PVP-capped Pt Nano-Clusters as Catalyst for Counter Electrode of Dye Sensitized Solar Cell and Grid-type DSSC Module

高分子包覆奈米鉑簇運用於染料敏化太陽能電池與模組之陰極研究

藍若琳(Jo-Lin Lan)

指導教授 ： 萬其超

國立清華大學/工學院/化學工程學系/博士(2011年)

https://doi.org/10.6843/NTHU.2011.00078

摘要

We have developed (Poly-N-vinyl-2-pyrrolidone) PVP-capped Pt nano-clusters on transparent conductive oxide (TCO) glasses via a simple “2-step dip coating process” as counter electrode for DSSC. This new counter electrode was examined by transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), thermal gravimetric analysis (TGA), and current-voltage curve (I-V curve). The TEM results reveal that PVP-capped Pt nano-clusters’ size is about 3nm, and the amount of Pt deposited on ITO glass is about 5 μg/cm2. TGA results show that the optimum annealing condition for PVP-capped Pt nanoclusters counter electrode (PVP-Pt CE) is around 270oC 15mins, and charge transfer resistance (RCT) was found below 1 ohm-cm2 and the power conversion efficiency with this counter electrode could exceed 9%.
Besides being deposited on TCO glass, PVP-capped Pt nano-clusters can also be coated on flexible carbon fiber paper via the same “2-step dip coating process”. This kind of counter electrode has not only acceptable catalytic activity, but low sheet resistance, cheap cost and flexibility. In addition, the production can employ by continuous spinning technology under ambient conditions in the future. Hence mass production will be much easier and less expensive.
Furthermore, the durability of PVP-Pt CE on TCO glass for dye-sensitized solar cell (DSSC) has been extensively evaluated including electrochemical reaction durability, thermal stress durability and light soaking durability. It is revealed that PVP-Pt CE exhibits both electrochemical and thermal durability by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) test. As for the device thermal durability, both low-volatile and non-volatile electrolyte systems were tested and the results show that the relative efficiency can remain above 85 % after accelerated thermal test at 85oC for 1000 hours, and 110% after 60oC for 1000 hours. For the light soaking test under 60oC after 1000 hours, the relative efficiency can still be maintained at 94%.
We also applied PVP- Pt CE to large scale grid-type DSSC module, and studied the correlation between the resistive loss and the output power by altering the Ag grid pattern. Further indoor application of grid-type DSSC module was integrated with a fluorescent lamp stand. In order to improve the DSSC performance at various incident light conditions, the relationship between the power conversion efficiency and the electrochemical impedance spectrum was explored, and we found that the iodine concentration in the electrolyte was key factor affecting the DSSC performance. Therefore, by optimizing the composition of electrolyte for low incident light condition, we can improve the output power by nearly 15% for each DSSC module.

關鍵字

染料敏化太陽能電池及模組 ； 奈米鉑對電極

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