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Binary Sb2Se3 semiconductors are promising as the absorber materials in inorganic chalcogenide compound photovoltaics due to their attractive anisotropic optoelectronic properties. However, Sb2Se3 solar cells suffer from complex and unconventional intrinsic defects due to the low symmetry of the quasi‐1D crystal structure resulting in a considerable voltage deficit, which limits the ultimate power conversion efficiency (PCE). In this work, the creation of compact Sb2Se3 films with strong [00l] orientation, high crystallinity, minimal deep level defect density, fewer trap states, and low non‐radiative recombination loss by injection vapor deposition is reported. This deposition technique enables superior films compared with close‐spaced sublimation and coevaporation technologies. The resulting Sb2Se3 thin‐film solar cells yield a PCE of 10.12%, owing to the suppressed carrier recombination and excellent carrier transport and extraction. This method thus opens a new and effective avenue for the fabrication of high‐quality Sb2Se3 and other high‐quality chalcogenide semiconductors.

a b s t r a c tLuminescent solar concentrators are low cost photovoltaic devices, which reduce the amount of necessary semiconductor material per unit area of a solar collector by means of concentration. The device is comprised a thin plastic plate in which luminescent species (fluorophores) have been incorporated. The fluorophores absorb the solar light and radiatively re-emit part of the energy. Total internal reflection traps most of the emitted light inside the plate and wave-guides it to a narrow side facet with a solar cell attached, where conversion into electricity occurs. The efficiency of such devices is as yet rather low, due to several loss mechanisms, of which self-absorption is of high importance. This work demonstrates that type-II semiconductor hetero-nanocrystals may offer a solution to the self-absorption problem in luminescent solar concentrators.

High‐efficiency antimony selenosulfide (Sb2(S,Se)3) solar cells are often fabricated by hydrothermal deposition and also comprise a CdS buffer layer. Whereas the use of toxic materials such as cadmium compounds should be avoided, both of these issues hinder scaling up to large areas and market access. For this reason, co‐sublimation is studied as a manufacturing process for the active layer as well as the use of Cd‐free buffer layers. To further improve the power conversion efficiency (PCE), a graded bandgap profile is designed for the absorber layer. A V‐shaped graded bandgap in the Sb2(S,Se)3 absorber layer is produced on a TiO2 substrate by co‐sublimation of a controlled varying molar ratio of Sb2Se3 and Sb2S3. Moreover, increasing the Se/S ratio improves the grain size and favorable (hk1) orientations, reduces the detrimental bulk defects in Sb2(S,Se)3 films. Consequently, the optimized Sb2(S,Se)3 solar cells reach a PCE of 9.02%, which is a record value for Cd‐free Sb‐based solar cells. A PCE of 7.15% is further demonstrated for a Sb2(S,Se)3 monolithically interconnected minimodule with an active area of 12.32 cm2. This co‐sublimation graded bandgap technique provides a useful guidance for the optimization of a range of solar cells based on alloy compounds.