Simulation of photon recycling in ultra-thin solar cells

Abstract

A comprehensive quantum-kinetic simulation framework considering both the optical confinement and the electronic effects of finite size and strong built-in fields is introduced to assess the impact of photon recycling on the photovoltaic performance of ultra-thin absorber solar cells. The radiative recombination accounts for the actual photon density of states that is modified by cavity effects and plasmonic resonances, and via coupling to a quantum transport formalism, the impact of photon recycling is propagated from rigorous wave optical simulation of secondary photogeneration directly into a modification of the current–voltage characteristics of the full photovoltaic device. The self-consistent microscopic treatment of the interacting electronic and optical degrees of freedom in a functional device context elucidates the impact on photovoltaic performance of nanoscale device design in terms of band profiles and contact layers by revealing their effect on the radiative rates and currents. As an example, plasmonic losses related to metallic reflectors are identified in both, emission and re-absorption, and partial mitigation is achieved via dielectric passivation or detaching of the reflector.