Precise Regulation of Emissive Layer for Ultra-High Performance White Organic Light-Emitting Diodes in Exciplex Forming Co-host System $(document).ready(function() { if (!$("html").hasClass("ie8")) { $.ajax({ url: "https://crossmark-cdn.crossref.org/widget/v2.0/widget.js", dataType: "script", cache: true }).done(function() { $(".crossmark-button").addClass("visible"); }); } });

Abstract

Nowadays, white organic light-emitting diodes (WOLEDs) have attracted more attention in solid-state lighting due to its merits of low power consumption, flat shadowless illumination, soft and weak blue light and flexible emission and so on. Regrettably, it is still an extremely challenging subject to achieve ultra-efficient WOLEDs exceeding 100 lm W−1. In this paper, we presented a general approach to achieve low turn-on voltage (~ 2.4 V), ultra-high efficiency WOLEDs based on exciplex forming co-host system. The key to our design strategy is the precise management of phosphor dopant concentration and reasonable arrangement of emissive layers to efficiently solve the trade-off between charge carrier trapping and energy transfer in electroluminescence (EL) processes. The resulting WOLEDs realize the forward-viewing maximum power efficiency and external quantum efficiency of 106.4 lm W−1 and 23.5%, 69.9 lm W−1 and 23.4%, respectively, for complementary-color and three-color WOLEDs. The EQEs remain over 22% at 1000 cd m−2, exhibiting extremely low efficiency roll-off. Such outstanding device performance and ultra-high efficiencies should be contributed to the enhancement of energy transfer and the reduction of charge carrier trapping in exciplex co-host system. The findings will be conducive to enhancing the efficiency of WOLEDs, and promoting the industrial development in lighting markets.