運用光學轉換矩陣及動態蒙地卡羅方法探究微結構形態對於高分子太陽能電池光電轉換效率的影響

Abstract

本研究將微結構形態應用至太陽能電池之主動層並且調整主動層厚度及分離區塊尺寸探討其對於光電性質的影響，我們選擇新穎且高效率的PffBT4T-2OD:PCBM太陽能電池作為本研究的系統，同時運用光學轉換矩陣及動態蒙地卡羅模擬兩種方法並搭配自洽平均場理論所得之微結構形態，分析能量轉換效率及細部光電特性，找出高效率的關鍵因素。 在調整主動層厚度的部分，我們針對Gyroid在兩組體積比上進行模擬且比較，發現其光電特性隨厚度變化之趨勢都極為類似，像是光子吸收效率在特定厚度下皆會出現峰值，使得JSC在此厚度時有較佳的表現，在FF的部分則是隨厚度上升呈現下降的趨勢，整體來說，PCE隨厚度的變化主要受到JSC所主導。針對改變分離區塊尺寸的探討，我們加入層狀及BHJ形態一同和Gyroid形態進行比較，在結構規整的形態中，JSC隨著分離區塊尺寸的上升而下降，FF則是隨之上升而提升，權衡兩者，PCE則是在特定分離區塊尺寸出現峰值；而在BHJ形態下，JSC及FF則都是在特定分離區塊尺寸有較高的數值，導致最終之PCE也是在此尺寸下有較佳的表現，其原因與孤島介面積比例息息相關。透過本研究成功將不同微結構形態應用至高分子太陽能電池，並且探討光電轉換效率之關鍵影響因素，期許提供實驗學者未來在研究上參考的依據，並且促進此領域的發展。

In this research, we applied the microstructure to the active layer of the polymer solar cells and tuned the active layer thickness and the domain size to examine its effect on the photoelectric properties. The novel and high-efficiency PffBT4T-2OD:PCBM solar cells was chosen as our subject in this study. Our simulation consists of optical transfer matrix and kinetic Monte Carlo method, and the microstructure is obtained from self-consistent mean filed theory. The results are evaluated the power conversion efficiency and detailed photoelectric characteristics to demonstrate key factors of high efficiency. In the part of modifying the active layer thickness we simulated and compared gyroid on the two volume ratios, and found that the trends of its photoelectric characteristics with thickness change are very similar. The photon absorption efficiency has a peak at a specific thickness, making JSC has a better performance at this thickness, and the FF decreases with the increase of thickness. Overall, the change in PCE with thickness is mainly dominated by JSC. For the theme of changing domain size, we added lamellar and BHJ forms to compare them with gyroid forms. Here, the forms are divided into two categories for discussion, one is the structured gyroid and lamellar, and the other is a small number of broken isolated sites BHJ morphology. In the form of regular structure, JSC declines with the increase of domain size, FF is increased with the increase of domain size, to balance the two, PCE is the peak value of the specific domain size. In the BHJ , both JSC and FF have a higher value at a specific domain size, which leads to better performance of the final PCE at this domain size. The reason is closely related to the isolated site interface ratio. Through this research, we successfully applied microstructures to polymer solar cells, and discussed the key influencing factors of power conversion efficiency, looking forward to provide experimental scholars with reference for future research and promote the development of this field.