Boron‐Containing Molecules with Fluorescence‐Phosphorescence Dual‐Emission for Mechanochromism and Single Molecular White Light‐Emitting Diodes

Abstract

Organic molecules with fluorescence‐phosphorescence dual‐emission have attracted significant attention for their potential applications in white organic light‐emitting diodes (WOLEDs). Herein, donor–accepter molecules, Mes*BA‐Cz and FXylBA‐Cz, are designed and synthesized, and the photoluminescence of these two compounds in solid state exhibits fluorescence‐phosphorescence dual‐emission. Through the single crystal study, the phosphorescent emission is mainly caused by the molecular stacking in the crystalline state, which is beneficial for aggregation‐induced intersystem crossing. Dual emission behavior further caused the mechanochromism of the two compounds, with emission color changed between amorphous and crystalline state. White light photoluminescence with CIE coordinates of (0.33, 0.34) is achieved by doping FXylBA‐Cz in the poly (methyl methacrylate) film. Furthermore, a WOLED based on FXylBA‐Cz is manufactured with CIE coordinates of (0.31, 0.33), and the external quantum efficiency (EQE) reached 0.49%.

Single-molecule white organic light-emitting diodes based on dual-conformation diindolophenthiazine derivatives

“…External stimuli such as grinding and heating have been shown to alter molecular arrangements, resulting in distinct luminescent properties in the solid state. 23,25,27,50–55 To investigate this phenomenon, we examined the mechanochromic luminescence of the compounds in the solid state, using BP1 as an illustrative example. As depicted in Fig.…”

“…18,19 The focus has shifted towards single molecular white emitters due to their simplicity in manufacturing, reproducibility, and stable emission spectra. 20–27…”

“…Although white photoluminescence (PL) has been described for several molecules under photoexcitation, 21,26,28–34 only a few compounds can exhibit white electroluminescence (EL) under electrical excitation. 24,25,27,35,36…”