Impact of built-in fields and contact configuration on the characteristics of ultra-thin GaAs solar cells

TL;DR

This paper uses advanced quantum-kinetic simulations to analyze how built-in electric fields and contact configurations affect the performance of ultra-thin GaAs solar cells, revealing key factors influencing efficiency and carrier dynamics.

Contribution

It introduces a quantum-kinetic simulation approach to study the impact of built-in fields and contact design on ultra-thin GaAs solar cell performance, surpassing traditional semi-classical models.

Findings

Built-in fields significantly influence charge carrier behavior.

Contact configuration affects leakage currents and voltage losses.

Quantum simulations reveal detailed carrier dynamics in ultra-thin films.

Abstract

We discuss the effects of built-in fields and contact configuration on the photovoltaic characteristics of ultrathin GaAs solar cells. The investigation is based on advanced quantum-kinetic simulations reaching beyond the standard semi-classical bulk picture concerning the consideration of charge carrier states and dynamics in complex potential profiles. The thickness dependence of dark and photocurrent in the ultra-scaled regime is related to the corresponding variation of both, the built-in electric fields and associated modification of the density of states, and the optical intensity in the films. Losses in open-circuit voltage and short-circuit current due to leakage of electronically and optically injected carriers at minority carrier contacts are investigated for different contact configurations including electron and hole blocking barrier layers. The microscopic picture of leakage currents is connected to the effect of finite surface recombination velocities in the semi-classical description, and the impact of these non-classical contact regions on carrier generation and extraction is analyzed.