Achieving High-Performance Solution-Processed Orange OLEDs with the Phosphorescent Cyclometalated Trinuclear Pt(II) Complex

Abstract

Cyclometalated Pt(II) complexes can show intense phosphorescence at room temperature. Their emission properties are determined by both the organic ligand and the metal center. Whereas most of the related studies focus on tuning the properties by designing different types of organic ligands, only several reports investigate the key role played by the metal center. To address this issue, phosphorescent Pt(II) complexes with one, two, and three Pt(II) centers are designed and synthesized. With more Pt(II) centers, the cyclometalated multinuclear Pt(II) complexes display red-shifted emissions with increased photoluminescence quantum yields. Most importantly, solution-processed organic light-emitting diodes (OLEDs) with the conventional device structure using the multinuclear Pt(II) complexes as emitters show excellent performance. The controlled device based on the conventional mononuclear Pt(II) complex shows a peak external quantum efficiency, current efficiency, and power efficiency of 6.4%, 14.4 cd A, and 12.1 lm W, respectively. The efficiencies are dramatically improved to 10.5%, 21.4 cd A, and 12.9 lm W for the OLED based on the dinuclear Pt(II) complex and to 17.0%, 35.4 cd A, and 27.2 lm W for the OLED based on the trinuclear Pt(II) complex, respectively. To the best of our knowledge, these efficiencies are among the highest ever reported for the multinuclear Pt(II) complex-based OLEDs.

Dinuclear Design of a Pt(II) Complex Affording Highly Efficient Red Emission: Photophysical Properties and Application in Solution-Processible OLEDs

“…72 Amongst Pt(II)-based devices, on the other hand, vacuumdeposited OLEDs have recently reached an EQE of around 20% in the red / NIR, 73 but, for a solutionprocessed deep-red-emitting Pt(II)-based device, the EQE of almost 10% obtained here renders it amongst the highest reported. 74,75,76…”

An efficient heterodinuclear Ir(iii)/Pt(ii) complex: synthesis, photophysics and application in light-emitting electrochemical cells

“…With such rich design properties at hand, it is not surprising that multinuclear complexes are gaining popularity as the emitting species in organic light-emitting diodes (OLEDs), 1, [13][14][15][16][17][18][19][20][21] and also have contributed to an impressive device performance. For instance, Zhou and co-workers report on the successful application of Ir and Pt homodinuclear complexes as the emitter in OLEDs that exhibit a very high efficiency, 13,22 while others have demonstrated well-performing OLED devices based on homodinuclear and heterodinuclear complexes that emit with a broad variety of emission colors at high efficiency. 2 The light-emitting electrochemical cell (LEC) features a number of distinct advantages over the OLED, notably the opportunity to employ a robust single-layer active material and air-stabile electrodes, [23][24][25][26][27][28][29] which in turn render the LEC an ideal candidate for a low-cost 30 and low-energy solution-based [31][32][33][34][35][36] fabrication.…”

Configurationally Stable Platinahelicene Enantiomers for Efficient Circularly Polarized Phosphorescent Organic Light‐Emitting Diodes

“…[11] On the contrary,p hosphorescent materials could harvest both singlet and triplet excitons leading to 100 %i nternalq uantum efficiency,w hich plays an important role in OLEDs. [12] In 2015, our group reported highly efficient circularly polarized phosphorescent OLEDs (CP-PhOLEDs) with j g EL j of 2.6 10 À3 by introducing chiral iridium(III) complexesa st he emitters. [13] Later, Zhao's group also reported CP-PhOLEDs based on chiral Ir III isocyanidec omplexes achieving the j g EL j of 3 10 À3 ,w hichi st he highest valuea mong the reported CP-PhOLEDs based on Ir III complexes.…”