Majumdar Atreyee, Das Surajit, Ramakrishnan Raghunathan
Tata Institute of Fundamental Research Hyderabad 500046 India
Chem Sci. 2025 Jul 8. doi: 10.1039/d5sc02309b.
Fifth-generation organic light-emitting diodes exhibit delayed fluorescence enabled by exothermic reverse intersystem crossing due to a negative singlet-triplet gap, where the first excited singlet lies below the triplet. This phenomenon, termed delayed fluorescence from inverted singlet and triplet states (DFIST), has been experimentally confirmed only in two triangular molecules with a central nitrogen atom. Here, we report a high-throughput virtual screening of 30 797 BN-substituted polycyclic aromatic hydrocarbons (BNPAH) derived from 77 parent scaffolds with 2-6 rings. Using a multi-level workflow that combines structural stability criteria with accurate excited-state calculations, we identify the top 46 DFIST-BNPAH candidates with singlet-triplet gaps less than -0.015 eV. Notably, this set includes BN-helicenes, where inversion arises from through-space charge-transfer states. Our findings reveal new design motifs for DFIST that extend beyond known frameworks, thereby expanding the chemical space for next-generation emitters based on heteroatom-embedded aromatic systems.
第五代有机发光二极管由于单重态-三重态能隙为负，通过放热反向系间窜越实现延迟荧光，其中第一激发单重态低于三重态。这种现象被称为来自反转单重态和三重态的延迟荧光（DFIST），仅在两个含有中心氮原子的三角形分子中得到实验证实。在此，我们报告了对源自77种母体骨架、具有2至6个环的30797种硼氮取代多环芳烃（BNPAH）进行的高通量虚拟筛选。使用将结构稳定性标准与精确激发态计算相结合的多级工作流程，我们确定了单重态-三重态能隙小于-0.015 eV的前46个DFIST-BNPAH候选物。值得注意的是，这一组包括硼氮螺旋烯，其反转源于空间电荷转移态。我们的研究结果揭示了超越已知框架的DFIST新设计基序，从而扩展了基于杂原子嵌入芳香体系的下一代发光体的化学空间。
