Aggregation-Dependent Modulation of Fluorescence Colors

This study presents a feasible strategy to modulate fluorescence colors by modulating the molecular aggregation states. It is found that TPA-BODIPY, a derivative of the fluorescent dye BODIPY, can exhibit three distinct fluorescence colors depending on its aggregation state: a strong pure green emission with narrow full-width at half maxima (FWHM) of 23 nm in the monomer state, a pure yellow emission with FWHM of 33 nm in amorphous state, and a pure red emission with FWHM of 45 nm in crystal state. The small vibronic coupling and distinct electronic excitation process of the monomer and aggregates are elucidated by reorganization energy and time-dependent density functional theory. Through manipulating these aggregation states in polymer matrices, this study has successfully achieved modulation of fluorescence colors from 520 to 645 nm with narrow FWHM in polymer composites. The polymer composites can be conveniently manufactured into various intricate fluorescent patterns for information encryption. Moreover, the polymer composites with high-purity fluorescence can be used as color conversion layers, applied in light-emitting devices (LEDs) to achieve high performance with 123% of the National Television System Committee (NTSC) color gamut and 99.5% coverage.