A novel strategy of “Like–Likes–Like” is proposed to design and synthesize the electron transport materials (ETMs) and emitters for high-performance electroluminescent devices, including similar characteristics of structures, molecular orbitals, and ground/excited-states. Two novel compounds based on this strategy, PI–DPO–TPA and PI–DPO–PI, were successfully synthesized and applied to the fabrication of efficient organic light-emitting diodes (OLEDs). Both compounds cooperate well with each other from the perspective of exciton dynamics when respectively deposited as the non-doped OLED emitter and the ETM layers. Therefore, the devices exhibit an extremely low turn on voltage (2.0 V) and high efficiencies (18.87 cd A−1, 16.91 lm W−1, and 8.45%). In comparison, the control device with traditional ETM layers (i.e. TmPyPB) shows a relatively poor performance (4.5 V, 12.32 cd A−1, 4.02 lm W−1, and 4.20%). Furthermore, electron/hole-only devices, magneto-electroluminescence, and transient absorption spectra determine the contribution from the boosted formation of hot excitons, rather than the simply enhanced transport of a low-lying electron. The findings open a novel avenue to prepare ETMs and emitters for highly-efficient OLEDs.
Efficient and fast scintillators are in high demand in a variety of fields, such as medical diagnostics, scientific instruments and high-energy physics. However, the trade-off between high scintillation efficiency and fast timing properties is a common challenge facing almost all scintillators. To overcome this limitation, we have developed a strategy for organic scintillators by directing all hot excitons into fast singlet emission states without involving the lowest triplet states. Our scintillator, 1,1,2,2-tetrakis(4-bromophenyl)ethylene, shows an ultrafast radiative lifetime of 1.79 ns and a light yield of ∼ 34,600 photons per MeV, exhibiting an excellent combination of high light yield and short decay time. Our work provides a method to design efficient and ultrafast scintillators, and paves the way towards exciting applications for ultrafast detection and imaging.
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