Broadband Emission Enhancement Induced by Self-Trapped Excited States in One-Dimensional EAPbI₃ Perovskite under Pressure

Ethylammonium lead iodide (C₂H₅NH₃PbI₃) with a unique one-dimensional structure is presented as a new organic–inorganic halide perovskite among the emerging photoactive materials. Here, we have discovered that C₂H₅NH₃PbI₃ can easily undergo structural distortion and enable a strong quantum confinement that generates double emission enhancement and gives a 5-fold enhanced broadband emission under pressure. Experimental data analyses indicate that the decrease in the conduction band energy caused by the shortening of the Pb–I bond length contributes to the first increase of the emission at 2.7 GPa. The second enhancement of the emission is triggered at 4.5 GPa, induced by the increased self-trapping depth rooting in the strong coupling between the distorted PbI₆ octahedral inorganic lattice and excitons after the phase transition from orthogonal to monoclinic structure. This work verifies that pressure is a powerful way to create one-dimensional systems favorable for exciton self-trapping for producing enhanced broadband emission, and opens up a new route toward superior light emitters based on quantum materials.