Multivariate Analysis Identifying Cu(N∧N)(P∧P)~+ Design and Device Architecture Enables First-Class Blue and White Light-Emitting Electrochemical Cells

摘要

White light-emitting electrochemical cells (LECs) comprising only Cu(N^N)(P^P)(+) have not been reported yet, as all the attempts toward blue-emitting complexes failed. Multivariate analysis, based on prior-art Cu(N^N)(P^P)(+)-based thin-film lighting (90 papers) and refined with computational calculations, identifies the best blue-emitting Cu(N^N)(P^P)(+) design for LECs, that is, N^N: 2-(4-(tert-butyl)phenyl)-6-(3,5-dimethyl-1H-pyrazol-1-yl)pyridine and P^P: 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, to achieve predicted thin-film emission at 490 nm and device performance of 3.8 cd A(-1)@170 cd m(-2). Validation comes from synthesis, X-ray structure, thin-film spectroscopic/microscopy/electrochemical characterization, and device optimization, realizing the first Cu(N^N)(P^P)(+)-based blue-LEC with 3.6 cd A(-1)@180 cd m(-2). This represents a record performance compared to the state-of-the-art tricoordinate Cu(I)-complexes blue-LECs (0.17 cd A(-1)@20 cd m(-2)). Versatility is confirmed with the synthesis of the analogous complex with 2-(4-(tert-butyl)phenyl)-6-(3,5-dimethyl-1H-pyrazol-1-yl)pyrazine (N^N), showing a close prediction/experiment match: lambda = 590/580 nm; efficiency = 0.55/0.60 cd A(-1)@30 cd m(-2). Finally, experimental design is applied to fabricate the best white multicomponent host:guest LEC, reducing the number of trial-error attempts toward the first white all-Cu(N^N)(P^P)(+)-LECs with 0.6 cd A(-1)@30 cd m(-2). This corresponds to approximately ten-fold enhancement compared to previous LECs (0.05 cd A(-1)@12 cd m(-2)). Hence, this work sets in the first multivariate approach to design emitters/active layers, accomplishing first-class Cu(N^N)(P^P)(+)-based blue/white LECs that were previously elusive.