Imaging current paths in silicon photovoltaic devices with a quantum diamond microscope

TL;DR

This paper introduces a quantum diamond microscopy technique for spatially mapping light-induced currents in silicon photovoltaic devices, enabling detailed analysis of current paths and dynamics at micrometer and microsecond scales.

Contribution

It develops a widefield nitrogen-vacancy microscope for non-invasive, high-resolution imaging of photocurrents in PV devices, demonstrating its effectiveness on various silicon solar cells.

Findings

Micrometer-scale vector magnetic field imaging of PV devices

Time-resolved imaging of photocurrent build-up and decay

Versatile platform for PV research and analysis

Abstract

Magnetic imaging with nitrogen-vacancy centers in diamond, also known as quantum diamond microscopy, has emerged as a useful technique for the spatial mapping of charge currents in solid-state devices. In this work, we investigate an application to photovoltaic (PV) devices, where the currents are induced by light. We develop a widefield nitrogen-vacancy microscope that allows independent stimulus and measurement of the PV device, and test our system on a range of prototype crystalline silicon PV devices. We first demonstrate micrometer-scale vector magnetic field imaging of custom PV devices illuminated by a focused laser spot, revealing the internal current paths in both short-circuit and open-circuit conditions. We then demonstrate time-resolved imaging of photocurrents in an interdigitated back-contact solar cell, detecting current build-up and subsequent decay near the illumination point with microsecond resolution. This work presents a versatile and accessible analysis platform that may find distinct application in research on emerging PV technologies.