Electroluminescence Stability of Organic Light-Emitting Devices Utilizing a Nondoped Pt-Based Emission Layer

摘要

We study the effects of using an emitting material (Pt(II) bis(3-(trifluoromethyl)-5-(2-pyridyl)pyrazolate—Pt(fppz)_(2)) characterized by a preferred horizontal dipole alignment and a nearly unitary quantum yield regardless of concentration on the lifetime of organic light-emitting devices (OLEDs). Using such a material as a dopant in increasingly higher concentrations is found to lead to an increase in device stability, a trend that is different from that commonly observed with conventional OLED guests. The results are consistent with the newly discovered exciton–polaron-induced aggregation degradation mechanism of OLED materials. When this emitter is used as a neat emission layer, the material is already in a highly aggregated state, and the device is no longer affected by exciton–polaron interactions. The results demonstrate the potential stability benefits of using such materials in OLEDs.