Fig. 5: Electroluminescence characterization.
From: Hot exciplexes in U-shaped TADF molecules with emission from locally excited states
a Schematic device structure of the OLEDs. b Transient electroluminescence kymographs revealing the contribution of triplet–triplet annihilation up-conversion (TTA-UC). The black line represents the data; the dashed red line is a fitting curve according to the TTA-UC model. c The estimated radiative production efficiency as a function of the current density showing that ηr estimated by transient electroluminescence (dotted data points) is lower than ηr determined by EQE measurements (solid data points) within the examined interval of current densities. Blue data represent MeFuPAI, black data BeFuPAI. d External quantum efficiencies as a function of current density. The dotted, red lines represent the respective maximal EQEs for conventional fluorescent OLEDs harvesting only singlet excitons.
