Charge carrier losses of organic solar cells based on Subphthalocyanine/C60 heterojunction

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(P)A) 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.