Enhanced luminescence and energy transfer in Mn2+ doped CsPbCl3−xBrx perovskite nanocrystals

Abstract

Manganese ion (Mn²⁺) doped CsPbCl_3−xBr_x nanocrystals (NCs) with dual emissions have emerged as a promising candidate for white light emitting devices. The luminescence properties of Mn²⁺ doped CsPbCl_3−xBr_x NCs were studied by steady-state and time-resolved photoluminescence (PL) spectroscopy at temperature ranging from 80 to 300 K. The Mn²⁺ doped NCs with varied Br compositions were synthesized by means of Cl-to-Br anion exchange. The obtained doped NCs exhibited a tunable narrow band-edge emission band from 405 to 500 nm with a lengthened PL lifetime and a wide Mn²⁺ emission band at 600 nm with a shortened PL lifetime as the Br composition increases. It was interestingly found that PL intensity of the Mn²⁺ emission band was significantly enhanced by replacing Cl ions with Br and reached the maximum value in Mn²⁺:CsPbCl_2.15Br_0.85 NCs. Especially at low temperature (80 K), the intensity ratios of Mn²⁺ emission to band-edge emission increased ∼80 times in Mn²⁺:CsPbCl_2.15Br_0.85 NCs, compared with Mn²⁺:CsPbCl₃ ones. The temperature-dependent energy-transfer efficiencies of Mn²⁺:CsPbCl₃ and Mn²⁺:CsPbCl_2.15Br_0.85 NCs from excitons in NCs to Mn²⁺ ions were obtained. The PL enhancement of Mn²⁺ in CsPbCl_3−xBr_x NCs was attributed to Br composition-dependent exciton energy transfer to Mn²⁺.