鉑之濺鍍沉積厚度與分子修飾陽極對染料敏化太陽能電池效能之影響

Impacts of sputter-deposited platinum thickness and molecular modification of anodes on performance of dye-sensitized solar cells

林俊竹(Chun-Chu Lin)

指導教授 ： 卓君珮 ； 鄭淑華

國立暨南國際大學/科技學院/光電科技碩士學位學程/碩士(2014年)

摘要

本研究分成兩部分，第一部分是通過調整鉑電極的濺鍍時間來控制鉑的沉積厚度和表面粗糙度，較大的表面粗糙度對催化活性較有利。當濺鍍時間為40 s時，DSSC會有最大的短路電流密度和最高的光電轉換效率6.81 %，而當濺鍍時間增加，使得鉑厚度也增加時，短路電流密度和光電轉換效率都會減小，因此沉積較厚的鉑對DSSC有不利的影響，本研究證實濺鍍時間為40 s時可形成最佳的鉑沉積，厚度約為30 A。
第二部分是利用有機分子在二氧化鈦表面形成自組裝單分子層，對光電極進行表面改質，主要是為了降低電荷傳輸的能障。本研究共選用七種有機分子，其中AEPA自組裝單分子層對電極的表面修飾使得DSSC有最大的短路電流密度和最高的光電轉換效率6.67 %。此外，本研究以電化學分析證明經AEPA修飾後，光電極之氧化還原電流會上升，表示電荷傳輸較快及較容易轉移，可提升光電流和光電轉換效率。我們也發現分子的挑選不能只看偶極矩，末端基種類和分子長度都可能影響二氧化鈦電極之表面和界面特性，進而影響DSSC之各光伏參數和元件效能。

關鍵字

鉑對電極 ； 濺鍍 ； 自組裝單分子層 ； 分子修飾 ； 染料敏化太陽能電池

並列摘要

This study can be divided into two parts. The first part is control over Pt thickness and surface roughness of platinized counter electrode by adjusting sputtering time. A larger surface roughness would be more beneficial to the catalytic activity of Pt. The DSSC using sputtering time of 40 s exhibited the largest short-circuit photocurrent density and highest energy conversion efficiency of 6.81%. Both short-circuit photocurrent density and energy conversion efficiency were reduced as longer sputtering time was employed. So increased Pt thickness was unfavorable for DSSC performance. The sputtering time of 40 s has been regarded as the optimum condition to form the most appropriate Pt thickness of around 30 A.
The second part is molecular modification on TiO2 photoanode by self-assembled monolayers to lower the energy barrier of charge transfer. Seven organic molecules were selected to form self-assembled monolayers in this part. The DSSC modified by AEPA exhibited the largest short-circuit photocurrent density and highest efficiency of 6.67%. Moreover, it has been proved by electrochemical methods that the redox current increased when photoanode was modified by AEPA. Easier and faster charge transport were then resulted, and increased photocurrent and higher efficiency were achieved. The type of terminal group and molecular length also affected surface and interfacial properties of TiO2 electrode, and the photovoltaic parameters and device performance of DSSC were thereby influenced.

並列關鍵字

Pt counter electrode ； sputtering ； self-assembled monolayer (SAM) ； molecular modification ； dye-sensitized solar cell (DSSC)

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