Pressure-Induced Restricting Intermolecular Vibration of a Herringbone Dimer for Significantly Enhanced Multicolor Emission in Rotor-Free Truxene Crystals br

Organic solid-state luminescent materials exhibit numerous exciting photoelectric properties that are central to emergent organic light-emitting diodes, smart sensors, and data encryption. However, the luminescence of pure organic rotor-free materials has been afflicted with strong intermolecular pi-pi stacking interactions. Herein, an unprecedented pressure-induced emission enhancement (PIEE) is realized in a system of rigid planar pure polycyclicaromatics, i.e., truxene crystals. The emission intensity is enhanced 7-fold below 3.0 GPa with aphotoluminescence quantum yield increased to 10.17% compared with the initial value of 1.78%,and the emission colors change from green (520 nm) to red (640 nm) within 11.8 GPa. Spectralcharacterizations andfirst-principles calculations reveal that the PIEE and piezochromism canmainly be attributed to the restricted intermolecular vibration and the decreased energy gap. Our findings enrich the PIEE mechanism and provide a new guideline for designing pressure-responsive luminescent materials in advancing their photoelectric applications