Broadband white light emission from one-dimensional zigzag edge-sharing perovskite†
Low dimensional organic–inorganic halide perovskites have gained a great deal of attention due to their augmented performance in optoelectronic applications, such as solid-state lighting and display. Such compounds consist of a layered structure, such as a multiquantum well structure, where the broadband white-light emission has been observed from diverse metal halide structures. Their broadband emission is ascribed to the self-trapped excitons (STE), which are generated from a deformable structure due to the strong electron-phono coupling. The intensity of the broadband emission is improved by lowing the dimensionality to a 1D perovskite due to the enhanced STE. Herein, we report zigzag edge-sharing 1D perovskites, (4-(aminomethyl)pyridinium)PbBr4 (C6H10N22+ = AMP2+), and (AMP)PbCl4, which are intrinsic deformative structures due to a zigzag connected PbBr6 (or PbCl6) octahedra. Through single crystal X-ray diffraction, we have identified the local lattice distortion from the octahedral environmental of Pb2+ in the inorganic sheet. The temperature dependent photoluminescence data indicate that the unusual broadband emission in zigzag edge sharing (AMP)PbBr4 and (AMP)PbCl4 perovskites is attributed to an intrinsic bulk property, in which photogenerated carriers cause the lattice distortion through electron–phonon coupling. When comparing two compounds, (AMP)PbCl4 gives more remarkable efficient white-light emission than (AMP)PbBr4, because the inorganic structure of (AMP)PbCl4 is a much larger distortion than that of (AMP)PbBr4, which results in a high color rendering index of 90.21. These established results allow us to systematically design white-light emitting materials from 1D perovskites by fine-tuning their crystal structures.