An Organic Laser Based on Thermally Activated Delayed Fluorescence with Aggregation‐Induced Emission and Local Excited State Characteristics

Abstract

The spatial separation between the highest occupied and the lowest unoccupied molecular orbitals (HOMO and LUMO) in thermally activated delayed fluorescent (TADF) molecules leads to charge transfer (CT) states, which degrade the oscillator strength of emission transition and sacrifices high solid-state photoluminescence quantum yield (PLQY), together limiting its application in organic solid-state lasers (OSSLs). Here, we demonstrated organic microwire lasers from TADF emitters that combine aggregation induced emission (AIE) and local excited (LE) state characteristics. The unique AIE and LE feature lead to a PLQY approaching 50 % and a high optical gain of 870 cm À 1 for TADF microwires. The regenerated singlet excitons by reverse intersystem crossing (RISC) process are conducive to population inversion. As a result, we demonstrated microwire lasers around 465 nm with a low threshold of 3.74 μJ cm À 2 . Therefore, our work provides insight to design TADF materials for OSSLs.

Clarifying the Active Site Role of meso‐Carboxyphenyl Group for Free Base Porphyrins in Photocatalytic H2 Evolution Reaction

“…By comparing Table S2, S3 and S4, it is indicated for all of three porphyrins that S5 and S6 states also receive contribution from local excitation (for example the electron transfer from HOMO‐3 to LUMO+1) besides CT excitation. It should be emphasized that local excitations contribute to charger separation much less effectively than CT excitation [17] . Furthermore, no obvious correlation between localized excitations contribution and the photocatalytic activity was observed for these three porphyrins.…”

“…It should be emphasized that local excitations contribute to charger separation much less effectively than CT excitation. [17] Furthermore, no obvious correlation between localized excitations contribution and the photocatalytic activity was observed for these three porphyrins.…”

“…For these four frontier orbits, electrons locate dominantly on central porphine ring similar to that reported in literature. [16] Whereas, the absorption bands (S5, S6, S7) in ultraviolet light region comprise intensive charger transfer (CT) excitation, [17] that is the electron transfer from HOMO/HOMO-1 to the electron orbits locating mainly on meso-carboxyphenyl group. Similar situation was also observed for H 2 TmCPP (Table S3) and H 2 TDCPP (Table S4).…”

Recent advances in organic donor–acceptor cocrystals: design, synthetic approaches, and optical applications

“…99 The TADF process is different from the local excited (LE) state in terms of formation mechanism and lifetime perspective. 100 The binary CT cocrystal microstructures were synthesized by solution assembly and exhibit well-defined 1D microrods with green emission for 3-BrTC and yellow emission for 4-BrTC under UV light (Fig. 7a-c).…”

Molecular and Aggregate Synergistic Engineering of Aggregation-Induced Emission Luminogens to Manipulate Optical/Electronic Properties for Efficient and Diversified Functions

“…Organic luminescent materials have received increasing interest due to their important applications in various fields, such as optoelectronic devices, − fluorescent bioprobes, − disease diagnosis and therapy, − and so on. The design and fabrication of luminescent materials mainly relies on the ingenious covalent modification of molecular structures under the guidance of the rule of structure–property relationship built on the molecular level .…”