White organic light-emitting diodes (WOLEDs) with ultra-thin emitting layers have shown considerable potential in solid-state lighting fields due to the simplified structures. However, such WOLEDs with high efficiency, high color rendering index (CRI) and stable spectral emission are still facing challenges. In this paper, we demonstrated a high efficiency and high CRI phosphorescent WOLED by strategically adjusting the positions of red, green and blue phosphorescent ultra-thin layers in exciplex emitter. By investigating the processes of energy transfer and utilization of triplet excitons, a high efficiency, high CRI and stable spectrum emission warm WOLED was successfully fabricated. The maximum external quantum efficiency (EQE), power efficiency (PE) and current efficiency (CE) reached 26.1%, 50 lm W⁻¹,and 40 cd A⁻¹, respectively, and the CRI was as high as 80 in the luminance range from 1000 cd m⁻² to 30000 cd m⁻² with stable emission spectra, exhibiting superior comprehensive EL performances. This work also indicates the potential of undoped ultra-thin layer structures to fabricate high performance WOLEDs for lighting applications.

由于结构简化，具有超薄发光层的白色有机发光二极管（WOLED）在固态照明领域已显示出巨大潜力。然而，具有高效率，高显色指数（CRI）和稳定的光谱发射的这种WOLED仍面临挑战。在本文中，我们通过策略性地调整了激基复合体发射极中的红色，绿色和蓝色磷光超薄层的位置，展示了一种高效，高CRI的磷光WOLED。通过研究三重态激子的能量转移和利用过程，成功制备了高效率，高CRI和稳定光谱发射的WOLED。最大外部量子效率（EQE），功率效率（PE）和电流效率（CE）达到26.1％，50 lm W ^-1在1000 cd m ^-2至30000 cd m ^-2的亮度范围内，具有稳定的发射光谱，CRI分别高达40 cd A ^-1和CRI高达80 ，具有出色的综合EL性能。这项工作还表明了未掺杂的超薄层结构在制造用于照明应用的高性能WOLED方面的潜力。