Temperature-Dependent Reversible Afterglow Between Green, Orange, and Red in Dual-Delay Organic Doped Material

Abstract

Achieving a wide-range color-tunable and dynamically long-afterglow emission in a single-doped system remains a challenge. In this study, a unique host-guest doped material, TPA-PTPQ/TPA, exhibits dual-delay emission at 516 and 605 nm, both with long lifetimes of up to 108 and 145 ms, which derives from thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) mechanisms, respectively. Notably, this host-guest material demonstrates a temperature-dependent dynamically reversible afterglow characteristic, transitioning green, orange, and red with a substantial spectra shift of ≈90 nm under different temperature conditions. This phenomenon is due to the diverse temperature effect on TADF and RTP emissions. These remarkable luminescence properties are successfully applied in security checks and anti-counterfeiting encryption. This study provides valuable insights into the design of dynamically reversible dual-delay-emissive long-afterglow luminescent materials based on a host-guest doping system.