Modeling based screening for optimal carrier selective material for Si based solar cells

TL;DR

This paper uses analytical and numerical modeling to identify optimal properties of carrier selective materials for silicon solar cells, revealing that moderate band offsets and interface passivation are key for efficiency.

Contribution

It provides new insights into the effects of band alignment, interface quality, doping, and dielectric properties on carrier selective silicon solar cells, guiding material selection.

Findings

Optimal band offset is 0.2-0.4 eV for reduced recombination.

Interface passivation is less critical for minority carriers.

Doping density and dielectric constant influence performance similarly to band offset.

Abstract

Carrier selective (CS) silicon solar cells are increasingly explored using a variety of different materials. However, the optimum properties of such CS materials are not well understood. In this context, through detailed analytical and numerical modeling, here we provide several interesting insights on the efficiency tradeoff with CS material properties. First, we show that perfect band alignment is a desirable feature only if the interface is devoid of any trap states. Otherwise, a band offset of around 0.2eV-0.4eV provides sufficient band bending to reduce the effect of interface recombination, thus improving the performance. Surprisingly, the interface passivation quality for the minority carrier extraction layer is found to be far less demanding than that for the majority carrier extraction layer. Additionally, doping density and dielectric constant of CS layers have a similar effect as band offset on solar cell performance. Our results have obvious implications toward the selection of appropriate materials as carrier selective layers and hence are of broad interest to the community.