Doping Modulated Solution Processed Single Molecule Fluorescence-Phosphorescence Dual Emission Pure White Organic Light Emitting Diodes

Abstract

In conventional studies, doping single molecule fluorescence-phosphorescence dual-emission materials with small molecule hosts to achieve white light emission suffers from several limitations, the exciton dynamic coupling mechanism remains unclear, limited solution processability, and low device efficiency. These challenges have significantly hindered both the theoretical exploration and practical application of single molecule room temperature fluorescence-phosphorescence dual emission materials. In this work, F XyIBA-Cz was employed as the guest emitter and SimCP2 as the small molecule host to investigate exciton dynamic coupling. Analysis of intersystem crossing (ISC) rates and radiative transitions before and after doping revealed that the host effectively suppressed intermolecular interactions and charge transfer between guest molecules. This modulation, coupled with the tunable dual emission behavior of F XyIBA-Cz, enabled electroluminescence ranging from yellow-green to pure white. In OLED devices, compared with the SimCP2-based doped device (EQE: 0.42%), the PVK-based doped device achieved low cost, high efficiency pure white emission (CIE: 0.30, 0.33; EQE: 1.90%). Studies of exciton dynamics, trap density, and phase distribution confirmed that PVK more effectively suppressed ISC and trapping effects of F XyIBA-Cz than SimCP2, thereby yielding a higher EQE. This work provides a new strategy for designing efficient, solution-processed WOLEDs based on single-molecule dual-emission systems..