Single-Layer Blue Organic Light-Emitting Diodes With Near-Unity Internal Quantum Efficiency.

Sachnik, Oskar; Li, Yungui; Tan, Xiao; Michels, Jasper J; Blom, Paul W M; Wetzelaer, Gert-Jan A H · Adv Mater · 2023

basic_science · Level V

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Abstract

Efficient organic light-emitting diodes (OLEDs) commonly comprise a multilayer stack including charge-transport and charge- and exciton-blocking layers, to confine charge recombination to the emissive layer. Here, a highly simplified single-layer blue-emitting OLED is demonstrated based on thermally activated delayed fluorescence with the emitting layer simply sandwiched between ohmic contacts consisting of a polymeric conducting anode and a metal cathode. The single-layer OLED exhibits an external quantum efficiency of 27.7% with minor roll-off at high brightness. The internal quantum efficiency approaches unity, demonstrating that highly simplified single-layer OLEDs without confinement layers can achieve state-of-the-art performance, while greatly reducing the complexity of the design, fabrication, and device analysis.