Lead bromide and ternary alkali lead bromide single crystals — growth and emission properties

Single crystals of PbBr2, RbPb2Br5 and CsPbBr3 (20 mm in diameter and 50 mm long) were grown by the Bridgman method from starting materials purified by bromination with bromine and hydrogen bromide and by zone refining and were tested by measurements of the low-temperature exciton luminescence and decay kinetics. The emission of RbPb2Br5 resembles that of PbBr2. Short (10–20 ps) decay times were found in CsPbBr3. The emission of all compounds tested is strongly influenced by defects and the exciton character from Frenkel to Wannier type going from PbBr2 to CsPbBr3.