Self-trap-state-adjustable photoluminescence of quasi-one-dimensional RbPbI3 and Cs substitutional counterparts

The “self-trap state” in low demensional halide perovskites usually induces highly efficient below-gap broadband luminescence, which makes them promising fluorescence emitting materials. However, the luminescence mechanism based on the “self-trap state” is not well understood as yet. In this work, solution-grown quasi-one-dimensional RbPbI3 crystals reveal a large Stokes shift of ∼0.57 eV, wide and strong luminescence, and a linear power-dependent luminescence, whose luminescence mechanism was attributed to the formation of a “self-trap state” in RbPbI3. Furthermore, Cs substitutional counterpart (RbxCs1−x)PbI3 crystals were found to adjust the distortions of the PbI6 octahedron and the self-trap-state-induced luminescence properties. Our work provides a new strategy to control the “self-trap-state”-induced luminescence in low demensional halide perovskite materials.