Efficiency improvement in organic solar cells by doping cholesteric liquid crystal

Abstract

A series of poly(3-hexylthiophene) (P3HT)/indene-C60 bisadduct (ICBA) bulk heterojunction polymer solar cells is fabricated with different cholesteric liquid crystalline (LC)-cholesteryl chloride doping concentrations. The open circuit voltage (Voc) is increased from 0.78 V to 0.65 V, meanwhile the short circuit current density (Jsc) is reduced from 4.23 mA·cm-2 to 4.10 mA·cm-2 when the LC doping concentration is 5%, and fill factor is almost unchanged. The optimized power conversion efficiency of polymer solar cells (PSCs) with LC doping is about 1.51%. The crystallinity of the active layer and the light absorption characteristics are analyzed by X-ray diffraction, photoluminescence, UV-visible absorption spectroscopy and atomic force microscope, respectively.