Ultrafast carrier relaxation and nonequilibrium phonons in hot carrier solar cells

Abstract

Third generation concepts in photovoltaic devices depend critically on the dynamics of ultrafast carrier relaxation and electron-phonon interactions on very short times scales in nanostructures such as quantum wells, wires and dots. Hot carrier solar cells in particular depend on the reduction in the energy relaxation rate in an absorber material, where hot carriers are extracted through energy selective contacts. Here we investigate the short time carrier relaxation in quantum well, hot electron solar cells under varying photoexcitation conditions using ensemble Monte Carlo (EMC) simulation coupled with rate equation models, to understand the limiting factors affecting cell performance. In particular, we focus on the potential role of hot phonons in reducing the energy loss rate in order to achieve sufficient carrier temperature for efficient performance.