Single-component exciplex hosts for OLED application

Abstract

Fluorescent organic light-emitting diode (FOLED) using double-component intermolecular exciplex, i.e., the physical blend of an electron donor (D) and an electron acceptor (A), as host material will suffer from very precise and delicate control on the doping procedure. Herein, we demonstrate that the replacement of double-component intermolecular exciplex host with its single-component counterpart can not only result in simplified device fabrication processes, but also lead to significantly enhanced electroluminescence (EL) performance. The reason is that mono-component exciplex could trigger more effective intermolecular D/A interactions, and hence higher exciton utilization efficiency (ηr: 50% vs. 16%) as well as better film amorphism and thermal stability than its bi-component counterpart. Furthermore, by taking advantage of the efficient TTA process occurring on the pyrene constructive units, a single-component exciplex-hosted FOLED capable of showing quite stable and relatively high ηr in a rather large driving current density range is realized (54%–63%@0.1–550 mA cm−2). This work not only deciphers the superiority of single-component intermolecular exciplexes over their double-component counterparts in FOLED host applications, but also sheds light on the rational design of host materials for acquiring FOLEDs with stable and high ηrs under various current densities.