One-shot synthesis of heavy-atom-modified carbazole-fused multi-resonance thermally activated delayed fluorescence materials

一步法合成重原子修饰的咔唑融合多重共振热活化延迟荧光材料

Efficient multi-resonance thermally activated delayed fluorescence(MR-TADF)materials hold significant potential for applications in organic light-emitting diodes(OLEDs)and ultra-high-definition displays.However,the stringent synthesis conditions and low yields typically associated with these materials pose substantial challenges for their practical applications.In this study,we introduce an innovative strategy that involves peripheral modification with sulfur and selenium atoms for two materials,CFDBNS and CFDBNSe.This approach enables a directed one-shot borylation process,achieving synthesis yields of 66%and 25%,respectively,while also enhancing reverse intersystem crossing rates.Both emitters exhibit ultra-narrowband sky-blue emissions centered around 474 nm,with full width at half maximum(FWHM)values as narrow as 19 nm in dilute toluene solutions,along with high photoluminescence quantum yields of 98%and 99%in doped films,respectively.The OLEDs based on CFDBNS and CFDBNSe display sky-blue emissions with peaks at 476 and 477 nm and exceptionally slender FWHM values of 23 nm.Furthermore,the devices demonstrate remarkable performances,achieving maximum external quantum efficiencies of 24.1%and 27.2%.This work presents a novel and straightforward approach for the incorporation of heavy atoms,facilitating the rapid construction of efficient MR-TADF materials for OLEDs.

高效的多重共振热活化延迟荧光(MR-TADF)材料在有机发光二极管(OLED)和超高清显示器中具有重要的应用前景.然而,这些材料严苛的合成条件和较低的合成产率阻碍了其实际应用.本研究介绍了一种创新的MR-TADF设计策略,即通过在材料的外围修饰硫和硒原子,实现了两种材料(CFDBNS和CFDNBSe)的一步定向硼化反应,其合成产率分别达到66%和25%,并同时增强了材料的反向系间窜跃速率.这两种发光材料在甲苯溶液中表现出最大发射波长为474 nm的超窄带天蓝色发光,其半峰宽(FWHM)均只有19 nm,在掺杂膜中的光致发光量子产率分别高达98%和99%.基于CFDBNS和CFDBNSe制备的OLED器件分别显示出最大发射波长为476和477 nm的天蓝色发光,并具有较窄的FWHM值(23 nm).此外,这些器件还表现出优异的性能,其最大外量子效率分别达到24.1%和27.2%.总之,本研究提出了一种新颖且简便的重原子引入方法,促进了高效MR-TADF材料的高效合成及在OLEDs中的应用.