Charge carrier losses of organic solar cells based on subphthalocyanine/C_60 heterojunction

摘要

Charge carrier losses of organic solar cells (OSCs) based on Subphthalocyanine (SubPc)/C_60 heterojunction have been studied through the measurements of incident light intensity dependent response of the device. The light intensity was varied between 0.03 and 100 mW/cm~2. The results showed that short circuit current density follows a linear dependence on light intensity (P_in), while open circuit voltage logarithmically increase with P_in with a slop of 120 mV/decade, indicating that the charge carrier losses are governed by trap-assisted recombination through interface states between donor and acceptor, with an estimated trap density of order 10~24 m~(-3). Moreover, the inverse dependence of shunt resistance (R_PA) on light intensity reveals that charge carriers are trapped in the bulk of active layer as well as at the organic/electrode interface, resulting in the decrease of fill factor (FF) with P_in.