Long Persistent Luminescence of Melt‐Grown Bulk‐Sized Doped Organic Crystals

Abstract

Host–guest systems constitute a primary subclass of long persistent luminescent (LPL) materials. Doped organic crystals serve as model platforms to clarify the intricate effect of chromophores embedded in an ordered lattice background. However, construction of doped organic crystals through traditional solution method is restricted by drawbacks such as inhomogeneity and imprecise quantification. In this report, a series of doped organic crystals is grown by a melt growth technique with centimeter‐scale size and precisely controlled concentration and homogeneity. Although the host crystals are neutral with neither heavy atoms nor any functional groups, they show enhanced long persistent luminescence with lifetimes of nearly three orders longer than those of the pure guest molecules. Moreover, the LPL wavelength, lifetime, and quantum yield can be tuned by different host–guest combination and doping concentration. Theoretical optimizations reveal that the guest molecules are substitutively rather than interstitially embedded in the host crystal lattice. The results prove melt growth to be an effective way to build and to finely control host–guest long persistent luminescent systems.

Bulk Organic Doped p-Terphenyl Crystals for X-ray Scintillators with Low Detection Limit, Nanoseconds Decay Time, and Tunable Fluorescence

“…Host–dopant systems in organic materials offer an effective strategy to modulate the photophysical properties by designing different combinations of the host molecules and dopants . This method can achieve performance control by modulating the interactions between the dopants and host molecules, such as charge transfer characteristics and energy transfer characteristics. , Additionally, practical device fabrication and experimental studies impose high demands on the shape, size, and uniformity of scintillator materials, presenting significant challenges in growing high-quality, large-sized crystals that can be processed effectively.…”

A processable, scalable, and stable full-color ultralong afterglow system based on heteroatom-free hydrocarbon doped polymers

“…In general, the challenge to generate RTP for organic chromophores lies in the insufficient intersystem crossing (ISC) caused by weak spin-orbit coupling (SOC), ultrafast nonradiative decays, and oxygen quenching. A variety of strategies have been proposed to promote ISC processes by inclusion of heavyand/or hetero-atoms 20,27,28 and deuteration, 29,30 and to suppress nonradiative relaxations using crystal engineering, [31][32][33][34][35] host-guest doping, 2,7,36 crosslinking, 37 polymerization [38][39][40][41] and many other methods. As a result, a growing number of organic RTP materials with long-lived lifetimes (4100 ms) under ambient conditions have been reported in recent years.…”

“…In such a case, some effective strategies such as crystal engineering -where many crystalline examples have been endowed with long-lived t Phos and tunable phosphorescence 32,[52][53][54][55] -may lose their competitiveness. Indeed the confinement of crystal lattice protects radiative phosphorescence transitions from molecular vibration and oxygen quenching, 31,32,[56][57][58][59] and our group has grown inchsize RTP single-crystals; 35 but poor reproducibility caused by the tricky growth conditions and weak processability caused by the fragile nature of organic crystals, really hamper their application.…”