Zhou Xiaojie, Cheng Jun, Wang Hongbo
Key Laboratory of Flexible Optoelectronic Materials and Technology (Ministry of Education), Center for International Cooperation and Disciplinary Innovation in Sustainable Chemical Engineering, School of Optoelectronic Materials and Technology, Jianghan University, Wuhan 430056, China.
Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK.
Molecules. 2025 Apr 11;30(8):1718. doi: 10.3390/molecules30081718.
Recent advances in electrochemiluminescence (ECL) leveraging thermally activated delayed fluorescence (TADF) have highlighted its potential for near-unity exciton harvesting. However, there are still very limited examples of TADF-ECL emitters. We present a rigid diboron-embedded multiple-resonance TADF emitter, which exhibits blue-green emission at 493 nm with a remarkably narrow bandwidth (FWHM = 22 nm) and minimized singlet-triplet energy gap (ΔE = 0.2 eV), achieving a 67% photoluminescence quantum yield. DFT calculations confirm the short-range charge transfer, enabling narrowband emission. Co-reactant-dependent ECL shows that tripropylamine (TPrA) improves the ECL efficiency from 11% (annihilation) to 51%, while benzoyl peroxide (BPO) yields 1% due to poor radical stabilization. ECL spectra align with photoluminescence, confirming the singlet-state dominance without exciplex interference. TPrA enhances stable radical formation and energy transfer, whereas BPO induces non-radiative losses. These findings establish molecular rigidity and co-reactant selection as pivotal factors in developing high-performance TADF-ECL systems, providing fundamental guidelines for designing organic electrochemiluminescent materials with optimized exciton harvesting efficiency.
利用热激活延迟荧光（TADF）的电化学发光（ECL）的最新进展突出了其近乎完全激子捕获的潜力。然而，TADF-ECL发射体的例子仍然非常有限。我们展示了一种刚性的嵌入二硼的多共振TADF发射体，其在493nm处呈现蓝绿色发射，具有非常窄的带宽（半高宽=22nm）和最小化的单重态-三重态能隙（ΔE = 0.2eV），实现了67%的光致发光量子产率。密度泛函理论（DFT）计算证实了短程电荷转移，实现了窄带发射。共反应物依赖性ECL表明，三丙胺（TPrA）将ECL效率从11%（湮灭）提高到51%，而由于自由基稳定性差，过氧化苯甲酰（BPO）的ECL效率仅为1%。ECL光谱与光致发光光谱一致，证实了单重态占主导地位且无激基复合物干扰。TPrA增强了稳定自由基的形成和能量转移，而BPO则导致非辐射损失。这些发现确立了分子刚性和共反应物选择是开发高性能TADF-ECL系统的关键因素，为设计具有优化激子捕获效率的有机电化学发光材料提供了基本指导。
