A family of pyrene­[4,5-d]­imidazole derivatives, PyPA, PyPPA, PyPPAC, and PyPAC, with different excited states are successfully developed. Among them, PyPPA and PyPPAC possess hybridized local and charge-transfer (HLCT) state, endowing them with pure blue fluorescence as well as high quantum yields. The nondoped organic light-emitting diode (OLED) based on PyPPA displays Commission Internationale de L’Eclairage coordinates of (0.14, 0.13) and achieves a maximum external quantum efficiency (EQE) of 8.47%, which are among the highest value reported to date for nondoped blue HLCT OLEDs. The nondoped OLED based on PyPPAC exhibits a maximum luminance of 50,046 cd m–2 located in the blue region with CIE coordinates of (0.15, 0.21) and an EQE of 6.74% even when the luminance reached over 10,000 cd m–2. In addition, they both reveal ultimate exciton utilizing efficiencies of nearly 100%. The potential of a blue emitter of PyPPA with an HLCT character for application in white OLED (WOLED) is further tested. The efficient two-color hybrid warm WOLED is successfully achieved, which provides the total EQE, power efficiency, and current efficiency of up to 21.19%, 61.46 lm W–1, and 62.13 cd A–1, respectively. The nondoped blue OLEDs and hybrid WOLEDs present good color stabilities with low efficiency roll-offs. Our results prove that taking advantage of the HLCT state, nondoped blue OLEDs as well as hybrid WOLEDs with high performance could be realized, which have a promising prospect for the displays and lightings in the future.

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PIBz-3-PTZ exhibits strong fluorescence with a photoluminescence quantum yield of 35% in films. The nondoped device achieves a maximum external quantum efficiency of 2.02% peaking at 672 nm with small efficiency roll-off.

Achieving high external quantum efficiency (EQE) for non-doped deep blue fluorescent organic light-emitting diodes (OLEDs) with Commission international de I'Eclairage (CIE) coordinate of CIEy < 0.08 remains a big challenge....

The development of efficient thermally activated delayed fluorescence (TADF) materials with a deep-red emission (emission wavelength beyond 620 nm) remains a great challenge in the field of organic light-emitting diodes...

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