Quantum-kinetic Theory of Defect-mediated Recombination in Nanostructure-based Photovoltaic Devices

Abstract

ABSTRACTIn this paper, a quantum-kinetic equivalent of Shockley-Read-Hall recombination is derived within the non-equilibrium Green's function formalism for a photovoltaic system with selectively contacted extended-state absorbers and a localized deep defect state in the energy gap. The novel approach is tested on a homogeneous bulk absorber and then applied to a thin film photo-diode with large built-in field in the defect-rich absorber region. While the quantum-kinetic treatment reproduces the semi-classical characteristics for a bulk absorber in quasi-equilibrium conditions, for which the latter picture is valid, it reveals in the thin film case non-classical characteristics of recombination enhanced by tunneling into field-induced sub-gap states.