本研究以P3HT:PCBM作為有機太陽能電池的主動層材料，首先使用兩種不同PSS/PEDOT比例的電洞傳輸層AI4083 及PH500 PEDOT:PSS，探討其對主動層垂直成分分佈的影響。接著在主動層及陰極金屬鋁之間加入五種不同的界面層: ZnO、TiO2、Al2O3、氧化鋅奈米粒子(ZnO NPs) 以及 LiF，試圖增加有機太陽能電池的短路電流及開路電壓。
實驗使用紫外光-可見光光譜來觀察主動層中P3HT分子的共軛長度變化情形，以X光繞射分析偵測P3HT及兩種不同製程ZnO的結晶程度，並以接觸角分析儀量測各種薄膜的接觸角並換算其表面能，藉由表面能來判斷主動層表面成分分佈的情形，進而推得主動層中垂直成分分佈的狀況。利用原子力顯微鏡來觀察主動層上覆蓋不同界面層時的表面型態，並且經由相影像(phase image)來觀察主動層P3HT:PCBM混合薄膜中相分離的情況。此外使用表面電位儀可量測陰極金屬鋁的功函數。太陽能電池的光電轉換效率以及各項特徵參數是利用太陽能模擬器搭配雙極性電源電表量測得到的。
經由接觸角分析所量測，可算得P3HT及PCBM薄膜表面能分別為29.20 mJ/m2以及56.77 mJ/m2。同樣藉由接觸角量測，當使用AI4083 PEDOT:PSS為電洞傳輸層時P3HT:PCBM主動層的表面能為29.92 mJ/m2，十分接近於P3HT的表面能，顯示此時P3HT:PCBM混合薄膜中表面成分多為P3HT，亦即主動層底部多為PCBM；當使用PH500 PEDOT:PSS時主動層的表面能為34.95 mJ/m2，相較於使用AI4083 PEDOT:PSS為電洞傳輸層，此時主動層中表面的P3HT比例降低，主動層底部的PCBM朝表面移動而提高表面PCBM/P3HT的比例。此主動層垂直分佈不同的原因，應與AI4083 PEDOT:PSS所含PSS比例較高，PSS與PCBM間的偶極偶極力較大相關。
使用AI4083或PH500 PEDOT:PSS當作電洞傳輸層，插入一層界面層於主動層及陰極之間後，電性變化趨勢類似。當使用PH500 PEDOT:PSS時，使用溶液法製備ZnO、TiO2、Al2O3三種氧化物當做界面層，短路電流可分別提升至15.41 mA/cm2、13.46 mA/cm2以及11.34 mA/cm2。但添加的三種界面層對於開路電壓的提升並無效果，其開路電壓均屬於0.36~0.42 V的範圍內。當使用的界面層為ZnO NPs及LiF時，短路電流並無明顯提升，而開路電壓可分別提升至0.60 V及0.56 V。

Two kinds of PEDOT:PSS (AI4083 and PH500) with different ratio were used as hole transport layer in the P3HT:PCBM organic solar cells to investigate the vertical composition distribution of active layer. And then five interlayers (ZnO, TiO2, Al2O3, ZnO NPs, LiF) were inserted between active layer and Al cathode individually to enhance the short circuit current and open circuit voltage of organic solar cells.
UV-visible spectrophotometer was used to investigate the conjugation length of P3HT in the active layer. X-ray diffraction was employed to explore the crystallinity of P3HT and ZnO films of two different processes. Contact angle measurement was used to measure the contact angles of thin films and the contact angles were inverted into surface energies to investigate the lateral phase separation and more over, the vertical composition distribution. Atomic force microscopy was utilized to investigate the morphologies of active layers with different interlayers and the phase separation of active layers. Work function of Al cathode was extracted from surface potential microscopy. The efficiency and characteristic parameters were measured by solar simulator and multi-channel I-V test unit (Keithley 2400).
The surface energy of P3HT and PCBM thin films were 29.20 mJ/m2 and 56.77 mJ/m2 respectively via contact angle measurement. The contact angle measurement also gave the surface energy of active layer which was 29.92 mJ/m2 when using AI4083 PEDOT:PSS as hole transport layer, almost the same as the surface energy of P3HT, revealing that P3HT was rich in the surface of P3HT:PCBM blend film; that is, PCBM was rich in the bottom of active layer. The surface energy of active layer was 34.95 mJ/m2 when using PH500 PEDOT:PSS as hole transport layer, showing that the component of P3HT decreased in the surface of active layer respect to the case of using AI4083 PEDOT:PSS; that is, PCBM in the bottom of active layer moved upward to the surface and then the PCBM/P3HT ratio increased. The difference of vertical distribution of P3HT:PCBM should be attributed to the higher PSS/PEDOT ratio of AI4083 PEDOT:PSS thus larger dipole-dipole force between PSS and PCBM.
The trends of electrical characteristic were the same after inserting an interlayer between the active layer and cathode in the case of AI4083 PEDOT:PSS and PH500 PEDOT:PSS. When PH500 PEDOT:PSS was used, the short circuit current could be enhanced using solution processed ZnO, TiO2 or Al2O3 as interlayer, which were 15.41 mA/cm2, 13.46 mA/cm2 and 11.34 mA/cm2, but had no effect on the increase of open circuit voltage. The open circuit voltage were in the range of 0.36~0.42 V. Short circuit current did not increase obviously but open circuit voltage could reach to 0.60 and 0.56 V after inserting ZnO NPs and LiF as interlayer.

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