Trifunctional Single‐Crystalline Layer for Efficient, Stable, and Simplified White Organic Light‐Emitting Diodes

ABSTRACT Despite their significant potential in advanced display and lighting applications, the commercialization of white organic light‐emitting diodes (WOLEDs) is still hindered by the intrinsic complexity of their multi‐layer device structures and material systems. Here, we demonstrate an all‐in‐one single‐crystalline layer, simultaneously serving as the emissive layer (EML), hole‐transport layer (HTL), and moisture barrier layer (MBL), can effectively overcome these limitations. TBU‐DNA single crystals (SCs) inherently possess strong blue fluorescence emission of an EML, high hole mobility of an HTL, and robust moisture permeation barrier ability of an MBL. By harnessing these triple synergistic functions, we fabricate a three‐organic‐layer WOLED that achieves a maximum current efficiency of 22.1 cd A −1 and EQE of 7.6%. These features represent the highest reported values for WOLEDs fabricated from organic single‐crystalline materials. The inherent barrier property of the TBU‐DNA SCs endows the device with remarkable operational stability, achieving a lifetime (LT 80 ) of 649 h at an initial luminance of 1000 cd m −2 . Through a precise manipulation of the exciton recombination zone, the single‐crystal WOLEDs exhibit a high CRI of 86 and a color temperature of 5580 K. The multifunctional TBU‐DNA single crystals represent a significant advance toward structurally simplified, high‐performance white OLEDs for practical applications.