A sensitization strategy for highly efficient blue fluorescent organic light-emitting diodes

Abstract

Highly efficient blue fluorescent materials have recently attracted great interest for organic light-emitting diode (OLED) application. Here, two new pyrene based organic molecules consisting of a highly rigid skeleton, namely SPy and DPy, are developed. These two blue light emitters exhibit excellent thermal stability. The experiment reveals that the full-width at half-maximum (FWHM) of the emission spectrum can be tuned by introducing different amounts of 9,9-diphenyl-N-phenyl-9H-fluoren-2-amine on pyrene units. The FWHM of the emission spectrum is only 37 nm in diluted toluene solution for DPy. Furthermore, highly efficient blue OLEDs are obtained by thermally activated delayed fluorescence (TADF) sensitization strategy. The blue fluorescent OLEDs utilizing DPy as emitters achieve a maximum external quantum efficiency (EQE) of 10.4% with the electroluminescence (EL) peak/FWHM of 480 nm/49 nm. Particularly, the EQE of DPy-based device is boosted from 2.6% in non-doped device to 10.4% in DMAc-DPS TADF sensitized fluorescence (TSF) device, which is a 400% enhancement. Therefore, this work demonstrates that the TSF strategy is promising for highly efficient fluorescent OLEDs application in wide-color-gamut display field. Graphical Abstract

Forthcoming hyperfluorescence display technology: relevant factors to achieve high-performance stable organic light emitting diodes

“…Spectral overlapping refers to the degree of overlap between the absorption spectra of the fluorescent emitter and the emission spectra of the assistant host (charge transport materials) ( Bennett, 2004 ; Duan et al, 2022 ). When the emission spectrum of the assistant host, usually TSH, overlaps with the absorption spectrum of the final fluorescent dopant, some of the energy from the emitter is absorbed, and thus more efficient energy transfer can be anticipated ( Nakanotani et al, 2014 ; Cravcenco et al, 2020 ).…”