Photophysical properties and stability of binuclear emissive Copper(I) complexes Co-deposited with CuX (X = Cl, Br, I) and aza-9,9′-spirobifluorenes

Abstract

Cuprous complexes are considered as promising alternatives to phosphorescent Ir complexes in the applications of electroluminescent devices in recent years. In addition, the co-deposition route is a common synthesis method using Cu(I) halide and organic materials to generate a Cu(I) complex as an emitter of organic light-emitting diodes (OLEDs). In the research presented here, we investigated the photoluminescence (PL) characteristics of Cu(I) complexes co-deposited by aza-9,9′- spirobifluorene and CuX (X = Cl, Br, I) at different doping concentrations. We found that the CuCl, CuBr, and CuI with a molar ratio respectively at 7%, 7%, and 9% exhibited higher PL quantum yields and external quantum yield, and CuBr as a doping halide showed the best performance. We then systematically investigated the complexes in response to external stimulation (water, oxygen and thermal annealing, operation voltage). The results exhibit obvious phase decomposition with increasing annealing temperature, exposure time, and applied voltage. Finally, we conclude that the co-deposited Cu(I) complexes are vulnerable to external stimulation. Based on this work, employing co-deposited Cu(I) complexes as an emitter is a suitable way to fabricate high-efficiency and stable OLED that merits further research.