Density of trap states in organic photovoltaic materials from LESR studies of carrier recombination kinetics

The density of trap states in donor/acceptor blends of organic photovoltaic materials is obtained from photogenerated charge-carrier recombination kinetics observed by light-induced electron spin resonance (LESR) at different temperatures. The method, based on an inversion calculation, is applied to experimental LESR data from two P3AT-PCBM blend films with different kinetic behavior, deriving density-of-states profiles and values of the trap depths in agreement with previous literature results obtained using other techniques.