Trap State Induced Recombination Effects on Indoor Organic Photovoltaic Cells

Organic photovoltaic (OPV) cells have shown effectiveness as off-grid power entities to drive the low power consumption electronics among the Internet of Things. The trap states and the induced recombination in OPV cells are critically relevant to the photovoltaic performance but remain ambiguous in OPV cells for indoor application. Here, we investigate the trap effects on the indoor photovoltaic performance by employing PBBD-T series donors and wide bandgap acceptor BTA3. It is revealed that the discrete density of state in OPV cells introduces low-lying trap states and further aggravates the trap-induced recombination. Instead of the domination of bimolecular recombination under solar radiation, trap-induced recombination prevails under indoor scenarios because of the low level of carrier densities under indoor weak illuminations. This work illustrates the details of charge carrier recombination behavior in OPV cells for indoor application and points out the importance of trap controlling in achieving high-performance indoor OPV cells.