Gorgon Sebastian, Murto Petri, Congrave Daniel G, Matasovic Lujo, Bond Andrew D, Riesgo-Gonzalez Victor, Myers William K, Bronstein Hugo, Friend Richard H
Cavendish Laboratory, University of Cambridge, JJ Thomson Ave, Cambridge, CB3 0US, UK.
Centre for Advanced Electron Spin Resonance, Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, S Parks Rd, Oxford, OX1 3QR, UK.
Adv Mater. 2025 Jul;37(30):e2501164. doi: 10.1002/adma.202501164. Epub 2025 May 15.
High-spin states in organic molecules offer promising tuneability for quantum technologies. Photogenerated quartet excitons are an extensively studied platform, but their applications are limited by the absence of optical read-out via luminescence. Here, a new class of synthetically accessible molecules with quartet-derived luminescence is demonstrated, formed by appending a non-luminescent TEMPO radical to thermally activated delayed fluorescence (TADF) chromophores previously used in OLEDs. The low singlet-triplet energy gap of the chromophore opens a luminescence channel from radical-triplet coupled states. A set of design rules is established by tuning the energetics in a series of compounds based on a naphthalimide (NAI) core. Generation of quartet states is observed and the strength of radical-triplet exchange is measured. In DMAC-TEMPO, up to 72% of detected photons emerge after reverse intersystem crossing from the quartet state repopulates the state with singlet character. This design strategy does not rely on a luminescent radical to provide an emission pathway from the high-spin state. The large library of TADF chromophores promises a greater pallet of achievable emission colours.
有机分子中的高自旋态为量子技术提供了有前景的可调节性。光生四重态激子是一个被广泛研究的平台，但其应用受到缺乏通过发光进行光学读出的限制。在此，展示了一类新的具有四重态衍生发光的可合成获取的分子，它们是通过将非发光的TEMPO自由基连接到先前用于有机发光二极管（OLED）的热激活延迟荧光（TADF）发色团上形成的。发色团的低单重态 - 三重态能隙打开了一条从自由基 - 三重态耦合态的发光通道。通过调整基于萘酰亚胺（NAI）核心的一系列化合物的能量学，建立了一套设计规则。观察到了四重态的产生，并测量了自由基 - 三重态交换的强度。在DMAC - TEMPO中，高达72%的检测到的光子是在四重态通过反向系间窜越重新填充具有单重态特征的态之后出现的。这种设计策略不依赖于发光自由基来提供从高自旋态的发射途径。大量的TADF发色团有望提供更多可实现的发射颜色。
