Basic Study of Surface Modification forFilm Dye Sensitized Solar Cells using Microplasma
S. Kaneta, M. Blajan, T. Onodera, A. Konno and K. Shimizu
Graduate School of Engineering, Shizuoka University
3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka 432-8561, Japan

1. Introduction
The film dye sensitized solar cells (Film DSSCs) are well known as cost-effective technology and high designability devises. Althoughmany advances have been made in film DSSCs fabrication of late years, their conversion efficiency remains still lower than the glass
substrate DSSCs. This poster introduces improvement of conversion efficiency of film DSSCs using atmospheric pressure microplasma
as a low damage process.

2. Experimental setup and Target
Target: Binder free Titanium oxide
Calcining temperature : 120 ﾟC
Calcining time : 15 min
Dye : N719 dye
Immersion time : 22 hProcess gas : Oxygen and Argon
Irradiation distance: 1.0 mm
Gas flow rate : 5.0 L/min.
Chamber volume : 1.0 L
Treatment time : 15 min
The experimental set up for surface modification

The advantages of Microplasma process

・Remote and damage less processApplied voltage (O2) : 1.6 kVApplied voltage (Ar) : 0.6 kVPower consumption (O2) : 3.8 W

The construction of film dye sensitized solar cells

Disadvantage
・Low conversion efficiency

Power consumption (Ar) : 2.6 W

・No need for vacuum chamber

3. Result and discussion
I-V characteristics

Advantages
・Low cost material
・Simplified manufacturing
・High designability

Dye adsorption amount

I-V characteristics of oxygen plasma sample

I-V characteristics of argon plasma sample

Control
Current density : 3.56 mA/cm2Conversion efficiency : 1.37%
Oxygen microplasma
Current density : 4.80 mA/cm2Conversion efficiency : 1.99%

Control
Current density : 3.81 mA/cm2
Conversion efficiency : 1.53%
Argon microplasma
Current density : 4.79 mA/cm2
Conversion efficiency : 1.87%

XPS analysis

Dye adsorption amount of Titanium oxide surface

Dye adsorption amount was increased after both microplasma treatment.
Dye adsorption consist of the ester bonds between hydroxide on
Titanium surface and carboxyl group. After both plasma treatments,hydroxide was increased on Titanium oxide surface. Titanium oxidesurface tend to make ester bonds. This change contributed to theincrease of dye adsorption amount and current density.

SEM analysis

O1s peaks of control sample

O1s peaks of oxygen microplasma sample

Atomic concentration of Titanium oxide surface

Ti-OH peak was increased after both
microplasma treatment processes.
FE-SEM images of Titanium oxide surface

Introduction of hydrophilic groups
on Titanium oxide surface
wasconfirmed.

Magnification : 30000x
Treatment time : 15 min.

Significant changes between control sample
and plasma treated sample were not obtained.

4.Conclusions
1. Conversion efficiency of plasma treated sample was increased with about 20 - 40% compare with control sample.
2. According to XPS analysis, OH bond was increased after both plasma treatments. The improvement of hydrophilicity on titanium oxide surface
contributed to the increase of dye adsorption amount.
3. Significant changes on titanium oxide surface were not observed using SEM.

Shimizu Laboratory