Vibronic interactions in CsPbCl 3x Br 3(1-x) (x=0...1) and CsPbCl 2 J crystals

Abstract

Low temperature (T equals 5...80 K) reflection spectra at fundamental absorption edge and luminescence spectra have been measured for CsPbCl<SUB>3x</SUB>Br<SUB>3(1-x</SUB>) (x equals 0...1) and CsPbCl<SUB>2</SUB>J crystals. Some exciton parameters were estimated. Namely, the exciton binding energy for the crystal row varies from 71 to 31 meV and the ground exciton radius does in range 10.4 - 15.7 angstrom. It was found that disordering effects were insignificant for the above mentioned solid solutions. The exciton nature change condition is not satisfied in case of halide replacing. Relaxation of the intrinsic electron excitation for the investigated crystals excited in range of fundamental absorption occurs through the following ways. It is the free and trapped exciton emission and also their scattering on LO-phonons for CsPbX<SUB>3</SUB> (X equals Cl,Br) single crystals, the trapped exciton emission for the CsPbCl<SUB>3x</SUB>Br<SUB>3(1- x</SUB>) (x equals 0...1) solid solutions and the trapped and self-trapped exciton emission for CsPbCl<SUB>2</SUB>J crystals.