Solution-processed white organic light-emitting diodes with bi-component emitting layer based on symmetry blue spiro-sulfone derivative.

We report a white organic light-emitting diode (WOLED) of simple construction with a bi-component emitting layer, in which a novel, dual-role deep blue TADF emitter as both the non-doped blue emitter and efficient host of an orange TADF emitter of TXO-TPA. The deep blue molecule (SDPS-4PhCz, CIE y ∼ 0.04) was designed using spiro-diphenylsulfone (SDPS) as electron-accepting group and four 9-phenyl-9H-carbazole (N-PhCz) as the electron-donating groups. SDPS-4PhCz showed delayed fluorescence with short delayed lifetime of 1.4 μs via fast reverse intersystem crossing (RISC) from "hot exciton" triplet excited state. The solution-processed, non-doped deep blue inverted OLED device exhibited a maximum EQE of 4.92% with low efficiency roll-off. The two-color WOLED with extremely simple device architecture showed an EQE above 17%, CIE (0.39, 0.44) and high CRI of 64 by spin-coating method. Image 1 • A new deep blue emitter via a spiro concept was designed. • The non-doped deep blue OLED showed a low efficiency roll-off. • The fast RISC process in SDPS-4PhCz coincided with "hot exciton" mechanism. • The two-color WOLED showed an EQE above 17% by spin-coating method. [ABSTRACT FROM AUTHOR]