Zhang Yuewei, Wei Jinbei, Zhang Dongdong, Yin Chen, Li Guomeng, Liu Ziyang, Jia Xiaoqin, Qiao Juan, Duan Lian
Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China.
Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, P. R. China.
Angew Chem Int Ed Engl. 2022 Jan 10;61(2):e202113206. doi: 10.1002/anie.202113206. Epub 2021 Nov 30.
Multiple resonance (MR) emitters are promising for highly efficient organic light-emitting diodes (OLEDs) with narrowband emission; however, they still face intractable challenges with concentration-caused emission quenching, exciton annihilation, and spectral broadening. In this study, sterically wrapped MR dopants with a fluorescent MR core sandwiched by bulk substituents were developed to address the intractable challenges by reducing intermolecular interactions. Consequently, high photo-luminance quantum yields of ≥90 % and small full width at half maximums (FWHMs) of ≤25 nm over a wide range of dopant concentrations (1-20 wt %) were recorded. In addition, we demonstrated that the sandwiched MR emitter can effectively suppress Dexter interaction when doped in a thermally activated delayed fluorescence sensitizer, eliminating exciton loss through dopant triplet. Within the above dopant concentration range, the optimal emitter realizes remarkably high maximum external quantum efficiencies of 36.3-37.2 %, identical small FWHMs of 24 nm, and alleviated efficiency roll-offs in OLEDs.
多共振（MR）发光体有望用于具有窄带发射的高效有机发光二极管（OLED）；然而，它们在浓度引起的发射猝灭、激子湮灭和光谱展宽方面仍面临棘手的挑战。在本研究中，开发了一种空间包裹的MR掺杂剂，其荧光MR核被大量取代基夹在中间，以通过减少分子间相互作用来应对这些棘手的挑战。因此，在很宽的掺杂剂浓度范围（1-20 wt%）内，记录到了≥90%的高光致发光量子产率和≤25 nm的小半高宽（FWHM）。此外，我们证明，当夹在中间的MR发光体掺杂在热激活延迟荧光敏化剂中时，可以有效抑制德克斯特相互作用，消除通过掺杂剂三重态的激子损失。在上述掺杂剂浓度范围内，最佳发光体在OLED中实现了高达36.3-37.2%的显著高最大外量子效率、相同的24 nm小FWHM以及减轻的效率滚降。
