Achievement of High-Level Reverse Intersystem Crossing in Rubrene-Doped Organic Light-Emitting Diodes

• DOI: 10.1021/acs.jpclett.0c00451
• Publication Date: 2020-03-19T19:22:42Z
• Authors: Xiantong Tang; Ruiheng Pan; Xi Zhao; Hongqiang Zhu; Zuhong Xiong
• Keywords: Rubrene; Intersystem crossing

Using the fingerprint magneto-electroluminescence trace, we observe a fascinating high-level reverse intersystem crossing (HL-RISC) in rubrene-doped organic light-emitting diodes (OLEDs). This HL-RISC is achieved from high-lying triplet states (T2,rub) transferred host by Dexter energy transfer to lowest singlet (S1,rub) rubrene. Although decreases with bias current, it increases lowering temperature. contrary temperature-dependent RISC conventional thermally activated delayed fluorescence, because an exothermic process instead. Moreover, owing competition of exciton direct charge trap, changes nonmonotonically dopant concentration and luminous efficiency maximum at 10% rubrene, which about ten times greater than that pure-rubrene device. Additionally, not observed bare films absence T2,rub. Our findings pave way for designing highly efficient orange fluorescent OLEDs.