以奈米結構提升有機太陽能電池效率之模擬與實驗

Abstract

本篇論文是以嘗試製作具奈米尺度之結構應用於有機太陽能電池元件中，並藉由模擬進一步探討金屬奈米結構之功用包括表面電漿子效應和光散射效應，期待對有機太陽能電池之光轉電效率能有提升之功效。 理論方面，藉由有限時域差分法計算電磁場分布及以數學軟體作資料分析進一步驗證奈米結構對有機太陽能電池效率提升之影響。例如探討不同金屬材質、大小、形狀、週期對有機太陽能電池之主動層穿透率和局域強度的變化關係。藉此設計出數種有機太陽能電池元件，確認其對有機太陽能轉換效率能否有提升之可行性。 實驗方面，主要製作三種有機太陽能電池元件，第一種為藉由化學合成之金奈米粒子加入有機太陽電池中，第二、三種則是利用電子束微影技術製作包括圓形，三角形，正方型之二維金屬奈米陣列及不同週期之一維金屬光柵於有機太陽能電池之ITO電極上，期待對有機太陽能電池效率能有提升作用。並藉由量測有機太陽能電池元件之電壓與電流曲線和光電流來探討金屬結構對效率的影響。另外，利用奈米壓印和蝕刻方式製作具週期性奈米排列之主動層結構。 最後，提出一個新的有機太陽能電池元件結構，希望藉由金屬奈米結構控制光在主動層的分佈狀況，並搭配吸光材料的位置配置關係，使得光的吸收能達到一個極值，使效率達到最佳化的結果。

We attempted to manufacture nano-scale structures which were applied in the organic solar cell in this thesis, and further we used the simulation to discuss the functions of the metallic nanostructures as surface plasmon polariton (SPP) effect and the light scattering effect. It was anticipated to utilize the enhancement of power conversion efficiency in organic solar cell. In the theoretical part, we used finite difference time domain (FDTD) to calculate the electromagnetic fields and data analysis by using MATLAB or Sigmaplot, and then confirmed the influence of the organic solar cell efficiency by metallic nanostructures. For example, we discussed different parameter as metal materials, sizes, shapes, periods to probe into transmission and localized intensity in active layer of organic solar cell. Further we designed several kinds of organic solar cell device to confirm whether it is feasible to increase power conversion efficiency or not. In the experimental part, we mainly fabricated three kinds of polymer solar cell device. The first kind is that incorporating gold nanoparticles which generated by chemical synthesis to the organic solar cell. The second, third kind of the device thatusing e-beam lithography to manufacture different shapes of nanostructure as circle, triangle and square arrays and different periodic gold grating on ITO electrode. And we measured I-V curve and IPCE to prove efficiency enhancement of organic solar cell. Besides, we tried to fabricate active layer of polymer solar cells with periodic nanostructures by nanoimprint and etching. Finally, we brought up a new organic solar cell with double nanostructures. It was expected to dominate incident light distribution of active layer via metallic nanostructure which matched main light-absorption polymer material. It will enhance light absorption heavily in active layer resulting in power conversion efficiency reach optimum value.