Improved performance of the thermally activated delayed fluorescence-based cool-white OLEDs with an efficient blue exciplex structure

In this paper, a cool-white OLEDs is proposed with the structure as ITO/TAPC(30 nm)/mCP:Ir(piq)₃ (15 wt%,5 nm)/mCP(5 nm)/mCP:4CzIPN (3 wt%,5 nm)/PO-T2T(40 nm)/LiF(1 nm)/Al(100 nm). The blue emission from Exciplex, combined with red and green guest materials, serves as the basis for the three-primary-color WOLED. Subsequently, the optimization of the device was carried out through single-carrier balance, structural adjustments, tuning of guest doping concentrations, and modifications of the transport layer thickness. As a result, the final WOLEDs achieved a maximum current efficiency (CE_max) of 34.4 cd/A, a maximum power efficiency (PE_max) of 36.1 lm/W, a maximum external quantum efficiency (EQE_max) of 20.8 %, and a color rendering index (CRI) of 81.