Performance Potential for Locally Contacted Perovskite Solar Cells

Abstract

In perovskite solar cells (PSCs), a common characteristic of highly effective interface passivation materials is low conductivity. Gains in voltage are thus often disproportionately offset by resistive losses. Local contact approaches can minimize this trade‐off and have a proven track record in conventional silicon photovoltaics. Indeed, recent record efficiencies for centimeter‐scale PSCs exploited architectures where the passivation layer partially covers the perovskite‐transport layer interface. Here, we use a three‐dimensional numerical device model to determine practical performance limits to local contact geometries and consider both the optimum contact dimensions and the trade‐offs involved in relaxing these dimensions for ease of fabrication. We observe the potential for substantial PCE increases with local contacts. In devices where power loss occurs solely through recombination at the contacted interface, PCE can be enhanced by up to 10% absolute by comparison to a full‐area contact. However, optimum PCEs depend on contacts on the order of nanometers. We show that more fabrication‐friendly micrometer‐scale contacts still boost PCE, but the absolute enhancement falls short due to the relatively low bulk perovskite charge carrier diffusion length. This may ultimately motivate methods of interface engineering that produce ‘effective’ local contact geometries at nanometer‐scales, such as via self‐forming layers.This article is protected by copyright. All rights reserved.