First-principles insights into the electronic structure, optical and band alignment properties of earth-abundant Cu2SrSnS4 solar absorber

Abstract Cu 2 SrSnS 4 (CSTS) is a promising alternative candidate to ZnSnS (CZTS) for single- or multi-junction photovoltaics (PVs) owing its efficient light-absorbing capability, earth-abundant, nontoxic constituents, and suitable defect properties. However, as novel absorber material, several fundamental properties need be characterized before further progress can made in CSTS photovoltaics. In this letter, hybrid density functional theory (DFT) calculations have been used comprehensively characterize the first time, electronic structure, band alignment, optical of CSTS. It demonstrated that possesses ideal structure (direct gap 1.98 eV small photocarrier effective masses) (high extinction coefficient wide absorption) photovoltaic applications. Simulated X-ray photoelectron spectroscopy (XPS) valence spectra using variable excitation energies show Cu-3 d state dominates maximum Furthermore, vacuum-aligned diagram between other common absorbers (CZTS, CIGS, CdTe) n -type partner materials (CdS, ZnO) was constructed, which indicate staggered type-II alignment at CSTS/CdS CSTS/ZnO interfaces. Based on these results, interface offset engineering device architectures are suggested improve charge carrier separation power conversion efficiencies