Simultaneous measurement of photocurrent and recombination emission in organic solar cell

Abstract

Charge transfer (CT) state is a key intermediate to understand recombination processes in organic solar cells (OSCs). In this study, we measured the recombination emission from the CT state under different applied voltages in OSCs and a photocurrent density flowing on the circuit simultaneously. We proposed a “photoluminescence (PL)–voltage (V) plot” that is the voltage dependence of PL intensity of the CT state. The PL–V plot includes information only from the CT state recombination at the donor/acceptor interface and is complementary to the “current density (J)–V plot” that is the most important information for evaluating OSCs. The results demonstrated that the fill factor (FF) of the PL–V plot is higher than that of the J–V plot, predicting the ideal FF of the device. Our result demonstrated that the simultaneous measurement of photocurrent and recombination emission could be a strong tool for evaluating photoconversion characteristics in OSCs.