White Light-Emitting Electrochemical Cells Based on Deep-Red Cu(I) Complexes

The synthesis and characterization, as well as photoluminescent and electrochemical features of a series of ionic copper(I) complexes—, i.e., [Cu(N^{^}N)(P^{^}P)]⁺, where N^{^}N is 4,4′-diethylester-2,2′-biquinoline (dcbq) and P^{^}P is bis-triphenylphosphine, bis[2-(diphenylphosphino)phenyl)ether] (POP), or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos)—are reported along with their application to achieve both deep-red and white light-emitting electrochemical cells (LECs). In short, the first deep-red Cu(I)-based LECs featuring high irradiances (≈100 µW cm⁻²) and excellent color stability (x/y CIE color coordinates of 0.66/0.32) over days are reported. This is achieved by comparing the electroluminescent behavior of this series of complexes with respect to the irradiance and stability, as well as the impact of introducing supporting electrolytes on the device performance. This is rationalized using spectroscopic and electrochemical studies. Finally, the first white-emitting LEC is manufactured with red-emitting copper(I) complexes, achieving x/y CIE color coordinates of 0.31/0.32 and a high color rendering index of 92.