Electronic confinement for tuning optical properties in β-InxTMzSy (TM = V, Fe, and Ti): Prospects for intermediate-band materials

Low energy photons absorption is observed in transition metals substituted alloys, and in InxVSy, InxFeSy, and InxTiSy thin films presented here which are in good agreement with the theoretical prediction as well as the experimental results. The peaks of additional absorption of the sub-band gap energy increase with the increasing dopants concentration. In In11VS18, In11FeS18, and In11TiS18 thin films, the transmittances exhibit the highest peaks in the visible range and show negligible variation with the absorber thickness (τ). The energy differences between Fermi level and the bottom of the conduction band in In5Ti0.33S8, In7VS12, and In5.4VS9.6 match the experimental results used for intermediate-band solar cell design, which makes them promising materials. Total energies of all structures are calculated using the most precise all electrons full potential linearized augmented plane wave plus local orbitals (FP-LAPW + lo) within the framework of DFT.