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

Luca M Cavinato; Sarah Wölfl; Alexander Pöthig; Elisa Fresta; Claudio Garino; Julio Fernandez-Cestau; Claudia Barolo; Rubén D Costa

doi:10.1002/adma.202109228

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

Adv Mater. 2022 Mar;34(12):e2109228. doi: 10.1002/adma.202109228. Epub 2022 Feb 12.

Authors

Luca M Cavinato¹, Sarah Wölfl¹, Alexander Pöthig², Elisa Fresta¹, Claudio Garino^{3

4}, Julio Fernandez-Cestau¹, Claudia Barolo^{3

4

5}, Rubén D Costa¹

Affiliations

¹ Chair of Biogenic Functional Materials, Technical University of Munich, Schulgasse 22, 94315, Straubing, Germany.
² Department of Chemistry & Catalysis Research Center (CRC), Technical University of Munich, Lichtenbergstr. 4, 85747, Garching, Germany.
³ Department of Chemistry, University of Turin, Via Giuria 7, Turin, 10125, Italy.
⁴ NIS Interdepartmental Centre and INSTM Reference Centre, University of Turin, Via Gioacchino Quarello 15/a, Turin, 10125, Italy.
⁵ ICxT Interdepartmental Centre, University of Turin, Lungo Dora Siena 100, Turin, 10153, Italy.

PMID: 35034407
DOI: 10.1002/adma.202109228

Abstract

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: λ = 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.

Keywords: blue emitters; copper(I) complexes; light-emitting electrochemical cells; multivariate design experiment; white lighting sources.

Abstract

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