Intensity Modulated Photocurrent Microspectrosopy for Next Generation Photovoltaics

Small Methods. 2022 Sep;6(9):e2200493. doi: 10.1002/smtd.202200493. Epub 2022 Aug 16.

Abstract

In this report, a large-area laser beam induced current microscope that has been adapted to perform intensity modulated photocurrent spectroscopy (IMPS) in an imaging mode is described. Microscopy-based IMPS method provides a spatial resolution of the frequency domain response of the solar cell, allowing correlation of the optoelectronic response with a particular interface, bulk material, specific transport layer, or transport parameter. The system is applied to study degradation effects in back-contact perovskite cells where it is found to readily differentiate areas based on their markedly different frequency response. Using the diffusion-recombination model, the IMPS response is modeled for a sandwich structure and extended for the special case of lateral diffusion in a back-contact cell. In the low-frequency limit, the model is used to calculate spatial maps of the carrier ambipolar diffusion length. The observed frequency response of IMPS images is then discussed.

Keywords: intensity modulated photocurrent spectroscopy; laser beam induced current; metal halide perovskites; perovskite solar cells; photocurrent mapping; power conversion efficiency.