External Heavy-Atom Activated Phosphorescence of Organic Luminophores in a Rigid Fluid Matrix

Abstract

Growing attention has been paid to pure organic room-temperature phosphorescence (RTP). Although an insufficient population and fast nonradiative decay of triplet excitons are avoided in recent endeavors, complicated synthesis and limited universality still hinder its development. Further, fluid RTP materials are more difficult to design because of faster nonradiative relaxation. Herein, a deep eutectic mixture of glucose and choline, a stable supercooled liquid at room temperature, is employed as a matrix. Direct transformation from commercial fluorescent dyes to RTP fluid is realized by doping without modifications. The excited triplet states are generated by an external heavy atom, while the rigid noncovalent network stabilizes them with both functions intrinsic to the liquid matrix. Modulation of matrix components also results in nearly white light emission of a single dye. This study presents a general strategy to design fluid RTP materials starting from the vast library of fluorophores.

Functional Roles of Polymers in Room‐Temperature Phosphorescent Materials: Modulation of Intersystem Crossing, Air Sensitivity and Biological Activity

“…As for the delayed emission spectrum, the 441 band is completely wiped off, indicating that it is probably a fluorescent state (S 1 ) and the band at room temperature is from thermally activated delayed fluorescence (TADF). [28] To further confirm the conclusion from PL spectra, the luminescence lifetimes of each band were measured at both RT and 77 K. At RT, we found that the fitted lifetime collected at 441 nm has two components, i.e., τ 1 = 1.26 ns and τ 2 = 80.6 ms (Figure S58). At 77 K, a single component of τ 1 = 1.81 ns is present, which clearly points to the TADF mechanism.…”

Time‐dependent Phosphorescence Color of Carbon Dots in Binary Salt Matrices through Activations by Structural Confinement and Defects for Dynamic Information Encryption

“…However, this does not conform to the conventional principle of heavy atom-enhanced phosphorescence. [51][52][53] Therefore, this further proves the confinement contribution of the inorganic matrix to RTP. The doping of metal ions will affect the change of the inorganic matrix lattice, as confirmed by XRD (Figure 6F and Figure S29).…”

“…The phosphorescence lifetime is also gradually reduced (Figure S28 and Table S4). However, this does not conform to the conventional principle of heavy atom‐enhanced phosphorescence [51–53] . Therefore, this further proves the confinement contribution of the inorganic matrix to RTP.…”

Recent Advances of Pure Organic Room Temperature Phosphorescence Based on Functional Polymers

“…Ma and Tian et al 44 used a kind of deep eutectic supramolecular polymer (DESP) to prepare supramolecular polymer-based RTP materials (Figure 5b). The transparent DESP 45 was made of hydrogen bonding interaction by using βcyclodextrin as hydrogen bond acceptor and natural organic small molecule acid (malic acid or citric acid) as hydrogen bond donor. The network is rich in hydrogen bonds, making it high viscosity and flowability, which is beneficial for promoting RTP.…”