Influence of Light Soaking on Silicon Heterojunction Solar Cells With Various Architectures

TL;DR

This study examines how light soaking affects silicon heterojunction solar cells, revealing that optimal layer thickness and UV exposure management are crucial for maintaining efficiency and that certain treatments can enhance performance.

Contribution

It provides new insights into the effects of light soaking on different device architectures and identifies conditions that prevent degradation or improve efficiency.

Findings

Light soaking improves efficiency with optimal layer thickness.

Insufficiently thick (p) layers lead to performance degradation.

Forward bias and infrared exposure increase efficiency regardless of layer thickness.

Abstract

In this article, we investigate the effect of prolonged light exposure on silicon heterojunction solar cells. We show that, although light exposure systematicallyimproves solar cell efficiency in the case of devices using intrinsic and p-type layers with optimal thickness, this treatment leads to performance degradation for devices with an insufficiently thick (p) layer on the light-incoming side. Our results indicate that this degradation is caused by a diminution of the (i/p)-layer stack hole-selectivity because of light exposure. Degradation is avoided when a sufficiently thick (p) layer is used, or when exposure of the (p) layer to UV light is avoided, as is the case of the rear-junction configuration, commonly used in the industry. Additionally, applying a forward bias current or an infrared light exposure results in an efficiency increase for all investigated solar cells, independently of the (p)-layer thickness, confirming the beneficial influence of recombination on the performance of silicon heterojunction solar cells.