Managed carrier density and distribution in solution-processed emission layer to achieve highly efficient and bright blue organic light-emitting devices

Abstract

In this paper, solution-processed blue organic light-emitting devices (OLEDs) with high efficiency and high luminance are realized. A blue thermally activated delayed fluorescence (TADF) material, 4CzFCN, is used as the emitting material. A host material with high hole mobility, mCP, and an electron transport material with high electron mobility and lower LUMO level, B4PyMPM, are employed to increase the electron density and balance the carrier distribution inside the emission layer. As a result, a luminance of 7625.0 cd/m 2 , a current efficiency of 49.3 cd/A, and an external quantum efficiency of up to 24% are obtained. To the best of our knowledge, these values are superior to the highest values reported for this material in the literatures. • By managing the carrier density and the carrier balance inside the EML, the solution-processed blue OLEDs performance was improved greatly. • The maximum current efficiency of the champion device is 49.3 cd/A, which is the highest efficiency reported from OLEDs with this material. • The high-efficiency device also achieved a high luminance of 7625 cd/m 2 , which is the highest luminance reported from OLEDs with this material.