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FeVO4 is a potential photoanode candidate with favorable bandgap energy for absorbing visible light in the solar spectrum. However, the achieved photocurrents are still much lower than the theoretical photocurrent due to poor bulk carrier separation efficiency. Herein, the aim is to improve FeVO4 charge transport properties by searching for suitable metal doping using combinatorial methods. Thin‐film FeVO4 libraries with different doping ratios of Zn, Ni, Cr, Mo, and W are fabricated on fluorine doped tin oxide substrates using combinatorial inkjet printing and their photoelectrochemical properties screened using photoscanning droplet cell. Mo and W doping show higher current density compared with undoped FeVO4; whereas the photocurrent decreases for Ni‐ and Zn‐doped samples. The best photocurrent is achieved with 7% doping ratio of Cr. Cr is discovered as a promising dopant for the first time, which is more effective than reported Mo or W for FeVO4 photoanode. The replacement of Cr3+ to Fe3+ in FeVO4 crystal lattice helps to mainly improve the catalytic activity for charge transfer, which results in the enhancement of photoresponse of the FeVO4 photoanode. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version Tier 2 Project (MOE2016-T2- 1-030)

Inorganic hole-transport layers (HTLs) are widely investigated in perovskite solar cells (PSCs) due to their superior stability compared to the organic HTLs. However, in p–i–n architecture when these inorganic HTLs are deposited before the perovskite, it forms a suboptimal interface quality for the crystallization of perovskite, which reduces device stability, causes recombination, and limits the power conversion efficiency of the device. The incorporation of an appropriate functional group such as sulfur-terminated surface on the HTL can enhance the interface quality due to its interaction with perovskite during the crystallization process. In this work, a bifunctional Al-doped CuS film is wet-deposited as HTL in p–i–n architecture PSC, which besides acting as an HTL also improves the crystallization of perovskite at the interface. Urbach energy and light intensity versus open-circuit voltage characterization suggest the formation of a better-quality interface in the sulfide HTL–perovskite heterojunction. The degradation behavior of the sulfide-HTL-based perovskite devices is studied, where it can be observed that after 2 weeks of storage in a controlled environment, the devices retain close to 95% of their initial efficiency. National Research Foundation (NRF) Accepted version This research was funded by the National Research Foundation, Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) program. The authors would like to acknowledge the Facility for Analysis, Characterization, Testing and Simulation, Nanyang Technological University, Singapore, for use of their XPS/UPS facilities. They would also like to thank Dr. Gonzalo Carrasco from Earth Observatory of Singapore, NTU, for his assistance in carrying out ICPMS.