V. F. KunzelmannCHANG-MING JIANGJ. EichhornA. HenningI. IlichevaT. RiethI. D. Sharp2022-08-022022-08-022022https://www.scopus.com/inward/record.uri?eid=2-s2.0-85129819440&doi=10.1039%2fd1ta10732a&partnerID=40&md5=e06fd1053002c258687be005b320c02bhttps://scholars.lib.ntu.edu.tw/handle/123456789/616135We demonstrate a facile approach to solution-based synthesis of wafer-scale epitaxial bismuth vanadate (BiVO4) thin films by spin-coating on yttria-stabilized zirconia. Epitaxial growth proceeds via solid-state transformation of initially formed polycrystalline films, driven by interface energy minimization. The (010)-oriented BiVO4 films are smooth and compact, possessing remarkably high structural quality across complete 2′′ wafers. Optical absorption is characterized by a sharp onset with a low sub-band gap response, confirming that the structural order of the films results in correspondingly high optoelectronic quality. This combination of structural and optoelectronic quality enables measurements that reveal a strong optical anisotropy of BiVO4, which leads to significantly increased in-plane optical constants near the fundamental band edge that are of particular importance for maximizing light harvesting in semiconductor photoanodes. Temperature-dependent transport measurements confirm a thermally activated hopping barrier of ?570 meV, consistent with small electron polaron conduction. This simple approach for synthesis of high-quality epitaxial BiVO4, without the need for complex deposition equipment, enables a broadly accessible materials base to accelerate research aimed at understanding and optimizing photoelectrochemical energy conversion mechanisms. ? 2022 The Royal Society of Chemistry.Energy conversion; Energy gap; Interface states; Light absorption; Silicon wafers; Thin films; Vanadium compounds; Yttria stabilized zirconia; Yttrium oxide; Bismuth vanadates; Energy minimization; Interface energy; Polycrystalline film; Solid state transformations; Structural qualities; Subbands; Thin-films; Wafer scale; Yttria-stabilized-zirconia; Bismuth compoundsjournal article10.1039/d1ta10732a2-s2.0-85129819440