Reducing recombination in organic photovoltaics

Abstract

In this thesis, I consider two methods to improve organic photovoltaic efficiency: energy level cascades and promotion of triplet state excitons. The former relies on a thin layer of material placed between the active layers of a photovoltaic device to destabilize excitons. If the interfacial material is chosen properly, it can significantly improve device performance. The second method proposes to use quantum mechanical rules to reduce the rate of loss in organic photovoltaic devices. An electron in a triplet state cannot directly drop to the ground state by emitting a photon, so triplet excitons have longer lifetimes, and are thus more likely to diffuse to an interface to be dissociated. But this work suggests that, once they are at the interface, they are less likely to be dissociated than a singlet.