Efficient first-principles calculation of phonon assisted photocurrent in large-scale solar cell devices

TL;DR

This paper introduces a computationally efficient first-principles method to calculate phonon-assisted photocurrent in large-scale solar cells, emphasizing the importance of electron-phonon coupling for accurate device performance predictions.

Contribution

The authors develop a straightforward approach combining nonequilibrium Green's functions and special thermal displacements to include electron-phonon interactions in large-scale photovoltaic device simulations.

Findings

EPC significantly affects photocurrent and device efficiency predictions.

Method accurately reproduces experimental temperature and light dependence of silicon solar cells.

Including EPC prevents underestimation of key photovoltaic parameters.

Abstract

We present a straightforward and computationally cheap method to obtain the phonon-assisted photocurrent in large-scale devices from first-principles transport calculations. The photocurrent is calculated using nonequilibrium Green's function with light-matter interaction from the first-order Born approximation while electron-phonon coupling (EPC) is included through special thermal displacements (STD). We apply the method to a silicon solar cell device and demonstrate the impact of including EPC in order to properly describe the current due to the indirect band-to-band transitions. The first-principles results are successfully compared to experimental measurements of the temperature and light intensity dependence of the open-circuit voltage of a silicon photovoltaic module. Our calculations illustrate the pivotal role played by EPC in photocurrent modelling to avoid underestimation of the open-circuit voltage, short-circuit current and maximum power. This work represents a recipe for computational characterization of future photovoltaic devices including the combined effects of light-matter interaction, phonon-assisted tunneling and the device potential at finite bias from the level of first-principles simulations.