Although organic light-emitting diodes(OLEDs)have been commercialized and become popular in smartphone,the vacuum deposition process makes them too expensive for mass production and less cost-effective.Herein,we employed highly emissive platinum complex as the sensitizer and multi-resonant thermally activated delayed fluorescence(MR-TADF)molecules as the emitters to demonstrate highly efficient,high color purity,and solution-processed OLEDs with the alleviated efficiency roll-offs.The triplet excitons are rapidly converted to singlet excitons assisted by the phosphorescent sensitizer.Attributed to the reduced triplet exciton lifetime induced by the phosphorescent sensitizer,the MR-TADF OLEDs exhibited a maximum external quantum efficiency(EQE)of 13.2%with a low efficiency roll-off of 25.8%at 1 000 cd/m².To reduce Dexter energy transfer between phosphorescence sensitizer and the emitter,an analogue TADF emitter with the peripheral bulky blocking units was employed,which rendered an improved maximum EQE of 13.6%.This investigation presents a general approach to realize high-performance solution-processed electroluminescence.
维普
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