Boosting Phosphorescent Performance by a Three-Component Doping of Coumarin Derivatives, Metal Salts Into Polyvinyl Alcohol

Abstract

Multi-component doping has become an effective way to achieve efficient room-temperature phosphorescence. In this paper, green phosphorescence emission from coumarin derivatives, i.e., coumarin-3-carboxylic acid (CCA) and coumarin-3-carboxylic ester (CEt) are activated by doping them into polyvinyl alcohol (PVA) matrix (two component doping). Then, a series of metal salts (Ca²⁺, Al³⁺, Mn²⁺, and Zn²⁺) are added as the third component to construct three-component doping system, with the aim to further improve the phosphorescence properties of the polymer films. Among them, CaCl₂ can significantly increase the emission intensity (9.2 times), prolong the phosphorescence lifetime (up to 361 ms), and increase the phosphorescence quantum yield (from 1.02% to 9.19%). The results indicated that RTP emission can be activated by inhibiting the non-radiative transition of coumarin derivatives embedded in the rigid PVA matrix. RTP performance can be further enhanced relying on the coordination effect between the coumarin guests and the metal salts. This study provides a simple and effective three-component doping method for boosting polymer film-based phosphorescence performance.