Mitigating carrier loss in photoelectrochemical photocathodes: An approach combining optical computation and experimental validation

Abstract

Metal oxide semiconductors hold significant promise for overcoming bottlenecks in optoelectronic devices, such as stability and power density limitations. However, their performance has been severely constrained by substantial carrier losses caused by small polaron hopping mechanisms. Understanding and mitigating these losses is critical for advancing the efficiency of optoelectronic technologies. In this work, we integrate an optical transfer matrix model with quantum efficiency measurements to analyze minority carrier dynamics in p-type CuBi2O4 (CBO) photocathodes. This approach reveals significant bulk recombination losses, and improvements were achieved through a textured film approach using rapid thermal annealing. Consequently, the textured CBO photocathodes with oriented grains achieved a notable enhancement in the photoelectrochemical performance, reaching a photocurrent density of 1.96 mA cm−2. Carrier loss analysis within the film indicates that the textured films significantly increase the electrons' collection length to 83 nm and reduce the bulk loss from 80% to 70%. This work provides a quantitative analysis and collection remediations of photocarriers in photoelectronic thin films.