Synergistic effects of high-pressure processing and interface engineering in Sb2Se3/CdS photovoltaic devices

• High-pressure thermal treatment enhances (00l) orientation and crystallite size in Sb 2 Se 3 thin films. • Interface engineering by UV-O 3 and KCN treatments boost photovoltaic performance of Sb 2 Se 3 solar cells. • Se-atmosphere annealing yields Se-rich Sb 2 Se 3 films with improved crystallinity. • KCN treatment increases Sb 2 Se 3 surface hydrophilicity and adhesion to CdS, improving film texture. We report an innovative high-pressure post-deposition annealing for co-evaporated Sb 2 Se 3 absorber layers, demonstrating for its effectiveness for enhancing the crystallographic texture along the [00 l] direction. This process promotes growth parallel to the c -axis, favoring carrier transport and yielding highly crystalline films with crystallite sizes exceeding 100 nm. Nonetheless, despite improved structural properties, photovoltaic performance remained limited by interface quality. To address this, we implemented UV-O 3 and KCN etching treatments, which significantly enhanced the Sb 2 Se 3 /CdS interface, leading to conversion efficiencies up to 5.8 %. XPS, UPS, and contact angle measurements confirmed that these treatments selectively modify the interface without altering bulk properties. Thus, this work highlights high-pressure treatments combined with targetes interface engineering as a promising strategy for optimizing Sb 2 Se 3 -based thin-film solar cells.