Investigation of the Mn dopant-enhanced photoluminescence performance of lead-free CsAgInCl double perovskite crystals

The lead-free double perovskite Cs 2 AgInCl 6 is a potential candidate for LEDs, the photoluminescence performance of which is reinforced greatly by Mn doping. Here, we analyzed the geometric, electronic and photoluminescence properties of Mn-doped Cs 2 AgInCl 6 by means of first-principle calculations. We found that in the interior of Cs 2 AgInCl 6 , the Mn dopant formed defect complexes by substituting an Ag atom and generating an Ag vacancy (Mn Ag V Ag ) owing to the charge balance and the weak distortion of the metal octahedra. The Mn Ag V Ag defect introduced two defect bands in the forbidden gap, which was contributed predominantly by the 3d orbitals of the Mn 2+ ions. The electron transition of the Mn 2+ ions from the first excited state to the ground state, i.e. , from 4 T 1 to 6 A 1 states, gives rise to the PL spectrum that is lower than the bandgap. Therefore, we show that the Mn dopant indeed reinforces the PL performance of Cs 2 AgInCl 6 greatly and is beneficial for its use as an LED material. The photoluminescence performance of Cs 2 AgInCl 6 is enhanced by the Mn dopant via transition from the 4 T1 state to the 6 A 1 state.