Highly anisotropic layered selenophosphate AgSbP2Se6: The electronic structure and optical properties by experimental measurements and first-principles calculations

•Layered selenophosphate AgSbP2Se6 single crystal was grown for the fist time in practical size.•Bridgeman method was used to synthesize high-quality AgSbP2Se6 single crystal.•XPS core-level and valence-band spectra were recorded for pristine and Ar+ ion-irradiated surfaces.•Ab-initio DFT calculations of the structural, electronic and optical properties were done and compared with XPS data.•High anisotropy of the optical constants of the AgSbP2Se6 crystal was shown theoretically. The Bridgman method was firstly applied for growing high quality layered selenophosphate AgSbP2Se6 single crystals in practical size. The comparatively high hygroscopicity of AgSbP2Se6 was observed by analyzing the XPS spectra of core and valence bands for both the pristine surfaces and the surfaces irradiated by Ar+ ions. The TB-mBJ + U calculations show that the valence band (VB) maximum of AgSbP2Se6 is mainly contributed by Ag-4d, Ag-s, and Sb/P/Se-p states. Meanwhile, the lower parts of the VB are mostly formed by the s-states of Sb, P, and Se atoms. The conduction band (CB) is dominated by Sb-4p states, and minor contribution of Se-4p, P-3s, and P-3p states. The absorption coefficient α(ω) is in the order of magnitude of 106 cm−1 in the energy range of 5–18 eV. Highly anisotropic optical properties of the AgSbP2Se6 single crystal allow suggesting its application in optoelectronic devices.