Illustration from Scientific Research

Under the thermal equilibrium (described by the black arrows), reduced V nr can be realized by exploiting the thermal population of the more emissive states related with the guest component, where the luminescent efficiencies of different states are represented by the thickness of the coloured arrows. From the perspective of the device performance, the guest binary device should have higher EQE EL than the host binary device (that is, EQE EL G > EQE EL H). In addition, to fully make use of the CT G and LE G without sacrificing the VOC rad, the CT G energy should be close to the CT H energy (that is, {E}_{{CT}_{H}}{E}_{{CT}_{G}}).

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