Quantum-kinetic perspective on photovoltaic device operation in nanostructure-based solar cells

TL;DR

This paper presents a quantum-kinetic framework for understanding photovoltaic processes in nanostructure-based solar cells, highlighting deviations from classical models and bridging microscopic and macroscopic device physics.

Contribution

It introduces a quantum-kinetic approach that extends beyond semi-classical models to accurately describe charge carrier dynamics in nanostructured solar cells.

Findings

Quantum-kinetic models predict different absorption and emission spectra compared to classical models.

Deviations from bulk physics are significant in ultra-thin and nanostructure-based architectures.

The approach links microscopic material properties with macroscopic device behavior.

Abstract

The implementation of a wide range of novel concepts for next-generation high-efficiency solar cells is based on nanostructures with configuration-tunable optoelectronic properties. On the other hand, effective nano-optical light-trapping concepts enable the use of ultra-thin absorber architectures. In both cases, the local density of electronic and optical states deviates strongly from that in a homogeneous bulk material. At the same time, non-local and coherent phenomena like tunneling or ballistic transport become increasingly relevant. As a consequence, the semi-classical, diffusive bulk picture conventionally assumed may no longer be appropriate to describe the physical processes of generation, transport, and recombination governing the photovoltaic operation of such devices. In this review, we provide a quantum-kinetic perspective on photovoltaic device operation that reaches beyond the limits of the standard simulation models for bulk solar cells. Deviations from bulk physics are assessed in ultra-thin film and nanostructure-based solar cell architectures by comparing the predictions of the semi-classical models for key physical quantities such as absorption coefficients, emission spectra, generation and recombination rates as well as potentials, densities and currents with the corresponding properties as given by a more fundamental description based on non-equilibrium quantum statistical mechanics. This advanced approach, while paving the way to a comprehensive quantum theory of photovoltaics, bridges simulations at microscopic material and macroscopic device levels by providing the charge carrier dynamics at the mesoscale.