Efficient near-infrared organic light-emitting diodes with emission from spin doublet excitons

Hwan-Hee Cho; Sebastian Gorgon; Giacomo Londi; Samuele Giannini; Changsoon Cho; Pratyush Ghosh; Claire Tonnelé; David Casanova; Yoann Olivier; Tomi K Baikie; Feng Li; David Beljonne; Neil C Greenham; Richard H Friend; Emrys W Evans

doi:10.1038/s41566-024-01458-3

Efficient near-infrared organic light-emitting diodes with emission from spin doublet excitons

Nat Photonics. 2024;18(9):905-912. doi: 10.1038/s41566-024-01458-3. Epub 2024 Jun 19.

Authors

Hwan-Hee Cho¹, Sebastian Gorgon¹, Giacomo Londi^{2

3}, Samuele Giannini^{4

5}, Changsoon Cho^{1

6

7}, Pratyush Ghosh¹, Claire Tonnelé^{8

9}, David Casanova^{8

9}, Yoann Olivier², Tomi K Baikie¹, Feng Li¹⁰, David Beljonne⁴, Neil C Greenham¹, Richard H Friend¹, Emrys W Evans^{11

12}

Affiliations

¹ Cavendish Laboratory, University of Cambridge, Cambridge, UK.
² Laboratory for Computational Modelling of Functional Materials, Namur Institute of Structured Matter, University of Namur, Namur, Belgium.
³ Present Address: Department of Chemistry and Industrial Chemistry, University of Pisa, Pisa, Italy.
⁴ Laboratory for Chemistry of Novel Materials, University of Mons, Mons, Belgium.
⁵ Present Address: Institute of Chemistry of OrganoMetallic Compounds, National Research Council (ICCOM-CNR), Pisa, Italy.
⁶ Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea.
⁷ Institute for Convergence Research and Education in Advanced Technology, Yonsei University, Seoul, Republic of Korea.
⁸ Donostia International Physics Centre, Donostia, Spain.
⁹ Ikerbasque Foundation for Science, Bilbao, Spain.
¹⁰ State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, China.
¹¹ Department of Chemistry, Swansea University, Swansea, UK.
¹² Centre for Integrative Semiconductor Materials, Swansea University, Swansea, UK.

Abstract

The development of luminescent organic radicals has resulted in materials with excellent optical properties for near-infrared emission. Applications of light generation in this range span from bioimaging to surveillance. Although the unpaired electron arrangements of radicals enable efficient radiative transitions within the doublet-spin manifold in organic light-emitting diodes, their performance is limited by non-radiative pathways introduced in electroluminescence. Here we present a host-guest design for organic light-emitting diodes that exploits energy transfer with up to 9.6% external quantum efficiency for 800 nm emission. The tris(2,4,6-trichlorophenyl)methyl-triphenyl-amine radical guest is energy-matched to the triplet state in a charge-transporting anthracene-derivative host. We show from optical spectroscopy and quantum-chemical modelling that reversible host-guest triplet-doublet energy transfer allows efficient harvesting of host triplet excitons.

Keywords: Organic LEDs; Photochemistry.