臺灣博碩士論文加值系統

有機固態太陽能電池近幾年已逐漸受到各界重視，主要原因是其效率雖不如矽晶太陽能電池，但還可達到5~6 %，且其製作成本相較於矽晶太陽能電池來得便宜且簡易，對於可撓性及輕量化方面亦是矽晶太陽能電池所無法比擬的，故科學家才會持續不斷地探討其工作機制與元件效能。雖然有機固態太陽能電池效率表現尚無法運用至耗電量較大之設備上，卻已可操作於小型風扇或電子計算機等耗電量低之電器上。本研究主要目的乃探討電子施受體比例與電子傳輸層、電洞傳輸層對於單層異質接面太陽能電池效能的影響，並提出氧化聚合電洞傳輸層製備方法，以改進元件在含有水氣的環境下元件老化的問題。

在電子施受體比例之研究方面，本研究嘗試改變不同比例之poly(3-hexylthiophene) ( P3HT ) 與C60衍生物[6,6]-phenyl-C61-butyric acid methyl ester ( PCBM ) 比例並製作太陽能電池元件，觀察元件效率與短路電流隨著施受體比例改變之趨勢，發現當固定電子施體濃度，增加受體濃度時，元件效率與短路電流會隨之增加，且在施受體重量比例為1：0.8時達到最佳值。然而，如再增加受體濃度反而導致電池元件與短路電流同時下降。本研究利用原子力顯微鏡來觀察電子施受體之比例對於薄膜表面形態之影響，發現當固定施體濃度，逐漸增加受體比例，薄膜中相分離之現象會漸趨明顯，至施受體重量比超過1：0.8以後，則會發生縱向相分離。因此，此現象再配合元件性能可得知，應選擇適當的施受體重量比 ( 本研究之最佳比例為1：0.8 )，才能避免過度的相分離發生，以降低電子再結合機率，使短路電流與元件效率能同時維持在最高點。

在電洞傳輸層方面，本研究將比較PEDOT:PSS加入DMSO成膜後對元件效率的影響，並經由交流阻抗分析方法觀察加入不同量的DMSO所形成的PEDOT:PSS膜在元件中對於電荷載子移動所造成的阻力變化。結果發現，當加入DMSO於PEDOT:PSS薄膜後，由交流阻抗分析中發現阻抗有降低之趨勢，然而元件整體效率卻不如原始沒有加DMSO的表現。有關原因目前正在調查文獻並設法透過其它分析方式研究中。在電子傳輸層方面，本研究比較元件是否含有LiF緩衝層 ( buffer layer ) 對於元件效率的影響，發現加入LiF電子傳輸層可以增加電池的短路電流以及Fill Factor，有效增加光電轉換效率。

本研究在未使用手套箱與無塵室的環境下，製作之太陽能電池元件效率在100 mW/cm2之光強度照射下可達2.68 % ( 反應面積0.25 cm2 )，而D. L. Carroll團隊及A. J. Heeger團隊在2005年以類似系統 ( P3HT與PCBM ) 於手套箱、無塵室中分別做出在80 mW/cm2光照下的4.9 % ( 反應面積0.19 cm2 ) 及5.1 % ( 反應面積0.148 cm2 )。由此元件效率數據顯示，吾人所製作之元件的性能雖不及上述兩研究團隊，不過元件製作技術目前已驅成熟，相信未來能在手套箱環境下進行元件製作，可以更佳提升元件效率，進而迎頭趕上國外研究團隊。

Solid type polymer solar cells has been hotly studied in this decade, although the efficiency is still lower than 5~6 %, its low fabrication cost and easy process make it attractive to researchers, and its flexibility is another outstanding property. It’s power conversion efficiency is low but already enough for some low power devices, such as small fans or calculators. This study is mainly discussing the effect of donor/acceptor ratio, electron transfer layer and hole transfer layer on the performances of bulk heterojunction solar cells, and suggests a process of oxidation polymerization of hole transfer layer in order to prevent the degradation of cell in the environment containing water molecules.

In the research of donor/acceptor ratio, we tried to fabricate solar cell devices with different ratio of donor and acceptor and observe the trend of cell efficiency and short circuit current change with donor/acceptor ratio, and we found that when we fix the concentration of electron donor, and increase the concentration of acceptor, the cell efficiency and short circuit current increases, at the point of donor/acceptor = 1/0.8 reaches the optimum. And if we keep on increasing the concentration of acceptor, the cell performance and short circuit current decreases gradually. In this research, we use atomic force microscope ( AFM ) to observe the morphology of thin film, and found that when acceptor increases, the phase separation in the thin film will increase, when the acceptor concentration is higher than donor/acceptor = 1/0.8, vertical phase separation will occur, and the possibility of recombination will be increased.

This research also tried to increase the conductivity of hole transfer layer by adding DMSO into PEDOS:PSS solution. We found that the conductivity will not be improved by adding DMSO into PEDOT:PSS solution, because the mixed solution cannot provide a perfect thin film. We also compare the cell performances with and without LiF electron transfer layer and found that adding LiF layer can increase the cell efficiency by increasing short circuit current and fill factor.

In this research, we did not fabricate our solar cell devices in the glove box or in the clean room, and we get 2.68 % power conversion efficiency under 100 mW/cm2. Our cell performances are still low, but higher cell conversion efficiency is expectable when the solar cell devices are fabricated in the glove box.

中文摘要 I
英文摘要 III
致謝 V
目錄 VII
表目錄 X
圖目錄 XII


第一章 緒論 1
1-1 前言 1
1-2 太陽能電池技術簡介 2
1-2-1 半導體簡介 4
1-2-2 太陽能電池類型 7
1-2-2-a無機太陽能電池 7
1-2-2-b染料敏化太陽能電池 9
1-2-2-c層疊式太陽能電池(Tandem cell) 10
1-2-2-d有機電子施受體單/雙層異質接面太陽能電池 10
1-2-3 高分子單層異質接面太陽能電池 17
1-3 交流阻抗分析原理 23

第二章 文獻回顧與研究目的 31
2-1 有機半導體太陽能電池 31
2-1-1 單層結構太陽能電池 31
2-1-2 電子施/受體雙層結構太陽能電池 31
2-1-3 電子施/受體單層異質接面太陽能電池 31
2-2 太陽能電池特徵曲線與電池輸出常數 41
2-2-1 短路電流(Short Circuit Current, ISC) 43
2-2-2 開環電壓(Open Circuit Voltage, VOC) 44
2-2-3 填充因子(Fill Factor, FF) 45
2-3 研究動機與架構 46

第三章 實驗設備與方法 48
3-1 儀器設備 48
3-2 實驗藥品 49
3-3 實驗方法 50
3-3-1 導電玻璃與藥品之前處理 50
3-3-2 有機感光材料之製備 50
3-3-3 旋轉塗佈PEDOT:PSS及有機感光層 51
3-3-4 熱蒸鍍鋁金屬電極 52
3-4 太陽電池光電化學測試 54
3-4-1 實驗裝置 54
3-4-2 光電流-電壓特徵曲線 54
3-4-3 交流阻抗法 56

第四章 利用P3HT/PCBM作為電子施受體製作太陽能電池元件之探討 57
4-1 施體-受體濃度比例最適化 57
4-2 電子傳輸層之影響 70
4-3 電洞傳輸層之影響 74
4-4 以氧化聚合方法製備PEDOT導電層之探討 76
4-4-1 溶劑對於氧化聚合PEDOT元件之影響 78
4-4-2 Imidazol比例對於氧化聚合PEDOT元件之影響 81
4-5 在手套箱中製作元件 86

第五章 結論與未來改進方向 90
5-1 結論 90
5-1-1 施體-受體濃度比例最適化 90
5-1-2 電子傳輸層之影響 90
5-1-3 電洞傳輸層之影響 91
5-1-4 溶劑對於氧化聚合PEDOT元件之影響 91
5-1-5 Imidazol比例對於氧化聚合PEDOT元件之影響 92
5-1-6 在手套箱中製作元件對於元件效率之影響 92
5-2 未來改進方向 93

第六章 參考文獻 95

附錄A Air mass能量計算方式 101
附錄B元件製作歷程 104

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