A novel series of excited-state intramolecular proton transfer (ESIPT) emitters, namely, DPNA, DPNA-F, and DPNA-^tBu, endowed with dual intramolecular hydrogen bonds, were designed and synthesized. In the condensed phase, DPNAs exhibit unmatched absorption and emission spectral features, where the minor 0–0 absorption peak becomes a major one in the emission. Detailed spectroscopic and dynamic approaches conclude fast ground-state equilibrium among enol–enol (EE), enol–keto (EK), and keto–keto (KK) isomers. The equilibrium ratio can be fine-tuned by varying the substitutions in DPNAs. Independent of isomers and excitation wavelength, ultrafast ESIPT takes place for all DPNAs, giving solely KK tautomer emission maximized at >650 nm. The spectral temporal evolution of ESIPT was resolved by a state-of-the-art technique, namely, the transient grating photoluminescence (TGPL), where the rate of EK* → KK* is measured to be (157 fs)⁻¹ for DPNA-^tBu, while a stepwise process is resolved for EE* → EK* → KK*, with a rate of EE* → EK* of (72 fs)⁻¹. For all DPNAs, the KK tautomer emission shows a narrowband emission with high photoluminescence quantum yields (PLQY, ∼62% for DPNA in toluene) in the red, offering advantages to fabricate deep-red organic light-emitting diodes (OLED). The resulting OLEDs give high external quantum efficiency with a spectral full width at half-maximum (FWHM) as narrow as ∼40 nm centered at 666–670 nm for DPNAs, fully satisfying the BT. 2020 standard. The unique ESIPT properties and highly intense tautomer emission with a small fwhm thus establish a benchmark for reaching red narrowband organic electroluminescence.

中文翻译：

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多重烯醇-酮异构化和激发态单向分子内质子转移生成强窄带红色 OLED


设计并合成了一系列具有双分子内氢键的新型激发态分子内质子转移（ESIPT）发射体，即DPNA 、 DPNA-F和DPNA ^-t Bu 。在凝聚相中， DPNA表现出无与伦比的吸收和发射光谱特征，其中次要的 0-0 吸收峰成为发射中的主要吸收峰。详细的光谱和动力学方法得出了烯醇-烯醇（EE）、烯醇-酮（EK）和酮-酮（KK）异构体之间的快速基态平衡。可以通过改变DPNA中的取代来微调平衡比。与异构体和激发波长无关，所有DPNA都会发生超快 ESIPT，仅给出 KK 互变异构体发射在 >650 nm 处最大化。 ESIPT 的光谱时间演化通过最先进的技术解决，即瞬态光栅光致发光 (TGPL)，其中DPNA的 EK* → KK* 速率测量为 (157 fs) ^-1 - ^t Bu ，同时求解 EE* → EK* → KK* 的逐步过程，EE* → EK* 的速率为 (72 fs) ^-1 。对于所有DPNA ，KK 互变异构体发射显示出红色窄带发射和高光致发光量子产率（PLQY，甲苯中的DPNA约为 62%），为制造深红色有机发光二极管（OLED）提供了优势。由此产生的 OLED 具有较高的外量子效率， DPNA 的光谱半峰全宽 (FWHM) 窄至~40 nm，中心波长为 666–670 nm，完全满足 BT 要求。 2020年标准。 独特的 ESIPT 特性和具有小 fwhm 的高强度互变异构体发射，从而为实现红色窄带有机电致发光奠定了基准。