Enhanced electron extraction capability of polymer solar cells via modifying the cathode buffer layer with inorganic
Zhiqi Li1, Shujun Li1, Zhihui Zhang1
1State Key Laboratory on Integrated Optoelectronics, Jilin University, College of Electronic Science and Engineering, 2699 Qianjin Street, Changchun 130012, People's Republic of China. shenliang@jlu.edu.cn guowb@jlu.edu.cn.
Abstract:
Enhanced performance of polymer solar cells (PSCs) based on the blend of poly[N-9''-hepta-decanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT):[6,6]-phenyl-C70-butyric acid methyl ester (PC71BM) is demonstrated by titanium dioxide (TiO2) interface modification via CuInS2/ZnS quantum dots (CZdots). Devices with a TiO2/CZdots composite buffer layer exhibit both a high short-circuit current density (Jsc) and fill factor (FF), leading to a power conversion efficiency (PCE) up to 7.01%. The charge transport recombination mechanisms are investigated by an impedance behavior model, which indicates that TiO2 interfacial modification results in not only increasing the electron extraction but also reducing impedance. This study provides an important and beneficial approach to develop high efficiency PSCs.
