Experimental and Theoretical Investigation on Structural and Opto-electronic Properties of Fe-Doped Lead-Free Cs2AgBiCl6 Double Perovskite.

Herein, we report the synthesis of Fe-doped Cs2AgBiCl6 lead-free double perovskite with blue emission using an antisolvent method. The crystal structure, morphology, optical properties, band structure, and stability of Fe-doped double perovskites are investigated systematically. Formation of Fe-doped Cs2AgBiCl6 double perovskite is confirmed by XRD and XPS analysis. XRD and TGA shows that the Cs2AgBiCl6 double perovskite has high structural and thermal stability, respectively. FE-SEM analysis revealed the formation of dipyramidal shape Cs2AgBiCl6 crystals. Furthermore, EDS mapping shows the overlapping of Cs, Bi, Ag, Fe, and Cl elements and homogenous incorporation of Fe in Cs2AgBiCl6 double perovskite. The Fe-doped Cs2AgBiCl6 double perovskite shows a strong absorption at 380 nm. It extends up to 700 nm, suggesting that sub-bandgap states transition may originate from the surface defect of the doped perovskite material. The radiative kinetics of the crystals was studied using the TCSPC technique. Lattice parameters and band gap value Fe-doped Cs2AgBiCl6 double perovskites predicted by the DFT calculations are confirmed by XRD and UV-Visible spectroscopy analysis. Time-dependent photo-response characteristics for Fe-doped Cs2AgBiCl6 double perovskite show fast response and recovery time of charge carriers. We believe that the successful incorporation of Fe in lead-free, environmentally friendly Cs2AgBiCl6 double perovskite can open a new class of doped double perovskites with significant potential opto-electronics applications, photocatalysts, and photovoltaics.