Raman Aaswath, Yu Zongfu, Fan Shanhui
Ginzton Laboratory, Stanford University, Stanford, California 94305, USA.
Opt Express. 2011 Sep 26;19(20):19015-26. doi: 10.1364/OE.19.019015.
Organic bulk heterojunction solar cells are a promising candidate for low-cost next-generation photovoltaic systems. However, carrier extraction limitations necessitate thin active layers that sacrifice absorption for internal quantum efficiency or vice versa. Motivated by recent theoretical developments, we show that dielectric wavelength-scale grating structures can produce significant absorption resonances in a realistic organic cell architecture. We numerically demonstrate that 1D, 2D and multi-level ITO-air gratings lying on top of the organic solar cell stack produce a 8-15% increase in photocurrent for a model organic solar cell where PCDTBT:PC(71)BM is the organic semiconductor. Specific to this approach, the active layer itself remains untouched yet receives the benefit of light trapping by nanostructuring the top surface below which it lies. The techniques developed here are broadly applicable to organic semiconductors in general, and enable partial decoupling between active layer thickness and photocurrent generation.
有机本体异质结太阳能电池是低成本下一代光伏系统的一个有前途的候选者。然而，载流子提取限制使得需要薄的有源层，这会牺牲吸收以换取内部量子效率，反之亦然。受近期理论进展的推动，我们表明介电波长尺度的光栅结构可以在实际的有机电池结构中产生显著的吸收共振。我们通过数值证明，位于有机太阳能电池堆栈顶部的一维、二维和多级氧化铟锡 - 空气光栅，对于以聚[咔唑并噻吩 - 噻吩 - 对苯二甲酸酯 - 2,6 - 二噻吩]（PCDTBT）:聚[甲基丙烯酸甲酯 - 共 - （7,7,8,8 - 四氰基对苯二甲酰亚胺 - 对苯二甲酸酯）]（PC(71)BM）为有机半导体的模型有机太阳能电池，可使光电流增加8 - 15%。具体针对这种方法，有源层本身保持不变，但通过对其下方的顶表面进行纳米结构化而受益于光捕获。这里开发的技术一般广泛适用于有机半导体，并能够实现有源层厚度和光电流产生之间的部分解耦。
