(Zn,Ti)O Electron Transport Layer Enables the Highest Conversion Efficiency in Cd-Free Sb<sub>2</sub>Se<sub>3</sub> Photocathodes for Stable Solar Hydrogen Production.
basic_science · Level V
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- Record sourced from PubMed, PMID 41482719.
- Also identified by DOI 10.1002/adma.202518202.
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Abstract
Antimony selenide (Sb<sub>2</sub>Se<sub>3</sub>) has emerged as a promising photocathode material for photoelectrochemical (PEC)-driven solar hydrogen production due to its low toxicity, cost-effectiveness, and excellent photoelectric properties. Currently, efficient Sb<sub>2</sub>Se<sub>3</sub> photocathodes are mostly coupled with CdS electron transport layer (ETL), however, suffering from natural toxicity, parasitic light absorption, and interfacial mismatch and/or instability. In this study, we introduce a Cd-free Sb<sub>2</sub>Se<sub>3</sub> photocathode with an atomic layer deposition-processed (Zn,Ti)O ETL, which mitigates the respective limitations of binary oxides (i.e., ZnO and TiO<sub>2</sub>). The optimized (Zn,Ti)O ETL enhances electron carrier density, establishes a favorable 'spike-like' band alignment at the Sb<sub>2</sub>Se<sub>3</sub>/(Zn,Ti)O interface, significantly improves charge separation and transport efficiencies, as well as the stability. Consequently, the champion device achieves an impressive photocurrent density (J<sub>ph</sub>) of 31.1 mA/cm<sup>2</sup>, a record half-cell solar-to-hydrogen (HC-STH) efficiency of 5.27% for Cd-free Sb<sub>2</sub>Se<sub>3</sub> photocathodes, and the highest unbiased STH efficiency of 2.50% in the Sb<sub>2</sub>Se<sub>3</sub>-BiVO<sub>4</sub> tandem cell, setting a new benchmark for eco-friendly and high-performance PEC processed green hydrogen production.