Researchers from Korea's KAIST research institute developed a high-efficiency OLED architecture that uses external scattering medium to achieve an EQE greater than 50%.
Such high EQE was only demonstrated before using complex internal nanostructures or by employing a micro-lens array, but these solutions are complicated to produce and can hinder the OLEDs flexibility and planar structure. The researchers say that their scattering approach maintains the planar geometry , results in flexible OLEDs and can be easily scaled to enable low cost production.
This is not the first research that focuses on light scattering, but this time the KAIST ream developed comprehensive and analytical methodology to theoretically predict structures that maximize efficiency, and then followed with producing prototypes that feature an optimal light scattering film (made from SiO2). The orange-emitting prototype realized an EQE of 56% and a power efficiency of 221 lm/W.