High-Efficiency Solution-Processed Organic Light-Emitting Diodes with Tetradentate Platinum(II) Emitters

Abstract

The realization of high-efficiency solution-processed organic light-emitting diodes (OLEDs) using phosphorescent tetradentate Pt­(II) emitters and bipolar organic hosts is demonstrated in this work. To investigate the effect of organic host on the platinum dopant, the performances of solution-processed Pt-OLEDs with various combinations between four tetradentate Pt­(II) emitters, including two newly developed tetra-Pt-S2 and tetra-Pt-S3 and three bipolar organic hosts m-TPAPy, o-TPAPy, and o-CzPy, have been analyzed and compared. Among the tetradentate Pt­(II) complexes studied in this work, tetra-Pt-S3 exhibited the best electroluminescent performance attributable to its bulky molecular scaffold structure, high emission quantum yield, and good solubility in common organic solvents. High external quantum efficiencies (EQEs) of up to 22.4% were achieved in the solution-processed OLED with tetra-Pt-S3 emitter and m-TPAPy host at the dopant concentration of 4 wt %. At a high luminance of 1000 cd m–2, the EQE of this device decreased slightly to 21.0%.

P∩N Bridged Cu(I) Dimers Featuring Both TADF and Phosphorescence. From Overview towards Detailed Case Study of the Excited Singlet and Triplet States

“…Essentially, there are two different mechanisms that are already used for harvesting 100% of the excitons, namely the triplet harvesting mechanism [ 2 , 3 , 4 , 5 , 6 ] and the singlet harvesting mechanism [ 7 , 8 , 9 , 10 , 11 , 12 ]. For light generation based on the triplet harvesting mechanism, brightly and fast phosphorescent emitting compounds are required, such as Ir(III) or Pt(II) complexes [ 2 , 3 , 4 , 5 , 6 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. While for singlet harvesting, the molecules have to show efficient thermally activated delayed fluorescence (TADF) at ambient temperature.…”

Theoretical investigation on orange-emitting cyclometalated platinum (II) complexes containing organosilyl/organocarbon-substituted 2-(2-thienyl)pyridine ligands

“…Cyclometalated platinum (II) complexes have been extensively studied in the past two decades for use in different domain and application e.g. photoredox catalytic reaction, bioimaging, sensors and as emitters for organic light emitting diodes (OLEDs) [1][2][3][4][5][6][7][8][9]. Platinum (II) and iridium (III) complexes containing 2-phenylpyridyl (ppy) have been widely investigated due to their high luminescence efficiencies and stability [10,11].…”

P^N bridged Cu(I) Dimers Featuring both TADF and Phosphorescence. From Overview Towards Detailed Case Study of the Excited Singlet and Triplet States.

“…Essentially, there are two different mechanisms that are already used for harvesting 100 % of the excitons, namely the triplet harvesting mechanism [2][3][4][5][6] and the singlet harvesting mechanism [ 7 -12 ]. For light generation based on the triplet harvesting mechanism, brightly and fast phosphorescent emitting compounds are required, such as Ir(III) or Pt(II) complexes [2][3][4][5][6][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. While the molecules suited for exciton harvesting in the triplet and singlet states with subsequent light emission via the singlet state, shortly singlet harvesting mechanism, have to show efficient and fast thermally activated delayed fluorescence (TADF) at ambient temperature.…”