Designing Atomic Interface in Sb<sub>2</sub>S<sub>3</sub>/CdS Heterojunction for Efficient Solar Water Splitting
Minji Yang, Zeyu Fan, Jinyan Du, Chao Feng, Ronghua Li, Beibei Zhang, Nadiia Pastukhova, Matjaž Valant, Matjaž Finšgar, Andraž Mavrič, Yanbo Li
Abstract
Abstract In the emerging Sb 2 S 3 ‐based solar energy conversion devices, a CdS buffer layer prepared by chemical bath deposition is commonly used to improve the separation of photogenerated electron‐hole pairs. However, the cation diffusion at the Sb 2 S 3 /CdS interface induces detrimental defects but is often overlooked. Designing a stable interface in the Sb 2 S 3 /CdS heterojunction is essential to achieve high solar energy conversion efficiency. As a proof of concept, this study reports that the modification of the Sb 2 S 3 /CdS heterojunction with an ultrathin Al 2 O 3 interlayer effectively suppresses the interfacial defects by preventing the diffusion of Cd 2+ cations into the Sb 2 S 3 layer. As a result, a water‐splitting photocathode based on Ag:Sb 2 S 3 /Al 2 O 3 /CdS heterojunction achieves a significantly improved half‐cell solar‐to‐hydrogen efficiency of 2.78% in a neutral electrolyte, as compared to 1.66% for the control Ag:Sb 2 S 3 /CdS device. This work demonstrates the importance of designing atomic interfaces and may provide a guideline for the fabrication of high‐performance stibnite‐type semiconductor‐based solar energy conversion devices.