Optimizing Photovoltaic Charge Generation of Nanowire Arrays: A Simple Semi-Analytic Approach

TL;DR

This paper introduces a semi-analytic method for optimizing nanowire array solar cells by using wavelength-dependent refractive indices to efficiently identify parameters that maximize absorption and efficiency, reducing reliance on intensive numerical simulations.

Contribution

It presents a novel semi-analytic approach that simplifies the optimization of nanowire arrays for solar cells based on material properties and resonant modes.

Findings

Method accurately predicts optimal array parameters.

Significantly reduces computational effort compared to numerical simulations.

Applicable to various materials and array thicknesses.

Abstract

Nanowire arrays exhibit efficient light coupling and strong light trapping, making them well suited to solar cell applications. The processes that contribute to their absorption are interrelated and highly dispersive, so the only current method of optimizing the absorption is by intensive numerical calculations. We present an efficient alternative which depends solely on the wavelength-dependent refractive indices of the constituent materials. We choose each array parameter such that the number of modes propagating away from the absorber is minimized while the number of resonant modes within the absorber is maximized. From this we develop a semi-analytic method that quantitatively identifies the small range of parameters where arrays achieve maximum short circuit currents. This provides a fast route to optimizing NW array cell efficiencies by greatly reducing the geometries to study with full device models. Our approach is general and applies to a variety of materials and to a large range of array thicknesses.