Insight into efficient photoluminescence regulation mechanism by lattice distortion and Mn2+ doping in organic-inorganic hybrid perovskites

Abstract

The space configurations of organic ammonium cations play a vital role in indirectly revealing the relationship between the structures and photoluminescence properties. Structural transformation induced tunability of the photophysical properties has rarely been reported. In this work, two organic–inorganic halide perovskites with different octahedral distortions were synthesized to explore the relationships between “steric effect” of organic cations and photoluminescence properties. The broadband emission of (DETA)PbBr5·H2O with high octahedral distortion is attributed to self-trapped excitons and trap states, whereas smaller steric hindrance ammonium cation 1,4-butanediamine form a 2D layered perovskite with narrowband emission due to free excitons. More importantly, the photoactive metal ions Mn2+ doping strategy gives rise to tunable broadband light emission from weak to strong orange emission with higher PLQY up to 20.96 % and 12.90% in 0D (DETA)Pb0.2Mn0.8Br5·H2O and 2D (BDA)Pb0.8Mn0.2Br4 respectively. Combined with time-correlated single photon counting and photoluminescence spectra, Mn-doped perovskites reveal energy transfer from host to Mn2+ characteristic energy level (4T1—6A1). Importantly, defect states are reduced by doping manganese ions in (DETA)PbBr5·H2O to enhance photoluminescence intensity. This work sheds light on the mechanism of defect-related emission and provides a successful strategy for designing novel and adjustable materials.