以末端氨基的小分子作為氧化鋅奈米柱表面修飾劑在有機/無機混合太陽能電池中的效果

Abstract

介面性質是聚合物/半導體金屬氧化物混摻太陽能電池的一項重要課題，雖然此元件結合了有機半導體和無機半導體兩者材料的優點，但卻因為介面性質的不同，而降低了有機太陽能電池的效能。 為了克服這個困難，我們利用兩個分子結構相似的疏水性分子2-氨基蒽(2-aminoanthracene，2-AA)及4-氨基-p-三聯苯(4-amino-p-terphenyl，4-A-p-T)，以這兩個分子來修飾氧化鋅奈米柱表面的特性，以增加聚合物和金屬氧化物材料間的相容性。值得被一提的是，因為氧化鋅會被酸性分子侵蝕，故我們選用2-氨基蒽及4-氨基-p-三聯苯，以這兩種鹼性導電小分子來做氧化鋅表面改質。我們先在銦錫氧化物(ITO)玻璃上，利用水熱法長上氧化鋅奈米柱(ZnO-nanorod)，接著在已利用2-氨基蒽分子及4-氨基-p-三聯苯分子修飾過後的氧化鋅奈米柱上用旋轉塗佈的方式鋪上混和均勻的高分子（P3HT:PCBM）為主動層，最後鍍上銀當電極，完成我們的元件。 我們發現在利用2-氨基蒽分子及4-氨基-p-三聯苯分子做表面修飾之後，與未用此分子修飾過的太陽能電池元件相比，結果分別是開路電壓（Voc）為0.53 V、0.57 V，短路電流密度（Jsc）為9.52 mA/cm2、9.78 mA/cm2，填充因子（FF）為45.44 %、46.65 %，效率提升約20 %、40 %。 以2-氨基蒽分子及4-氨基-p-三聯苯分子做表面修飾之後，光吸收效率並未改變，但主動層表面較粗糙，而增加了與銀電極的接觸面積，降低了串聯電阻(series resistance，RS)，所以電流增加而提升了整個元件效能。

Hybrid solar cell is a photovoltaic that combines both organic semiconductors and inorganic semiconductors. Although it has the benefit from both materials, the different surface properties between the semiconducting metal-oxides and polymers is a critical issue that causes the device performance to deteriorate. In order to overcome the above difficulty, we use two hydrophobic molecules, 2-aminoanthracene (2-AA) and 4-amino-p-terphenyl (4-A-p-T), to enhance the compatibility between the polymer blend and metal-oxide materials. It is worth mentioning that because ZnO may be eroded by acid molecules, we use two small alkaline conductive molecules, 2-AA and 4-A-p-T, to modify the ZnO-nanorod surface. The structure of our studied cell is ITO/ZnO-nanorod/2-aminoanthracene or 4-amino-p-terphenyl/poly(3-hexythiophene):(6,6)-phenyl C61 butyric acid methyl ester (P3HT:PCBM)/Ag. It is found that after the surface is modified by 2-AA and 4-A-p-T, the cells yield an open circuit voltage of 0.53 and 0.57 V, a short circuit current density of 9.52 mA/cm2 and 9.78 mA/cm2, a fill factor of 45.44 % and 46.65 % leading to increased power conversion efficiencies by about 20 % and 40 %, respectively. Since there is no significant change in the light absorption efficiency after surface modification, the increase in the surface roughness of the photoactive layer after treatment provides a larger charge collection area. Thus, the series resistance of the devices decreases resulting in improved device performance.