Heavy-metal-free pure organic room temperature phosphorescence (ORTP) holds great potential in the field of organic optoelectronic devices owing to low economic cost, simple preparation techniques, and high exciton utilization. However, it is still filled with challenges in realizing high efficiency organic light-emitting diodes (OLEDs) and exploring the internal physical mechanism based on these ORTP molecules. Here, a high-performance OLED induced by an unexpected interfacial spin-mixing process between the ORTP molecule and interlayers is demonstrated, and the high efficiency electroluminescence (EL) mechanism is studied through magneto–electroluminescence (MEL) and magneto–photoluminescence (MPL) measurements. The steady-state and transient PL properties imply that the interfacial effect is related to a high-lying singlet fission (HLSF) process in the ORTP molecule itself. Further, the HLSF process and the corresponding energy level position are confirmed by the incident wavelength- and temperature-dependent PL spectra and the magnetic-field-dependent transient PL. Finally, by optimizing the interfacial material adjacent to the emissive layer to utilize this interfacial spin mixing effect, a high-efficiency non-doped ORTP-OLED with external quantum efficiency of 16% and CIE coordinates of (0.27, 0.49) is developed. The proposed mechanism during the EL process will give insight to produce more efficient OLEDs based on ORTP materials in the future.

中文翻译：

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基于高位单重态激子裂变的纯有机室温磷光的高效非掺杂有机发光二极管


无重金属纯有机室温磷光 （ORTP） 具有经济成本低、制备技术简单、激子利用率高等优点，在有机光电器件领域具有巨大潜力。然而，在实现高效有机发光二极管 （OLED） 和探索基于这些 ORTP 分子的内部物理机制方面，它仍然充满挑战。在这里，展示了由 ORTP 分子和中间层之间意外的界面自旋混合过程诱导的高性能 OLED，并通过磁-电致发光 （MEL） 和磁-光致发光 （MPL） 测量研究了高效电致发光 （EL） 机制。稳态和瞬态 PL 特性意味着界面效应与 ORTP 分子本身的高位单线态裂变 （HLSF） 过程有关。此外，HLSF 过程和相应的能级位置由入射波长和温度依赖的 PL 光谱和磁场依赖的瞬态 PL 确认。最后，通过优化与发射层相邻的界面材料以利用这种界面自旋混合效应，开发了一种外部量子效率为 16% 且 CIE 坐标为 （0.27， 0.49） 的高效非掺杂 ORTP-OLED。在 EL 过程中提出的机制将为未来基于 ORTP 材料生产更高效的 OLED 提供见解。