Chemical Science and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA.
J Phys Chem B. 2010 Jan 21;114(2):742-8. doi: 10.1021/jp909135k.
Molecular packing structures and photoinduced charge separation dynamics have been investigated in a recently developed bulk heterojunction (BHJ) organic photovoltaic (OPV) material based on poly(thienothiophene-benzodithiophene) (PTB1) with a power conversion efficiency (PCE) of >5% in solar cell devices. Grazing incidence X-ray scattering (GIXS) measurements of the PTB1:PCBM ([6,6]-phenyl-C(61)-butyric acid methyl ester) films revealed pi-stacked polymer backbone planes oriented parallel to the substrate surface, in contrast to the pi-stacked polymer backbone planes oriented perpendicular to the substrate surface in regioregular P3HT [poly(3-hexylthiophene)]:PCBM films. A approximately 1.7 times higher charge mobility in the PTB1:PCBM film relative to that in P3HT:PCBM films is attributed to this difference in stacking orientation. The photoinduced charge separation (CS) rate in the pristine PTB1:PCBM film is more than twice as fast as that in the annealed P3HT:PCBM film. The combination of a small optical gap, fast CS rate, and high carrier mobility in the PTB1:PCBM film contributes to its relatively high PCE in the solar cells. Contrary to P3HT:PCBM solar cells, annealing PTB1:PCBM films reduced the device PCE from 5.24% in the pristine film to 1.92% due to reduced interfacial area between the electron donor and the acceptor. Consequently, quantum yields of exciton generation and charge separation in the annealed film are significantly reduced compared to those in the pristine film.
最近开发的基于聚（噻吩并噻吩-苯并二噻吩）（PTB1）的本体异质结（BHJ）有机光伏（OPV）材料具有超过 5%的太阳能电池器件功率转换效率（PCE），其分子堆积结构和光致电荷分离动力学已被研究。PTB1：PCBM（[6,6]-苯基-C（61）-丁酸甲酯）薄膜的掠入射 X 射线散射（GIXS）测量显示，与规则 P3HT [聚（3-己基噻吩）]：PCBM 薄膜中垂直于基底表面的堆积聚合物主链平面相反，π堆积聚合物主链平面平行于基底表面取向。相对于 P3HT：PCBM 薄膜，PTB1：PCBM 薄膜中的电荷迁移率约高 1.7 倍，这归因于堆积取向的差异。在原始 PTB1：PCBM 薄膜中的光致电荷分离（CS）速率比在退火的 P3HT：PCBM 薄膜中快两倍以上。PTB1：PCBM 薄膜中光学带隙小、CS 速率快、载流子迁移率高的组合，使其在太阳能电池中具有相对较高的 PCE。与 P3HT：PCBM 太阳能电池相反，退火 PTB1：PCBM 薄膜由于电子给体和受体之间的界面面积减小，使器件 PCE 从原始薄膜的 5.24%降低至 1.92%。因此，与原始薄膜相比，退火薄膜中激子产生和电荷分离的量子产率显著降低。
