Antimony sulfide-selenide (Sb2(S,Se)3) is a promising light-harvesting material for stable and high-efficiency thin-film photovoltaics (PV) because of its excellent light-harvesting capability, abundant elemental storage, and excellent stability. This study aimed to expand the application of Sb2(S,Se)3 solar cells with a substrate structure as a flexible or tandem device. The use of a hydrothermal method accompanied by a postselenization process for the deposition of Sb2(S,Se)3 film based on the solar cell substrate structure was first demonstrated. The mechanism of postselenization treatment on crystal growth promotion of the Sb2(S,Se)3 film and the defect passivation of the Sb2(S,Se)3 solar cell were revealed through different characterization methods. The crystallinity and the carrier transport property of the Sb2(S,Se)3 film improved, and both the interface defect density of the Sb2(S,Se)3/CdS interface and the bulk defect density of the Sb2(S,Se)3 absorber decreased. Through these above-mentioned processes, the transport and collection of electronics can be improved, and the defect recombination loss can be reduced. By using postselenization treatment to optimize the absorber layer, Sb2(S,Se)3 solar cells with the configuration SLG/Mo/Sb2(S,Se)3/CdS/ITO/Ag achieved an efficiency of 4.05%. This work can provide valuable information for the further development and improvement of Sb2(S,Se)3 solar cells.

Environmentally friendly lead-free Cs2AgBiBr6 double perovskites have emerged as potential materials for photovoltaic applications owing to their nontoxicity and high stability. However, the low solubility of precursors in the solution method and the deviated composition in the reported sequential evaporation process are still the challenges to obtain highly pure Cs2AgBiBr6 phase films. In this work, we proposed a single-source vapor deposition process for high-quality Cs2AgBiBr6 films with an effective thermally induced phase-controlled strategy. The microstructure, composition, and photoelectric properties of Cs2AgBiBr6 films with different heat treatments were investigated, and the phase evolution of Cs2AgBiBr6 film formation was figured out. High-phase purity, uniformity, smoothness of the surface, well-defined grain structure, and desired composition stoichiometry of Cs2AgBiBr6 films led to an optimized power conversion of 1.38% for a planar device structure with excellent stability. Our results demonstrate the feasibility of employing a single-source vapor deposition technique to fabricate high-quality double perovskite thin films, which paves the way for further development of various optoelectronic devices based on these promising lead-free semiconductors.

Antimony selenide (Sb2Se3) is currently considered as a kind of promising candidate material for photovoltaic and photoelectric devices, but there is still a large practical application challenge due to its low electrical conductivity and low charge carrier density. To overcome such problems, we adopt a homogroup Bi/Sb strategy to prepare Bi-doped Sb2Se3 semiconductors. According to the XRD, XPS, and TEM results, the Bi/Sb lattice substitution was evidenced in the grown (Bi x Sb1–x )2Se3 crystals. Moreover, the doped crystals have a direct band gap from 1.07 to 1.14 eV with different Bi contents, which allows a strong absorption of the solar spectrum. Hall test results and DFT calculation then witness the semiconductive-type alternation from p-type (at a low Bi concentration with Sb vacancies as acceptors) to n-type (at a high Bi concentration with Se vacancies as donors). With the increased carrier concentration under Bi doping, the electrical conductivity and photoresponse have been greatly improved. The (Bi x Sb1–x )2Se3 crystals then presented enhanced photocurrent density with fast response/recovery time (0.05 s/0.03 s) as well as long-term durability. The (Bi x Sb1–x )2Se3-based FTO/CdS/(Bi x Sb1–x )2Se3/Au solar cell eventually achieved a 62% improvement in device efficiency compared with the pure Sb2Se3-based one. It thus demonstrated an efficient homogroup Bi/Sb substitution strategy to enhance the performance of Sb2Se3-based photoelectric devices.

Kesterite-based Cu 2 ZnSnS 4 (CZTS) thin-film photovoltaics involve a serious interfacial dilemma, leading to severe recombination of carriers and insufficient band alignment at the CZTS/CdS heterojunction. Herein, an interface modification scheme by aluminum doping is introduced for CZTS/CdS via a spin coating method combined with heat treatment. The thermal annealing of the kesterite/CdS junction drives the migration of doped Al from CdS to the absorber, achieving an effective ion substitution and interface passivation. This condition greatly reduces interface recombination and improves device fill factor and current density. The J SC and FF of the champion device increased from 18.01 to 22.33 mA cm −2 and 60.24 to 64.06%, respectively, owing to the optimized band alignment and remarkably enhanced charge carrier generation, separation, and transport. Consequently, a photoelectric conversion efficiency (PCE) of 8.65% was achieved, representing the highest efficiency in CZTS thin-film solar cells fabricated by pulsed laser deposition (PLD) to date. This work proposed a facile strategy for interfacial engineering treatment, opening a valuable avenue to overcome the efficiency bottleneck of CZTS thin-film solar cells.

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