Bulk recombination in organic bulk heterojunction solar cells under continuous and pulsed light irradiation

Abstract

We study bulk recombination under both steady-state and time-resolved conditions by using the multiple trapping (MT) model. The MT model incorporates charge trap states with a distribution of trapping energies. Charge densities under the continuous excitation are shown to obey the power law as a function of light intensity, and the exponent is related to that obtained from the transient decay of charge densities in time-resolved experiments. The theory is applied to analyze charge densities in bulk heterojunction photovoltaic cells measured by light-induced electron spin resonance (LESR) under both continuous and pulsed light irradiation. © 2013 The Japan Society of Applied Physics.