Highly efficient hybrid warm white organic light-emitting diodes using a blue thermally activated delayed fluorescence emitter: exploiting the external heavy-atom effect

摘要

Warm white organic light-emitting diodes with a power efficiency of up to 85.3 lm W–1 are reported by scientists in China. The emitters fabricated by Dongdong Zhang and co-workers from Tsinghua University in Beijing are based on the use of a yellow phosphor (PO-01) and a blue fluorophore (2CzPN), which exhibits thermally activated delayed fluorescence (TADF). The device operates with a total external quantum efficiency of 33.3%. The team says that such high efficiency is made possible by the minimizing the fluorescence quenching processes that can occur between the phosphor and the fluorophore. In particular, their TADF fluorophore is shown to be highly robust against quenching resulting from external heavy atom effects introduced by metal phosphors. The approach could lead to a simpler design of white emitters.