利用低壓鄰近蒸鍍法製備高效率鈣鈦礦型太陽能電池

隨著人類的科技發展及世界石化燃料的逐漸枯竭，能源議題在這個世紀以來受到廣泛的重視，各界極力投入發展替代能源，而太陽能具有取之不盡用之不竭的優勢，再加上對環境友善，並無額外環境之附加成本，使太陽能電池的發展成為目前人類解決能源短缺的絕佳方案。在眾多的太陽能電池種類中，鈣鈦礦太陽能電池以非常快之速度竄起，在短短6年間，從效率3%提升到效率21%，使原本研究高分子及染料敏化太陽能電池的團隊紛紛投入，並將原本的技術應用在鈣鈦礦太陽能電池上，得到不錯的結果。鈣鈦礦太陽能電池除了高效率的優點，也有大面積元件製程的潛力，並能將其製作在可撓性基板上，使電池具有更多元的應用，本研究針對鈣鈦礦太陽能電池進行研究，提出低壓鄰近蒸鍍法，及實驗室自製之腔體製作太陽能電池，並有別於一般製程必須於低水養環境之手套箱製作，本製程可於大氣下完成所有步驟，達到節省生產能源及兼容可撓性基板應用，並改良製程技術以增進元件的光電轉換效率。本論文首先以溶液製程成長鈣鈦礦主動層，並使用簡單的一步驟製程步驟，將碘化鉛(PbI2)與甲基碘化胺(CH3NH3I)混合於二甲基甲醯胺(DMF)溶液使兩者均勻混和，旋塗於有導電高分子溶液(PEDOT-4083)之ITO導電玻璃，利用調變一步驟製程的濃度參數、轉速及燒結溫度來提升元件效率，並探討鈣鈦礦層其成長結晶，成功將元件轉換效率提升至10.55%。由於鈣鈦礦的生長過程中非常易受環境中氣體的影響，再加上鈣鈦礦層的形成如果太快會導致晶粒小且雜亂，使介面接觸不好將影響載子傳輸，因此發展了一套新的低壓鄰近蒸鍍法的製程，並提出MAI/PbI2/MAI之三明治結構製備鈣鈦礦層，先旋塗一層MAI，再蒸鍍上PbI2層，再使用較慢速的蒸鍍方式來成長鈣鈦礦層，應用在旋塗有PEDOT-4083之基板上，完成ITO/PEDOT-4083/Perovskite/PCBM/PEI/Ag之P/I/N結構鈣鈦礦太陽能電池，經由調整參數並優化步驟像是熱清洗及三明治結構，得到了11.03%的元件轉換效率。接著本研究將低壓鄰近蒸鍍法的製程繼續做沿用，因PEI為一層不導電材料，在過厚的PEI層下，其串聯電阻會有明顯的提升，降低填充因子，因而降低效率。故決定利用BCP更換PEI層，能有效解決其原本元件之串聯電阻過高之問題，且經過優化BCP層厚度及最佳化製程時間及退火參數後，完成ITO/PEDOT-4083/Perovskite/PCBM/BCP/Ag之P/I/N結構太陽能電池，並將元件效率提升至14.52%。最後，經由文獻所知，在有機光電元件的應用，其旋塗膜層時有一些技巧可以使主動層膜更為漂亮，像是利用異丙醇、氯苯等溶劑。故在本階段，提出在低壓鄰近蒸鍍法時，也引用類似的方式，將鈣鈦礦薄膜做一個提昇，並達到14.62%，並提升光電流。在這裡，製程有一些特色，製程皆在大氣或真空下進行，不需一般鈣鈦礦太陽能所需之低水氧環境，且為低溫下完成，是謂鈣鈦礦電池發展及在大量生產上的重大突破。

關鍵字

鈣鈦礦太陽能電池；溶液製程；一步驟製程；形貌控制；低壓鄰近蒸鍍法； PEDOT:PSS ；載子傳輸；大氣製程

並列摘要

Due to the development of technology and gradual depletion of fossil fuels, the energy issue has received wide attention in this century. The world is giving every effort to develop alternative energy. Solar energy is with inexhaustible source and also environment-friendly that it will not produce greenhouse gases. For these reason, the development of solar cells has become one of the best plan to solve the oncoming shortage of energy. Among many types of solar cells, perovskite solar cells suddenly appear on the horizon and the conversion efficiency has been improved from 3% to 21% in just six years. This makes many teams who originally study in polymer and dye-sensitized solar cells start doing research about perovskite. They apply their former techniques of polymer and dye-sensitized solar cells to perovskite solar cells and also get good results. In addition to high efficiency, perovskite solar cells have other advantages such as large area solar cells potential, possible to fabricate on flexible substrates, light weight and with multiple applications. So in this study, we are going to develop low temperature process to reduce the consumption during production. We will also optimize the methods to improve the conversion efficiency of the devices. In this research, we first applied solution processed to form the perovskite as the active layers, and use one-step process to fabricate perovskite solar cells. We dissolved the PbI2 powder and N,N-Dimethylmethyleneammonium iodide (MAI) powder in N,N-Dimethylmethanamide (DMF) solution. Spin coating the solution on the substrate which with the PEDOT-4083 on the ITO glasses. Next, we modified the concentration of perovskite solution, spin rate and annealing temperature to improve the efficiency. We analyzed the effect of interface morphology and crystalline of perovskite. In this part, we success to make the perovskite solar cells with conversion efficiency of 10.55%. In general, perovskite formed by solution process is very susceptible to the atmosphere and moisture and the formation of perovskite is too quick that causing perovskite grains become small and messy. We developed a new method and homemade-chamber called low pressure proximity evaporation technique (LP-PET) to fabricate perovskite layer. First, we raised a sandwich like structure which is MAI/PbI2/MAI to fabricate the active layer of perovskite. We used homemade chamber to slowly evaporate CH3NH3I under low pressure to form perovskite layer on the ITO substrate with a layer of PEDOT-4083. After the process we mentioned above, we can fabricate the perovskite solar cells with the traditional structure of ITO/PEDOT-4083/Perovskite/PCBM/PEI/Ag which can successfully achieve the power conversion efficiency with 11.03%. Furthermore, PEI is a material which isn’t conductive. The solar cells would get high series resistance and low fill factor with a thick PEI layer. We decided to replace the PEI layer with the material called BCP which can good apply in the structure of solar cells also can decrease the series resistance. We applied this material and utilized PET method to make traditional structure solar cells. After optimized the process parameters, we achieved an efficiency of 14.52%. In the literature, we can know that there are many techniques can make the better film of active layer of organic optical devices. They use the casting with the IPA, CB on the substrates to slow down the reaction to form a better film. Here, we try to apply the mechanism in the LP-PET process. Therefore, we put the vails with solvent inside the chamber directly and we can achieve 14.62% with a higher current density. For a low temperature process under whole atmosphere or under vacuum condition, this is a breakthrough of the perovskite solar cells and mass production.

並列關鍵字

perovskite solar cells ； solution process ； one-step process ； morphology control ； low pressure proximity evaporation technique ； PEDOT:PSS ； carrier transport ； atmosphere process

參考文獻

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利用低壓鄰近蒸鍍法製備高效率鈣鈦礦型太陽能電池

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