Experimental design of (Cs,Rb)2Sn(Bi)Cl6 blue phosphors by cation-substitution-induced lattice strain

Abstract

A mild high-throughput synthesis of doubly substituted (Cs_xRb_1−x)₂Sn_yBi_1−yCl₆ perovskites yields single-phase solid-solution compounds in the compositional domain of x = 0–1 and y ≥ 0.75. Bi-substituted compounds emit relatively intense and broadband blue photoluminescence (PL) peaked at 455 nm, originating from the self-trapped excitonic states. Both Sn/Bi and Cs/Rb substitutions were found to exert a lattice strain with the maximal strain magnitudes observed close to x = 0.5 and y = 0.90. The PL parameters of the single-phase (Cs_xRb_1−x)₂Sn_yBi_1−yCl₆ samples, in particular, the PL intensity and lifetime, as well as the rate constants of radiative and non-radiative recombination, correlate with the strain magnitude.