Preparation and electroluminescent application of iridium(III) complexes containing sulfur-containing phenylpyridazine l

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Preparation and electroluminescent application of iridium(III) complexes containing sulfur‑containing phenylpyridazine ligands Wei Cheng1 · Ren Sheng2 · Yan Wang1 · Yuting Liu1 · Bihai Tong1   · Ping Chen2 · Song Wang3 Received: 9 August 2020 / Accepted: 2 September 2020 © Springer Nature Switzerland AG 2020

Abstract Four iridium(III) complexes (1–4) with sulfur-containing phenylpyridazine ligands were successfully synthesized and characterized. The structure of complex 3 was further confirmed by single X-ray structural analysis. These complexes showed strong green phosphorescence at room temperature with peak wavelengths ranging from 524 to 539 nm in C ­ H2Cl2 solution. These complexes exhibited medium quantum yields of 42 ~ 61% in PMMA films with lifetimes of 1.58 ~ 3.26 μs. These complexes also exhibited good thermal stability with Td > 275 °C. The phosphorescent OLEDs were fabricated using complexes 1 and 2 as dopants. The device using complex 2 displayed good performances with the maximum luminance, current efficiency, power efficiency and external quantum efficiency of 8913 cd m−2, 44.2 cd A−1, 30.7 lm W−1 and 11.8%, respectively. These results indicate excellent application prospects of these iridium(III) complexes as efficient phosphors in OLEDs. Keywords  Cyclometalated iridium(III) complex · Phenylpyridazine · Sulfur · OLEDs

Introduction

Wei Cheng, Ren Sheng and Yan Wang have contributed equally to this work Electronic supplementary material  The online version of this article (https​://doi.org/10.1007/s1124​3-020-00424​-6) contains supplementary material, which is available to authorized users. * Bihai Tong [email protected] * Ping Chen [email protected] * Song Wang [email protected] 1



Key Laboratory of Metallurgical Emission Reduction and Resources Recycling, Ministry of Education, Institute of Molecular Engineering and Applied Chemistry, School of Metallurgy Engineering, Anhui University of Technology, Maanshan 243002, Anhui, China

2



State Key Laboratory On Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, P. R. China

3

Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices, Hubei University of Arts and Science, Xiangyang 441053, China



In the past 20 years, organic light-emitting diodes (OLEDs) have drawn increasing attention because of their potential applications in flat-panel displays and solid-state lighting [1]. Among various electroluminescent materials, luminescent iridium(III) complexes are the most widely investigated materials for highly efficient OLEDs. These complexes exhibited high quantum yields, facile color tenability and strong thermal stability [2–4]. Phenylpyridazine-based iridium(III) complexes have unique properties, such as easy preparation and excellent stability [5–7]. The OLEDs comprising them also showed excellent device performance. For example, Mi et al. [8] reported that complex Ir(BPPa)3 has a Td (the 5% weight loss temperature) of as high as 426 °C, and the OLEDs base