Charge Separation Enhancement Enables Record Photocurrent Density in Cu2ZnSn(S,Se)(4) Photocathodes for Efficient Solar Hydrogen Production
Résumé
Cu2ZnSn(S,Se)(4) (CZTSSe) is a promising light absorbing semiconductor for solar energy conversion in photovoltaic cells and photo-electrochemical (PEC) water-splitting devices, owing to its earth-abundant constituents, adjustable band-gap, and superior absorption coefficient. However, the severe charge carrier recombination and the sluggish charge separation efficiency are the main issues obstructing the enhancement of device performance. In this work, a planar-type Mo/CZTSSe/CdS/TiO2/Pt photocathode is fabricated. High-quality CZTSSe film with compact and uniform crystal grains can be obtained via a two-step process involving solution processed spin coating and thermally processed selenization. When an appropriate film thickness is used, both bulk defects and surface/interface defects are passivated, significantly suppressing the defects-assisted recombination. Moreover, the benign energy band alignment of CZTSSe/CdS heterojunction is favorable to enhance photo-generated charge separation and transfer efficiency. A remarkable photocurrent density of 40.40 mA cm(-2) (at 0 V-RHE) can be achieved, approaching to its theoretical value of 42.85 mA cm(-2), and representing the highest value reported to date for kesterites-based photocathodes. A champion CZTSSe photocathode with half-cell solar-to-hydrogen conversion efficiency of 6.47% suggests a bright future for efficient solar hydrogen production applications.
Domaines
ChimieOrigine | Fichiers produits par l'(les) auteur(s) |
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