Negative Thermal Quenching of Efficient White‐Light Emission in a 1D Ladder‐Like Organic/Inorganic Hybrid Material

Abstract : The synthesis and the optical properties of a new organic–inorganic hybrid material (C6H22N4)[Pb2Br8] (abbreviated as TETAPb2Br8) is reported here. Its ladder‐like crystal structure is built up from infinite 1D chains of corner‐sharing [Pb2Br8]4− bi‐octahedra surrounded by tetra‐protonated triethylenetetramine (abbreviated as TETA4+) organic cations. Under UV excitation, this hybrid organic–inorganic compound emits white light due to radiative recombinations of self‐trapped excitons associated with a structural distortion of the PbBr6 octahedra. Thin films of TETAPb2Br8 show a photoluminescence (PL) quantum yield of ≈11% and exhibit a Commission Internationale de l'Eclairage coordinates of (0.32, 0.37). In the low‐temperature range, the PL intensity increases with increasing temperature. This negative thermal quenching of white‐light emission is interpreted in terms of transitions between excitonic states involving an exciton–phonon interaction. The interpretations are supported by the temperature dependence of the resonant Raman scattering and by density functional theory calculations.