Revealing Fundamentals of Charge Extraction in Photovoltaic Devices Through Potentiostatic Photoluminescence Imaging

TL;DR

This paper introduces a voltage-dependent photoluminescence microscopy method to spatially resolve photocurrent in solar cells, providing detailed insights into local charge extraction and recombination effects for performance optimization.

Contribution

A novel microscopy-based approach for real-time, spatially resolved J(V) characterization of solar cells, linking microscopic charge dynamics to device performance.

Findings

Identifies non-ideal charge extraction regions in solar cells.

Links local charge dynamics to processing conditions.

Demonstrates the method's effectiveness on III-V and perovskite cells.

Abstract

The photocurrent density-voltage (J(V)) curve is the fundamental characteristic to assess opto-electronic devices, in particular solar cells. However, it only yields information on the performance integrated over the entire active device area. Here, a method to determine a spatially resolved photocurrent image by voltage-dependent photoluminescence microscopy is derived from basic principles. The opportunities and limitations of the approach are studied by the investigation of III-V and perovskite solar cells. This approach allows the real-time assessment of the microscopically resolved local J(V) curve, the steady-state Jsc, as well as transient effects. In addition, the measurement contains information on local charge extraction and interfacial recombination. This facilitates the identification of regions of non-ideal charge extraction in the solar cells and enables to link these to the processing conditions. The proposed technique highlights that, combined with potentiostatic measurements, luminescence microscopy turns out to be a powerful tool for the assessment of performance losses and the improvement of solar cells.