Record-breaking solar-to-hydrogen conversion tech cuts costs by 70%

Researchers from China have developed an advanced precursor seed layer engineering (PSLE) technique to significantly improve the performance of copper zinc tin sulfide (CZTS) photocathodes for solar-to-hydrogen (STH) conversion. CZTS, composed of earth-abundant elements, has been limited by defects and inefficient charge carrier dynamics, capping its efficiency below 8%. The PSLE method enhances crystal growth, reduces defect density to 9.88 × 10^15 cm^-3, and increases minority-carrier lifetime to 4.40 ns, resulting in a record half-cell solar-to-hydrogen efficiency of 9.91%. This approach also enabled the first unbiased CZTS-BiVO4 tandem cell to achieve 2.20% STH efficiency in natural seawater. The optimized CZTS films exhibit large, compact, uniform, and vertically aligned grains, which improve the CZTS/CdS heterojunction by increasing built-in voltage and lowering interfacial defects