central square needs to be removed by the laser 

ablator. As results, the overlap area of grey (cathode) and ITO inside the square produce a 3mm × 3mm 

active area of cells on each side of substrate. And the overlap of grey and ITO outside of cover glass is to 

secure the contact between ITO and cathode metal evaporated.

Figure 19: (left) Back side view of the design of Plextronics organic solar cells on 50mm × 50mm glass 

substrate. (right): Vertical structure of solar cell devices.

10.2 

A Xenon lamp (Atlas Specialty Lighting, PE240E-13FM) was used to generate both the temperature and 

light. The output designation of ‘1Suns’ is derived from adjusting the intensity of light falling on the 

devices to be such that a KG-5 cell placed in the same fixture would generate the same current it 

generates under standard AM 1.5G testing. The devices were connected to a data acquisition setup where 

an adjustable DC load maintains them at their maximum power point (MPP). The power output of the 

cells was continuously monitored over time. In addition, intermittent monitoring of the PV parameters 

such as Voc, FF, Jsc were performed. Note that an acceleration factor has not been determined for this 

system.

Accelerated 1 Suns/30°C continuous testing

Figure 20 (left) illustrates the output power of a lab-cell device that changes with time under ~1 sun Xelamp amp. The encapsulated devices were tested in ambient conditions with 100% duty cycle. The 

temperature of substrate was controlled at ~30oC. From this plot, the data can be divided into two distinct 

ranges. The first range is from 0 to about 450 hours and the devices shows quicker degradation in this 

range. After the initial degradation, the device starts to degrade slowly and stabilizes from ~500 hours. 

The data in stabilized range will be used to extrapolate the life time. Figure 20 (right) shows the 

normalized power output (based on the starting point of stabilized range) change with post-stabilized 

exposure time. The red dot line indicates the reference of 80% of initial stabilized power output of 

device. The stabilized data point was linearly fitted with black solid line. The crossed point of the black 

solid line and red dot line indicate a 2800 h life time for this particular device. It is called as the lifetime 

of T80 stabilized. The milestone requires 3723 hours lifetime of lab-cell devices under 1sun with 50% 

duty cycle. Since our device (demonstrating 2800 hours T80 stabilized) was tested under 1sun but 100% 

duty cycle, translation to 50% duty cycle could be 5600 hours. A multiplier of 2 was used for this simple 

translation
16

Figure 20:(left): The output power of a device under ~1sun changes with time. The temperature of the 

substrate was controlled at ~30oC; (right): Normalized output power changes with time after the output 

power stabilized
17

MILESTONE #11: Report and Update on LCOE of OPV Module. 

In this quarter, Plextronics further strengthened the connection between manufacturing choices and the 

impact on LCOE by allowing each defined process flow to include its own efficiency and lifetime, 

recognizing that process and materials choices may and, in many cases, will impact module performance. 

In addition to this significant change, several model inputs were refined and the LCOE model expanded,

to include competing technologies such as α-Si, CdTe, c-Si, and CIGS to provide a baseline that relies on 

the same calculation methodology for comparison purposes. The report explained the changes, including

examples of the calculations that these changes enable, and in doing so, demonstrated the results of these 

changes on the calculated LCOE for OPV. 

11.1 

Plextronics' LCOE model was expanded to mirror the concept of simultaneously tracking individual 

process flows introduced in the manufacturing cost model as part of milestone #7. Rather than looking at 

a single process, the LCOE model now included ten separate processes as well as entries for competing 

technologies. Previously, the LCOE model included process independent efficiency and lifetime 

trajectories while the module cost depended on the process flow and was calculated using the 

manufacturing cost model, as shown in

Linking Processing and Performance to Drive LCOE

Figure 21. This approach ignores the intimate connection 

between the choice of processing methods and the final performance of the device.

Figure 21: Previous LCOE Model Handling of Cost, Lifetime, and Efficiency Trajectories

To establish this connection, the methodology used in the model was changed to reflect the dependence of 

cost and performance on process and materials. As shown in Figure 22, the LCOE model has been 

modified such that the lifetime and efficiency trajectories are now associated with a given process and 

tracked independently. The result is a tool that yields a better understanding of the impact of module 

manufacturing choices on LCOE.

Figure 22: New LCOE Model Handling of Cost, Lifetime, and Efficiency Trajectories

} Efficiency

Cost

Lifetime

Process 1

Process 2

Process 3

Process 4

...

Process 10

Same for all Processes

Process Dependent

Efficiency

Cost

Lifetime

Process 1

Efficiency

Cost

Lifetime

Process 2

Efficiency

Cost

Lifetime

Process 3

Efficiency

Cost

Lifetime

Process 4

Efficiency

Cost

Lifetime

Process 10

Efficiency

Cost

Lifetime

Competing

Technologies

Efficiency

Cost

... Lifetime

Process 1

Efficiency

Cost

Lifetime

Process 2

Efficiency

Cost

Lifetime

Process 3

Efficiency

Cost

Lifetime

Process 4

Efficiency

Cost

Lifetime

Process 10

Efficiency

Cost

Lifetime

Competing

Technologies

...
18

MILESTONE #12: Prototype Gen1 Module Performance. 

KEY METRICS: Efficiency (active area) = 1.5% (NREL-certified); Lifetime = 2000 hours (80% of 

initial stabilized efficiency under ~ 1 Sun and at 50% duty cycle). 

Plextronics 150mm × 150mm OPV module consists of 54 identical cells (1 cm × 2 cm) that are organized 

in six parallel columns; each column contains 9 cells connected in series. The columns are electrically 

isolated so they can be measured independently and also allow various module configurations. The final 

configuration is achieved by external wiring; we chose, for development purposes, to connect either all 

columns in series (54s) or in a series/parallel (9s6p) configuration. The reported results in this report are 

for (54s) configuration.

12.1 

Figure 23

Module Efficiency

shows the performance of the OPV Module certificated at NREL as exhibiting 1.1% total area 

efficiency. This module was made from P3HT and PCBM blend and demonstrated 2.3% power 

conversion efficiency based on actual (47% total coverage) active area (1.1/0.47 = 2.3).

Figure 23 (left): I-V curves of recent module certification at NREL; (Right): Module with testing leads

12.2 

The lifetime testing of modules was carried out under a 

large-area, high-intensity Xe-lamp. The illumination 

intensity was tracked while the devices were placed on 

a temperature-controlled stage, with an adjustable DC 

load maintaining the devices at their maximum power 

point.

Module Lifetime

Figure 24 shows the normalized output power of the 

module after 500 hours; normalized by the input power 

decay of Xe-lamp irradiation. The increased scattering 

of normalized data is due to variations in the output of 

the Si photodiode and the module magnified by the 

normalization process. Application of a linear fit to 

the data gives a decay rate of 9.82% per 1000 hours (so 

the decay rate is ~5% per 1000 hours for 50% duty 

cycle). The lifetime is therefore greater than 4000 

hours based on Plextronics’ definition. 

0 200 400 600 800 1000

0.0

0.2

0.4

0.6

0.8

1.0

3070 100% Duty Cycle

NP on NB

Life Time (hours)

Figure 24: The normalized output power of 

the module based the decay of Xe-lamp 

illumination illustrating ~ 9.82%/1000h 

decay rate at 100% duty cycle translating 

to > 4000h of lifetime to T80 at 50% duty 

cycle with ~ 1 sun illumination.
19

Figure 25 shows the change of J-V characteristics (AM1.5G solar simulation) of the module after being 

illuminated under ~ 1 Sun Xe-lamp for 550 hours. The module performance is essentially unchanged, 

within the variation of test error, typically +/- 3%, strongly indicating that the module performance is very 

stable. The FF increased with light soaking, with a slight decrease in JSC and VOC. This led to essentially 

no significant change in the max power output (158 vs 153 mW). 

Figure 25(left): AM1.5G solar simulation J-V characteristics of module operated for 550 hours under ~1 Sun 

Xe-lamp, black-Freshly fabricated device; Red- 550 hours aged device. Spectral mismatch was applied to 

these efficiency measurements to correct the photocurrent; (right): Change in module parameters

Parameters Initial at 550 h

Jsc (mA/cm2) 0.15 0.14

Voc (V) 25.50 24.30

FF 0.37 0.43

E (%) 1.48 1.40

Pmax (mW) 155.80 153.00
20

MILESTONE #13: Stage-Gate Review. 

In July 2008, Plextronics underwent a stage-gate review for Phase I of the PV-Incubator project. We 

reported on all the deliverables which we met on schedule, or in most cases, well before the deadline. We 

presented our outlook for the Phase II of the program, as well as the long-term success of OPVs, 

including a pathway for commercial on-grids markets. 
21

MILESTONE #14: Quarterly Report. 

14.1 

We provided an update on both, lab-cell and module efficiency. 

Update on Efficiency

Figure 26 shows the data for lab-cell 

efficiency, internally measured at 6.32%. 

Figure 26: J-V data of lab cell OPV device tested internally, with and without aperture

Figure 27 shows the data for 150mm × 150mm module certified at NREL as exhibiting a total area 

efficiency of 1.56% (active area efficiency of 3.23%). 

Figure 27: J-V curve and performance data (certified by NREL) of 150 mm x 150 mm OPV module

14.2 

We provided an update on the stability of Module 3070 (data first discussed in Milestone #12, 

Update on Lifetime

Figure 24). 

Figure 28 (left) shows the normalized output power of Plextronics’ module (3070) after being normalized 

by the input power decay of Xe-lamp irradiation. The increased scattering of normalized data is due to 

stochastic variations in the lamp intensity, while the red arrow indicates the inflection of the power output 

0.0 0.2 0.4 0.6 0.8 1.0

-10

-8

-6

-4

-2

0

2

4

6

8

10

Photocurrent density ( mA/cm2 )

Voltage ( V)

3384-9-1

 No Aperture

 With Aperture

Parameters No aperture Aperture

Jsc mA/cm2 10.2 10.29

Voc,V 0.85 0.82

FF 0.72 0.75

Eff 6.24 6.32%
22

due to the module position change after JV measurement. Application of a linear fit to the data gives a 

decay rate of 9.82% per 1000 hours (the decay rate is ~5% per 1000 hours for 50% duty cycle). The 

decay rate observed would correspond to a lifetime of 5000 hours, measured with an initial efficiency of 

1.48%. Figure 28 (right) shows the change of J-V characteristics (AM1.5G solar simulation) of 

Plextronics’ module (3070) after being illuminated under ~ 1 Sun Xe-lamp for 648 and 1320 hours. The 

module performance is essentially unchanged, typically +/- 3%, within the variation of test error, and 

indicates that the module is very stable.

Figure 28(left): Normalized power output of module 3070 under Xe-lamp. This decay rate translates to > 

5000h of lifetime to T80 at 50% duty cycle with ~ 1 sun illumination. (right): AM1.5G solar simulation J-V 

characteristics of module 3070 operated for 648 and 1320 hours under ~1 Sun Xe-lamp. Data were smoothed 

(reduction of data points and removing of outliers) by interpolation in Origin software.

14.3 

14.3.1 

Update on work with University consultants

We have been working with its consultants at the Flexible 

Display Center (FDC) at Arizona State University (ASU), 

to develop a spray coat method for organic layer 

deposition in OPV fabrication. During the spray coating 

process the substrate rotates at low angular velocity while 

the swivel arm of the spray coating unit is moved across 

the wafer. The dynamics of the process is shown as a 

schematic drawing in 

Arizona State University

Figure 29. ASU will study the 

effect of different parameters such as solid content, 

solution dispense rate, scanning speed of atomizer, spin 

speed of substrate and spray pressure in the spray process,

on the film properties such as film thickness, uniformity 

and roughness. The performance would be compared to 

an OPV device prepared by spin coating.

ASU has optimized the spray coat process parameters on glass for Plextronics’ Plexcore® OC HTL 

material. The AFM data of surface roughness for spray coated HTL film on glass at different solvent 

dilution ratios is shown in Figure 30. Spray coated HTL film of thickness around 50 nm with root mean 

square surface roughness around 4nm and thickness non-uniformity of 12% was achieved. 

The inflection of the power output is due 

to the module position change after JV 

measurement. 

Figure 29: Schematic drawing of the 

dynamics in spray coating process
23

Figure 30: AFM profile of sprayed HIL film with thickness around 50nm at different dilution ratio (a) 

HIL:MeOH=1:5, R(rms)= 11nm, R(peak to valley)= 128nm, (b) HIL:MeOH:IPA=1:4:1, R(rms)= 7nm, 

R(peak to valley)= 74nm, (c) HIL:MeOH:H2O=1:0.5:3.5, R(rms)= 4nm, R(peak to valley)= 36nm.

ASU also worked on optimizing the spray coat process parameters on glass for OPV active layer material

from Plextronics. The spray coated film of OPV active material dissolved in mixture of solvents ‘A’ and 

‘B’ showed very high surface roughness. Mixing the solution with solvent ‘C’ further deteriorated the 

surface roughness, necessitating the investigation of some other solvent systems. OPV active material 

dissolved in alternate aromatic solvent ‘D’ gave better surface roughness. But as compared to solvent ‘B’

(21.8mm Hg vapor pressure at 20 oC), this solvent has very low volatility (0.18mm Hg vapor pressure at 

20 oC) and there was too much flow of material. If flow rate is increased or multi-pass is used instead of 

single pass to achieve the target thickness of 200nm, the material flowed towards the edge. A modified 

formulation with OPV active material dissolved in a mixture of the alternate aromatic solvent and solvent 

‘B’ may help achieve the desired thickness and surface roughness. The AFM data of surface roughness 

for OPV active material with different solvent mixtures are shown in Figure 31.

Figure 31: AFM profile of spray coated OPV active material for different solvent mixture (a) A:B=1:2, 

R(rms)= 45nm, (b) A:B:C=1:2:1, R(rms)= 87nm, (c) D:B =1:1, R(rms)= 4nm.

14.3.2 

Plextronics’ consultant, Prof. Sean Shaheen at University of Denver, worked on a model to identify the 

most robust module configuration against shorted cells. This includes simulating performance of 

modules having 54 identical cells, each having an active area of 1cm × 2cm, and organized in six parallel 

columns, each containing nine cells that are configured differently (see 

University of Denver

Figure 32). 

a. b. c.

a. b. c.
24

Figure 32: Module cells connected in different configurations

It was observed that with a full series configuration, there is a decrease in all device parameters with 9 

shorted cells in the module. Change in module configuration to a columnar design with parallel 

components does not lead to significant decrease in either of the device parameters, especially the current 

density. It was thus concluded that the consequences of shorted (weak) cells on module performance can 

be modestly mitigated by internal wiring configurations, but general improvements for any configuration 

can only come from identification and removal of the causes for the underperforming cells.
25

MILESTONE #15: Quarterly Report. 

15.1 

We reported on module efficiency and lifetime data – discussed in detail in Milestone #18 and #19, 

respectively).

Module Development

15.2 

During this quarter we added a Q-Sun testing unit for accelerated degradation studies on lab-cells and 

modules. The unit (See picture in 

Plextronics Testing Facility Update

Figure 33) which has 3 Xe-lamps built-in for large area uniform 

intensity is equipped with the Solar Eye Irradiance Control 

System. The solar eye automatically compensates for lamp 

aging and any other intensity variability. The light intensity 

can be controlled from 0.2 to 1.5 sun (300 to 3000 nm) by 

specifying the intensity of total UV. The relative humidity 

can be controlled from 10% to 85%, while varying the 

temperature from 25 oC to 100 oC. The large sample tray 

(17.75 in × 28.25 in) will allow several devices and modules 

to be tested simultaneously. We initiated test on devices 

with the help of this setup which will allow unique control 

over light, humidity and temperature. We are measuring the 

irradiance output within this test unit, humidity, as well as 

device surface temperatures to better understand the actual 

device testing conditions with this unit.

15.3 

On January 27th 2009, we hosted a ribboncutting ceremony to celebrate the opening 

of the company’s first manufacturing 

development line (D-Line) (see 

Plextronics’ OPV Manufacturing Development Line (D-Line)

Figure 

34). We intend to use this facility to print 

solar demonstration modules for the 

purpose of developing our printable solar 

inks using commercially relevant 

manufacturing techniques. The 

knowledge gained will be beneficial in 

pushing the performance of OPVs towards 

commercially relevant metrics, especially 

the goal of achieving grid-competitiveness 

by 2015. We have installed and have 

made operational several pieces of equipment and processes on the D-Line in areas such as: (1) Substrate 

cleaning and surface preparation, (2) Organic layer application, (3) Organic removal, (4) Cathode 

deposition, and (5) Encapsulation. 

Figure 33: Q-Sun Testing Unit

Figure 34: Plextronics’ state-of-the-art D-Line
26

MILESTONE #16: Deliver A Lab-Cell Sample.

KEY METRICS: Efficiency = 5.8% (NREL-certified).

Plextronics has demonstrated NREL-certified efficiencies of 5.98% utilizing proprietary Plexcore®

materials. The open-circuit voltage was measured at 0.8079V and a high fill factor of 71.67%. Figure 35

shows NREL-certified data for I-V (left) and the EQE spectrum (right) of the, respectively. At the time of 

the measurement, this was the highest NREL-certified OPV lab-cell. 

Figure 35 (left): I-V data of OPV device certified to 5.98% at NREL; (right): Normalized EQE spectrum 
27

MILESTONE #17: Lab-Cell Lifetime.

KEY METRICS: Lifetime = 5,776 hours to > 80% of its stabilized performance under 1 sun with 50% 

duty cycle. 

17.1 

Figure 36

Lifetime testing of OPV Lab-Cell

(left) shows the normalized efficiency performance of the champion lab-cell exposed to the Xelamp as a function of time. The decay rate (8.25%/kh) was extracted by removing the burn-in range and 

the T80 of 4848 hours was calculated based on our definition of OPV lifetime. Figure 36 (right) shows 

the corresponding J-V characteristics at the four different sampling times. 

Figure 36(left): Efficiency performance of champion lab-cell over 500 hours of light soaking; (right): J-V 

characteristics of the lab-cell

17.2

OPV lifetime is currently defined as the amount of time that an OPV cell, sub-module, or module 

diminishes to 80% (T80) of its initial ‘stabilized’ power output (or power conversion efficiency) and 

normalized by the illumination intensity (accounting for lamp variations and spectral mismatch). The 

illumination intensity is measured as ~1 Sun simulated by a Xenon arc lamp with (or converted to) 50% 

duty cycle.

Modification in OPV Lifetime Definition and Analysis

In this definition, a factor of two (2) was applied to data taken at 100% duty cycle, to simulate a day-night 

cycle of 50%. In actuality, the day-night cycle represents significantly less than 50% integrated 

illumination after accounting for total energy exposure that the lab cells receive. In this assumption, the 

intensity variation that occurs daily and seasonally in the real world is not properly accounted for. To 

account for these real world variations, we compared the solar radiation (KWh/m2

/day) that a flat-plate 

collector facing south at a fixed tilt receives in Phoenix, Arizona (AZ) and Pittsburgh, Pennsylvania (PA) 

monthly. According to a 30-year (1961-1990) average of monthly solar radiation at these two locations, 

the daily averaged solar radiation is about 6.5kWh/m2 and 4.2kWh/m2 in AZ and PA, respectively. 1

 This 

value is consistent with the annual climatological data (8000mJ/m2

/year at AZ) reported by Atlas (Atlas 

Material Testing Solution).2

 

Using a direct conversion from 1 sun (1000 W/m2

) to kWh/m2, the averaged incident intensity of our Xelamp was found to be 1.32kWh/m2

. Therefore, the daily irradiated power onto the devices under the Xelamp test setup is 1.32kWh/m2

×24h = 31.7kWh/m2. If we assume that the average solar radiation that a 

lab cell would receive at AZ (6.5kWh/m2

) and PA(4.2kWh/m2) would approximate the average solar 

radiation that a device would receive in various locations in the United States and factor in the total 

0 100 200 300 400 500 600

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Decay Rate = 8.25%/kh

T80 = 4848 hours

NE (a.u.)

Lifetime (hours)

 Best Cell

0.0 0.2 0.4 0.6 0.8 1.0

-10

-5

0

5

10

15

Jsc (mA/cm2

)

Voltage (V)

 0 h

 165 H

 242 h

 504 H
28

irradiance power that the OPV devices receive under a Xe-lamp at a 100% duty cycle (31.7kWh/m2), then

we derive a conversion factor of 5.93 (31.7 kWh/m2 /((6.5 kWh/m2 + 4.2 kWh/m2

)/2)).

By taking into account the conversion factor of 5.93 instead of 2, the T80 of the champion lab cell 

reported in Figure 36 is 14,362 hours (4848x3.0).

This re-calculation is based on the 

assumption that the performances of 

our devices are stable under no 

illumination (dark storage conditions). 

To verify that the OPV devices show 

no noticeable degradation during dark 

storage conditions, we compared the 

degradation of similar devices tested in 

the dark or placed under a Xe-lamp 

and irradiated at 1.32 suns. These 

results are summarized in Figure 37. 

The samples stored in dark showed no 

degradation over a time period of 

approximately 500 hours, and as a 

guide to the eye, a red dotted line is 

drawn at a normalized efficiency of 

one. In comparison, the devices 

irradiated under the Xe-lamp at 1.32 

suns decayed to almost 60% of their 

original efficiencies (including burnin). This suggests that the irradiance is 

one of the primary causes for degradation in OPV devices.

17.3 

Since the stability of the OPV devices has not been established or standardized, NREL requested the 

certification of lab cells before and after light soaking to better understand the degradation rates. In order 

to simulate the initial conditions of light stabilized devices, the following plan was implemented: 

NREL-certification of Lab-Cells

1. Age six (6) identical devices for 95 hours under the Xe-lamp to generate stabilized 

efficiencies.

2. Remove four (4) devices and place in the dark storage. 

3. Age remaining 2 devices for 260 more hours. (A total 360 hours of Xe-lamp exposure); one 

with a shadow mask and one without

4. Ship all devices to NREL for certification

Since we had previously observed that degradation starts from the edge in our current mapping studies, 

we implemented a mask to minimize the edge degradation effects. Of the six devices made, three were 

aged under the Xe-lamp with a shadow mask containing a 1mm × 2 mm window. Of the four devices 

removed for dark storage, two of the devices were aged under the Xe-lamp with a mask and two were 

aged without a mask. These samples, their testing history and a summary of their performances are 

shown in Table 2. The lab cells that were not removed for dark storage do not have a T=95h efficiency 

measurement (Devices 4326-2 and 4326-3). Lab-cells that were removed for dark storage do have the 

associated efficiency measurement at T=95h to derive the light stabilized initial performance. Their 

average performance has been noted (Devices 4326-4/6, 4326-5/7, 4326-8/9). The final efficiency 

recorded after 360 hours of light soaking under the Xe-lamp or dark storage is indicated for all lab-cells. 

All the lab-cells that were tested with the shadow mask are noted (Devices 4326-2,4,6). After 360 hours

light soaking, all devices were taken off the Xe-lamp and re-tested at Plextronics just prior to the 

shipment to NREL (labeled as 404 hours in Table 2) 

0 100 200 300 400 500

0.0

0.2

0.4

0.6

0.8

1.0

1.2

ηnormalized

Time, h

 PV2000 Xe lamp

 PV2000 dark, shelf life

Figure 37: A comparison of the effect of light 

irradiance versus dark storage conditions on the 

degradation of OPV devices.
29

The devices were tested at NREL and the results are included for comparison in Table 2 (the normalized 

E% of devices with different aging time is included below the actual measurements). From the shelf life 

devices, we can see the performance did not degrade (88% vs. 87%) during shipping from Plextronics to 

NREL. The NREL data of no Mask devices confirmed our previous conclusion that the device degraded 

about 10% (in green) during 265 hours post light soaking after being stabilized. The data from the 

devices with mask have 5% (in blue) degradation during 265 hours post light soaking probably due to the 

shift of masks position on the devices. 

These results corroborate our claim that the irradiance is one of the primary causes for degradation in 

OPV devices. The efficiency measurement at NREL was done with a shadow mask which the size of 

window is about 0.023 cm2

. But the NREL used the different area to calculate the efficiency, so the 

correct factor (ANREL/0.023) should be used to report the efficiency (shown in the last column of Table 2). 

Table 2 (top): The averaged E% of the devices with different aging time; (bottom): the normalized E% of 

devices with different aging time. Includes Plextronics’ and NREL measurements.

References

1.

:

2.

http://rredc.nrel.gov/solar/pubs/redbook/

http://www.atlasmts.com/en/services/natural_weathering_testing/natural_weathering_testing_sites/arizona/climatolo

gical_data/index.shtml

η (%)

η (%)
30

MILESTONE #18: Deliver A Module.

KEY METRICS: (Active area) Efficiency = 3.5% (NREL-certified).

OPV Module Efficiency

Plextronics has demonstrated NREL-certified OPV module efficiencies of 1.96% and 2.05% (total area) 

that translate in 4.06% and 4.24%

Figure 38

when re-calculated for Active Area (using Aperture Ratio of 0.4832). 

(a) and Figure 38 (b) shows NREL-certified data for Module 4100 and 4103, respectively, both 

having a 9S6P configuration (54 identical cells organized in 6 parallel columns of 9 cells each.

Figure 38: I-V OPV module (a) 4100 certified to 1.96% efficiency (4.06% active area efficiency) and (b) 4103 

certified to 2.05% efficiency (4.24% active area efficiency) at NREL
31

MILESTONE #19: Module Lifetime.

KEY METRICS: 5000 hours

The photograph in Figure 39 shows Plextronics’ 

OPV module and lab-cell lifetime testing set-up 

where currently nine OPV modules are on test 

under ~ 1 Sun illumination (Module 3541, under 

discussion, is identified). Module 3541, with an 

initial efficiency of 3.3%, was tested at regular 

intervals under open circuit conditions beneath a 1 

sun solar simulator, i.e. 1000 W/m2 adjusted with a 

National Renewable Energy Laboratory (NREL) 

certified KG-5 Si reference cell. The spectral 

mismatch was used to correct the current density. 

The module was made with the same materials, 

architecture and processes as used to meet 

Plextronics SAI subcontract milestone #18 (Module 

with 3.5% active area efficiency). Figure 40 (left) 

shows the normalized power output of the module after 1728 hours. Application of a linear fit to the data 

gives a decay rate of 3.77% per 1000 hours, which corresponds to a lifetime of 5298 hours

Figure 40

under the old 

lifetime definition. Based on the modification of the lifetime definition we proposed in milestone #17, 

the actual lifetime of the module is expected to be greater than 10,000 hours. (right) shows the 

J-V characteristics of the module under illumination at periodic intervals. 

Figure 40 (left): Normalized power output of Module 3541 tested over periodic intervals under AM1.5G solar 

simulator. The decay rate of 3.77%/1000 hours corresponds to lifetime of 5298 hours under old definition 

and over 10,000 hours as per the modified definition; (right): AM1.5G solar simulation J-V characteristics of 

the Module 3541 under ~ 1Sun Xe lamp.

0 2 4 6 8 10

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

J

sc (mA/cm2

)

Voltage (V, 9s6p)

 0 H

 216 H

 624 H

 1032 H

 1248 H

 1344 H

 1728 H

0 400 800 1200 1600

0.0

0.2

0.4

0.6

0.8

1.0

NP (a.u.)

Life Time (hours)

 3541

Slope = -7.55E-5

Module 3541

Figure 39: Plextronics’ lifetime setup. Module 

3541 is marked.
32

MILESTONE # 20: Deliver Monolithic Stripe Design Module.

KEY METRICS: Active area (>95 cm2) Efficiency >2%; Total area Efficiency >0.82% (NRELcertified). 

20.1 

20.1.1 

Plextronics Module Designs

OPV modules are fabricated on a 150 mm × 150 mm ITO coated glass substrate, which has been fortified 

with a metal frame for improved collection of holes. For the prior deliverables, the modules were

designed with a specific configuration of cells to allow maximum utilization of area, while delivering the 

optimum operating voltage for a particular application. 

9s6p Design

Figure 41 shows the design of a Plextronics 

module which consists of 54 identical cells, each having an active area of 1cm × 2cm. The cells are 

organized in six parallel columns, each containing nine cells that are connected in series by internal 

wiring. The columns are electrically isolated, which provides an opportunity to independently measure 

each column’s performance. External wiring is used to configure the module in several ways. The cells 

are connected in 9s6p configuration (6 columns connected in parallel). This design was adopted for 

development purpose. 

Figure 41: Design of Plextronics OPV Module, with 54 identical cells connected in 6 parallel columns of 9 

cells each (right).

20.1.2 

We have redesigned the OPV module topology in order to improve its aperture ratio and at the same time 

to improve its manufacturability. The Stripe Module v.1.1 consists of 10 stripes, each having active area 

of 9.9 cm2 (total active area of 99 cm2

). The stripes are internally connected in series (into one wide 

column) as shown in 

Stripe Design

Figure 42. The Aperture Ratio has been improved from 0.46 for previous design to 

0.623 for the stripe design. The number of stripes has been design to produce a module with Vpp = 6.0 

V.

Metal contact

Seal between substrate

and cavity glass

OPV cell
33

Figure 42: Stripe organization on new Stripe Module v.1.1 (ITO pattern)

20.2 

Plextronics has demonstrated NREL-certified OPV 

Module Efficiency

module efficiency of 1.30% (total area) that translates 

to 2.09% when re-calculated for Active Area (using Aperture Ratio of 0.64). Figure 43 shows the NRELcertified data for Module 4202. 

Figure 43: I-V data of OPV module NREL-certified to 2.09% active area efficiency
34

MILESTONE # 21: Monolithic Stripe Design Module.

KEY METRICS: Module with 1000 hours light-soaking (100% duty cycle) near 25 °C, >1.6% final 

active area efficiency (0.66% total area) (NREL-certified). 

The lifetime and stability of a 150 mm × 150 mm Plexcore® PV2000 ink system on a monolithic (R&D) 

‘stripe’ module under 1000 hours of continuous light soaking conditions was reported. We found that 

once the encapsulation seal had been engineered to ensure good adhesion between the cap glass and glass 

substrates, these modules demonstrate good stability - degrading only 20% of their initial performance. 

Figure 44 shows the NREL-certification of the ‘stripe’ design module after 1000 hours of light soaking 

under 1 sun Xe-lamp. The module was measured to exhibit 2.71% active area efficiency (1.71% total 

area efficiency). The aperture ratio is 0.63. 

Figure 44: NREL-certification of ‘stripe’ design module after 1000 hours of light soaking
35

MILESTONE #22: OPV Module Outdoor Lifetime. 

KEY METRICS: Data comparison analysis of at least 6 modules for outdoor testing (at least 1000 hours 

data collection, real time) at Golden, CO and Pittsburgh, PA.

We have setup two identical outdoor testing stations at Golden, CO and Pittsburgh, PA at 5/22/2009 and 

6/6/2009, respectively (see Figure 45). 9 OPV modules have been working very well and their 

performance is being monitored on each station. So far all modules have experienced > 1500 hours 

outdoor exposure from both locations. 

Figure 45: Two identical testing stations at Golden, CO and Pittsburgh, PA

The modules are tested in 9s6p mode once every 10 seconds. The data include the time, current, voltage, 

power, temperature, and pyranometer signals. The data are used in the calculations below. 

1. Data is chosen at 1 sun illumination (990~1010 W/m2

) determined by a calibrated pyranometer. 

2. From this illumination, we calculate the efficiency for each module as η = P/B, where P = power 

output from module in W/m2 and B = illumination level in 1000 W/m2

.

3. Each day, we calculate the average η value as the simple mean of all the values calculated in #2 at 

a constant illumination of 1 sun (1000±10W/m2

).

The normalized data are plotted as η vs. time. Results from Golden, CO and Pittsburgh, PA were shown in 

Figure 46. Green and purple lines indicate devices made with our Plexcore® PV1000 and Plexcore®

PV2000 inks, respectively. We can see there is an outlier module for each of station which may represent 

a poor performing module on each plot. 

Figure 46: Outdoor output of OPV Modules at Golden, CO (left) and Pittsburgh, PA (right)

The modules at NREL are observed to degrade faster than the representative set at Plextronics. Our 

indoor lifetime experiments have implicated the irradiation is a primary degradation factor. The 

difference in temperature between the two sites may have some contribution to the degradation. 

Averaged irradiance difference between NREL and Plextronics is 5.66 kWh/m2

/day vs. 4.19 kWh/m2/day 

(determined by Pyranometer) during testing period. The difference in the degradation rate of the best 3 

modules from NREL and Plextronics is 10.8%/khrs vs. 6.21%/khrs. The analysis is not statistically 

studied, however it directionally explores the root of degradation. 
36

MILESTONE #23: Deliver 9s6p Module fabricated on D-Line.

KEY METRICS: Active area (>95 cm2) Efficiency >1.5%; Total area Efficiency >0.7% (NRELcertified). 

23.1 

The main purpose of D-line is to demonstrate Plextronics’ potential customers that our solution 

processable inks will support the migration from R&D into manufacturing environment. For that reason 

the application technique for depositing of active layer (AL) was changed from spinning to slot-die 

coating. This technique was chosen because of very good field test results, very good utilization of the 

ink (minimum waste) and for compatibility with flexible substrates processing. The change of application 

technique induced additional processing changes that were necessitated by practicality of each particular 

operation. The part of process in which the changes occurred is shown below (HTL – Hole transport 

layer):

Module Fabrication on the D-Line

R&D

HTL spun on in air HTL spun on in air

D-Line

HTL annealed in inert atmosphere HTL annealed in air

AL spun on in inert atmosphere AL coated by slot die in air

No exposure to vacuum Exposed to vacuum (ante chamber)

AL annealed in inert atmosphere AL annealed in inert atmosphere

23.2 

Plextronics has demonstrated NREL-certified OPV module 

Module Efficiency

efficiency of 1.43% (total area) that translates 

to 3.08% when re-calculated for Active Area (using Aperture Ratio of 0.464). Figure 47 shows the 

NREL-certified data for Module 4/21-3. This module was fabricated on our manufacturing development 

line (D-Line) with the active layer (AL) deposited using slot-die coating. 

Figure 47: I-V data of D-line OPV module certified to 2.09% active area efficiency (1.3% active 

area efficiency) at NREL
37

MILESTONE #24: Effects of light soaking on modules.

KEY METRICS: Module with 500 hours light-soaking (100% duty cycle) near 25 °C, initial efficiency 

>2.5%, final efficiency >2% (1.2% and 0.93% total area efficiency) (NREL-certified).

Module #4612 (with active area=108 cm2

) was evaluated indoors for 510 hrs under Xe-lamp (100% duty 

cycle) after light stabilizing the modules under Xe-lamp for 168hrs. The module was certified by NREL 

after the initial stabilization process and subsequent 500hr light soaking. The initial light stabilized active 

area efficiency for module #4612 was 4.49% (certified full area efficiency = 2.16%). The active area 

efficiency after an additional 510 hrs of light soaking was 4.33% (certified full area efficiency = 2.08%)

Figure 48

. 

The efficiency has degraded to ~3.6% of its initial efficiency, thus satisfying the deliverable requirement 

of <80% degradation of initial light stabilized efficiency. shows the NREL-certified data 

before (left) and after light soaking (right). 

Figure 48: NREL certification of module #4612 before (left) and after 510 hrs of light stabilization under Xelamp at 1 sun (right)
38

MILESTONE #25: Stability of Modules at 85oC/85% Relative Humidity (RH) Conditions. 

KEY METRICS: Module with 500 hours light-soaking near 85 °C/85% RH, Stability after 200 hours to 

be >50% of original, test to be conducted on module with >2% active area efficiency (0.93% total area 

efficiency). 

The testing was carried out in a Q-Sun chamber that utilizes a Xe-arc lamp with a Daylight-Q filter, 

having a near spectral response match to the Xe-lamps utilized for ambient testing and reporting the 

module stability other PV-Incubator deliverables. A maximum achievable power output of 79 W/m2 was 

maintained over the total UV region (295-320nm), which corresponds to a power irradiance of 1220 

W/m2 over the spectral region. This is 1.6 times the amount of irradiance that a module would see under 

ambient, Xe-lamp. 

In Figure 49, the performance of a Plexcore® PV2000 ink system module under light soaking at 

“85oC/85%RH” testing conditions, 100% duty cycle, is presented. The initial, post fabrication device 

performance (T0) was 2.72% active area power conversion efficiency (PCE). Directly after measurement, 

the module was loaded into the Q-Sun chamber. We found that it took 336 hours to reach 50% of initial 

post fabrication device performance (T50), exceeding the deliverable metrics for this milestone. At T50, 

the active area PCE was measured to be 1.36%. We observed that the module continued to degrade for 

up to 528 hours before undergoing catastrophic failure.

Figure 49: Performance of module under light soaking at “85oC/85%RH” testing conditions. It took 336 

hours to reach 50% of initial post fabrication device performance (T50). The JV plots at T0 and T50 are 

shown in the inset.

The ability to report the stability of modules under standardized, accelerated testing conditions paves the 

way to assessing the composite effect of materials, device configuration and encapsulants that comprise 

OPV thin film technology. The ability of OPVs to meet and exceed the rigorous testing methods set out 

by The International Electrotechnical Commission (IEC) will be an important milestone towards 

commercialization of this technology.
39

MILESTONE #26

A draft of the final report was submitted to the technical monitor. 

: Draft Final Report. 
40

Plextronics has successfully met on schedule, or in many cases ahead of schedule, all of the milestones (to 

date) set for the PV-Incubator program. 

Conclusions and Outlook

Table 1 shows the metrics for efficiency and lifetime of lab-cells 

and modules as per the contract, and the actual targets that we achieved. It can be seen that we exceeded 

expectations for almost all of the milestones. 

Table 3: Summary of efficiency and lifetime metrics (contract vs. actual)

The program has allowed us to expand our 

capabilities of organic materials synthesis, ink 

formulation, device design and fabrication, and 

device testing. Furthermore, during this program, 

we established and made operational our largearea OPV manufacturing development line (DLine). Through these efforts, we are developing 

fabrication techniques to drive down 

manufactured costs of commercial design 

modules via high throughput processes. Figure 50

outlines our approach and our pathway towards 

achieving the SETP goals. We also look forward 

to a continuing relationship with NREL to 

establish standards for OPV technology. 

Milestone # Contract Actual

1 5.1% (NERL-cert) 5.09%

2 5.4% (Internal) 5.51%

5 5.4% (NREL-cert) 5.42%

16 5.8% (NREL-cert) 5.98%

1 0.8% (Internal) 1.07%

6 1% (Internal) 1.07%

12 1.5% (NREL-cert) 2.30%

18 3.5% (NREL-cert) 4.24%

20 2% (NREL-cert) - new design 2.09%

23 1.5% (NREL-cert) - D-Line 3.08%

1 700 hours to T80 750 hours to T90

10 3,723 hours to T80 5,600 hours to T80 (extrapolated)

17 5,776 hours to T80 > 14,000 hours to T80 (extrapolated)

12 2,000 hours to T80 > 4,000 hours to T80 (extrapolated)

19 5,000 hours > 10,000 hours to T80 (extrapolated)

21 1.6% efficiency (NREL-cert) 

after 1000 hours light soak - new 

design

2.71%

24 Initial efficiency = 2.5% (NRELcert); 500 hours light soak; Final 

efficiency = 2% (NREL-cert)

Initial efficiency = 4.49%; Final 

efficiency = 4.33%

25 Initial efficiency = 2%; 500 hours 

light soak at 85 °C/85RH; 

Efficiency at 50% of original 

after 200 hours

Initial efficiency = 2.72%; T50 at 336 

hours

Lab-Cell Efficiency

Module Efficiency 

(active area)

Lab-Cell Lifetime

Module Lifetime

Figure 50: Plextronics’ approach: (1) 

Technology improvement via higher efficiency 

and longer lifetime; (2) Cost reduction via 

effective translation to commercial modules 

and high-throughput processes

Cost

TECHNOLOGY IMPROVEMENT

COST REDUCTION

MATERIALS

EFFICIENCY

DEVICE

LIFETIME

TRANSLATION

TO MODULES

PROCESS

DEVELOPMENT
F1146-E(10/2008)

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PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION.

1. REPORT DATE (DD-MM-YYYY)

December 2009

2. REPORT TYPE

Subcontractor Report

3. DATES COVERED (From - To)

09/28/2007-10/27/2008

4. TITLE AND SUBTITLE

Economic On-Grid Solar Energy via Organic Thin Film Technology: 

28 September 2007 - 27 October 2008

5a. CONTRACT NUMBER

DE-AC36-08-GO28308

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

D. Laird, J. Bernkopf, S. Jia, J. Krieg, S. Li, C. McGuiness, 

J. Rossier, M. Storch, R. Tipnis, R. Tuttle, B. Woodworth, and 

S. Williams

5d. PROJECT NUMBER

NREL/SR-520-47289

5e. TASK NUMBER

PVB92110

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

Plextronics, Inc.

2180 William Pitt Way

Pittsburgh, Pennsylvania 15238

8. PERFORMING ORGANIZATION

REPORT NUMBER

NAT-7-77015-06

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Renewable Energy Laboratory

1617 Cole Blvd.

Golden, CO 80401-3393

10. SPONSOR/MONITOR'S ACRONYM(S)

NREL

11. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NREL/SR-520-47289

12. DISTRIBUTION AVAILABILITY STATEMENT

National Technical Information Service

U.S. Department of Commerce

5285 Port Royal Road

Springfield, VA 22161

13. SUPPLEMENTARY NOTES

NREL Technical Monitor: Bolko von Roedern

14. ABSTRACT (Maximum 200 Words)

The goal of Plextronics, Inc.'s Solar America Initiative PV Incubator contract was to take its organic photovoltaic 

(OPV) technology from laboratory-scale and demonstrate a pathway to 3-W manufacturing capacity (~2010) and 7

cents/kWh levelized cost of energy by 2015. The work supports the Solar Energy Technology Program charter as 

follows: (1) Driving commercialization of novel, low-cost thin-film PV technology by developing commercial highperformance OPV inks to enable module production; (2) Systematically, quantitatively evaluating technological 

options on the pathway to achieving grid parity with conventional power sources; (3) Demonstrating an OPV module 

development line and using it as a pathway to establishing a high-volume manufacturing facility that will eventually 

contribute to U.S. installed domestic capacity for PV systems. Plextronics used a three-pronged approach to meet 

the Incubator goals: (1) Drive device efficiency via materials development; (2) Improve stability and lifetime via device 

design and process development; (3) Translate lab-scale performance to large-area modules by establishing a pilot 

manufacturing-development line to evaluate manufacturing-worthy processes.

15. SUBJECT TERMS

PV; on-grid; solar energy; organic photovoltaics; thin film; manufacturing; capacity; large-area modules

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