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Organic heterostructures (OHSs) consist of organic micro/nanocrystals are of essential importance for the construction of integrated optoelectronics in the future. However, the scarcity of materials and the problem of phase separation still hinder the fine synthesis of OHSs. Herein, based on the αphase one-dimensional (1D) microrods and the βphase 2D microplates of one organic compound 3,3′-((1E,1′E)-anthracene-9,10-diylbis(ethane-2,1-diyl))dibenzonitril (m-B2BCB), we facilely synthesized the OHSs composed of these two polymorph phases, whose growth mechanism is attributed to the low lattice mismatch rate of 5.8% between (001) plane of αphase (trunk) and (010) crystal plane of βphase (branch). Significantly, the multiport in/output channels can be achieved in the OHSs, which demonstrates the structure-dependent optical signals with the different output channels in the OHSs. Therefore, our experiment exhibits the great prospect of polymorphism in OHSs, which could provide further applications on multifunctional organic integrated photonics circuits.

Multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters can enable narrowband emission with high color purity and electroluminescence efficiency. Nitrogen/carbonyl (N/C=O) system is receiving increasing attention while the nitrogen/ boron (N/B) system has been widely studied. Donor decoration is an effective approach for N/B type MR-TADF system but always leads to broadening and red-shifting of the emission band in N/C=O MR-TADF system. We attribute these unfavorable phenomena to the formation of intramolecular charge transfer between the MR-core and peripheral donors. To address this issue, we have developed a new strategy by decorating DMQAO(a fused N/C=O MR-core) with a triazine acceptor and a neutral terphenyl group to construct MTDMQAOand MBDMQAO, respectively. The introduction of the triazine acceptor not only realizes efficient narrowband emission in MTDMQAO, but also accelerates the reverse intersystem crossing process through enhanced spin-orbital coupling. As a result, MTDMQAOexhibits a significantly higher external quantum efficiency of 29.4% compared to the referent emitters, validating the rationality of our derivation strategy. This study highlights the potential of the N/C=O system for MR-TADF emitters and provides important insights for understanding the difference between N/B and N/C=O systems.

Three emissive bridged-triphenylamine derivatives are designed and synthesized by incorporating carbon (DQAO), oxygen (OQAO), and sulfur (SQAO) atoms with two carbonyl groups. The fully bridged geometry and unique frontier molecular orbital distribution reveal its potential as narrowband thermally activated delayed fluorescence emitters. DQAO-, OQAO-, and SQAO-based organic light-emitting diodes exhibit the maximum external quantum efficiency (EQEmax) of 15.2%, 20.3%, and 17.8% for blue, green, and yellow, respectively.

Intramolecular spatial charge transfer (ISCT) plays a critical role in determining the optical and charge transport properties of thermally activated delayed fluorescence (TADF) materials. Herein, a new donor/acceptor-type TADF compound based on rigid dibenzothiophene sulfone (DBTS) moiety, STF-DBTS, was designed and synthesized. Fluorene unit was used as a rigid linker to position the rigid acceptor and donor subunit in close vicinity with control over their spacing and molecular structure and to achieve high photoluminescence quantum yield (∼53%) and TADF property. For comparison purposes, we constructed the more flexible STF-DPSwith a less rotationally constrained diphenylsulphone (DPS) acceptor instead of the rigid DBTS units, and STF-DPSshowed no TADF properties and lower PLQY (16.0%). Organic light-emitting diodes (OLEDs) based on STF-DBTSachieve an external quantum efficiency (EQE) of 10.3% at 488 nm, which is a fivefold improvement in EQE with respect to STF-DPS.