15 Feb 2005

Dr. Harin S. Ullal

MS 3212

National Center for Photovoltaics

National Renewable Energy Laboratory

1617 Cole Blvd

Golden, CO 80401

Subject: RDJ-2-30630-20 (Research Leading to High Throughput
Manufacturing of Thin-Film CdTe PV Modules); Q9 Quarterly Report.
Deliverable D.3.1

Principal Investigator: Dr. Rick Powell

Dear Dr. Ullal,

During the ninth quarter of the subject subcontract the following work
was performed:

# General

We completed the move from Technology Center facilities at Eckel
Junction Road. All development personnel and equipment is now located at
the Cedar Park facility. Nearly all of the equipment has been installed
and is operational. We expect the move to improve the effectiveness of
the Technology Development Team.

# Vapor Transport Deposition (VTD)

## Reactor Development

During this reporting period, work continued on the development of VTD-2
type distributors. We have been concentrating on the G3 design for CdTe.
Another very successful pre-production trial was conducted with about
200 plates coated. This test confirmed the previous experiment with
respect to uniformity and material utilization. About half of these
plates have been converted into modules with efficiencies slightly
better than standard production modules. The microstructure of the films
deposited with the G3 distributor is different and alteration in
downstream processing is required to produce good efficiency modules.
Additional accelerated life testing is underway including field
deployment. Additional optimization is also being conducted at the cell
level (see below).

## Reactor Modeling

During this quarter theoretical reactor modeling work (at CSM)
concentrated on models of vapor transport between the distributor and
the glass. Development of calculation strategies and boundary conditions
progressed. It appears that some full 3-dimensional fluid calculations
will be necessary to guide boundary condition approximations for the
faster simplified calculations that will be useful in digital
optimization experiments.

# Advanced Front Contact 

Earlier this year we chose to concentrate on depositing the front
contact buffer layers on full size plates with production capable
processes so that full modules could be fabricated. We wanted to rapidly
transition this technology to production if its benefits at the module
level could be demonstrated. We were successful in achieving target film
properties for the zinc stannate buffer layers. During this quarter we
completed a fairly comprehensive second round of downstream process
optimization on full size modules that employ zinc stannate buffer
layers and thin CdS. To date, we have not been able to demonstrate that
use of a buffer layer allows thinner CdS layers for increased
photocurrent while maintaining high Voc as expected. While we are
contemplating other experimental tests, the zinc stannate buffer layer
does not appear to deliver the expected benefits at the module scale.
Consequently we plan to investigate other buffer layer types.

# Stability Issues 

## Accelerated Life Testing

The more rapid ALT test developed over the last several years continues
to show good correlation to the older light soak protocol for most
processing variations tested. This procedure has been applied to
unencapsulated modules and module sections as well as completed modules.
Additional equipment is being constructed to increase the number of
modules that can be tested with the rapid ALT procedure. We expect that
over the next 2 quarters, that this new procedure will become the most
widely used test for assessing module stability.

## Stress Induced Changes/Chloride Treatment/Back Contact Issues

Activities in this area focused on optimization of processing of small
area devices made with films deposited with the new G3 VTD distributor.
The current effort is concentrating on what are believed to be the best
G3 deposition conditions only. All G3 films appear to have higher
density and other microstructure differences compared to standard
material. The optimum CdCl~2~ and other downstream processing conditions
are different for these films. The best processing conditions found so
far for cells made on G3 material result in cells with slightly lower
initial efficiency compared to standard material, but improved light
soak stability. A detailed study of IV, QE, and CV measurements during
light soak testing is ongoing.

**Third Level Metrics**

A large partial factorial experiment involving significant process
variations and about 150 full sized modules was conducted to generate a
set of samples to explore a variety of in-process measurements. Samples
at partially completed stages were set aside and cut for some
measurements while sister plates were continued through the entire
process. A set of finished modules representative of the partial
factorial experiment are slated to be field deployed.

# Environmental, Health, and Safety

During this quarter we continued to work with copper smelters to find
ways to supply recycle scrap modules.

We also spent time in preparation for our first audit to achieve ISO
14001 certification of our environmental program. This audit was
conducted during the first week of January and we have been notified
that we will receive ISO 14001 certification.

Best Regards,

RC Powell

Principal Investigator

First Solar, LLC

28101 Cedar Park Blvd.

Perrysburg, OH 43551

Tel: (419) 662-7549

Fax: (419) 662-8525

rcpowell@firstsolar.com

cc: Ms. Carolyn Lopez

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