Highly Emissive Dinuclear Platinum(III) Complexes

Xiugang Wu; Deng-Gao Chen; Denghui Liu; Shih-Hung Liu; Shin-Wei Shen; Chih-I Wu; Guohua Xie; Jianwei Zhou; Zhi-Xuan Huang; Chun-Ying Huang; Shi-Jian Su; Weiguo Zhu; Pi-Tai Chou

doi:10.1021/jacs.9b13956

Highly Emissive Dinuclear Platinum(III) Complexes

J Am Chem Soc. 2020 Apr 22;142(16):7469-7479. doi: 10.1021/jacs.9b13956. Epub 2020 Apr 7.

Authors

Xiugang Wu¹, Deng-Gao Chen, Denghui Liu¹, Shih-Hung Liu, Shin-Wei Shen, Chih-I Wu, Guohua Xie², Jianwei Zhou¹, Zhi-Xuan Huang, Chun-Ying Huang, Shi-Jian Su³, Weiguo Zhu¹, Pi-Tai Chou

Affiliations

¹ School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Jiangsu Engineering Laboratory of Light-Electricity-Heat Energy-Converting Materials and Applications, Jiangsu Key Laboratories of Environment-Friendly Polymers, National Experimental Demonstration Center for Materials Science and Engineering, Changzhou University, Changzhou 213164, China.
² Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan 430072, China.
³ Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640, China.

PMID: 32223139
DOI: 10.1021/jacs.9b13956

Abstract

Dinuclear Pt(III) complexes were commonly reported to have short-lived lowest-lying triplet states, resulting in extremely weak or no photoluminescence. To overcome this obstacle, a new series of dinuclear Pt(III) complexes, named Pt2a-Pt2c, were strategically designed and synthesized using donor (D)-acceptor (A)-type oxadiazole-thiol chelates as bridging ligands. These dinuclear Pt(III) complexes possess a d⁷-d⁷ electronic configuration and exhibit intense phosphorescence under ambient conditions. Among them, Pt2a exhibits orange phosphorescence maximized at 618 nm in degassed dichloromethane solution (Φ_p ≈ 8.2%, τ_p ≈ 0.10 μs) and near-infrared (NIR) emission at 749 nm (Φ_p ≈ 10.1% τ_p ≈ 0.66 μs) in the crystalline powder and at 704 nm (Φ_p ≈ 33.1%, τ_p ≈ 0.34 μs) in the spin-coated neat film. An emission blue-shifted by more than 3343 cm^-1 is observed under mechanically ground crystalline Pt2a, affirming intermolecular interactions in the solid states. Time-dependent density functional theory (TD-DFT) discloses the lowest-lying electronic transition of Pt2a-Pt2c complexes to be a bridging ligand-metal-metal charge transfer (LMMCT) transition. The long-lived triplet states of these dinuclear platinum(III) complexes may find potential use in lighting. Employing Pt2a as an emitter, high-performance organic light-emitting diodes (OLEDs) were fabricated with NIR emission at 716 nm (η = 5.1%), red emission at 614 nm (η = 8.7%), and white-light emission (η = 11.6%) in nondoped, doped (in mCP), and hybrid (in CzACSF) devices, respectively.