Five-in-one: Dual-mode ultralong persistent luminescence with multiple responses from amorphous polymer films

Abstract

Organic persistent luminescence (OPL) with multi-dimensional stimuli-response has attracted increasing interests due to its wide potential applications in sensing, optical devices and bio-imaging. Herein, we report a rational design to achieve time-, temperature-, humidity- and excitation-dependent OPL based on a single organic phosphor and amorphous polymer. Amorphous polymer films with dual-mode OPL are facilely fabricated by combining doping strategy and confinement effect. Intriguingly, the OPL with a high efficiency of 20.1% consists of concomitant blue delayed fluorescence (DF) and green room-temperature phosphorescence (RTP) with ultralong lifetimes of 548 ms and 1152 ms, respectively. The conspicuous difference between the DF and RTP in emission wavelength, lifetime, and stimuli-response endows the materials with abundant variations upon applying external stimuli such as humidity and excitation. This enables a five-in-one, in-situ and reversible responsive organic afterglow system including dual-mode afterglow, time-, temperature-, excitation- and humidity-dependent afterglow color. The applications of the sensitive OPL materials for temperature measuring, in-situ humidity sensing, anti-counterfeiting and data encryption with high security levels are demonstrated. These strategies enable color-tunable OPL that responds to independent stimuli, paving the way for its multi-functional applications with high performance.