| Abstrakt: |
The ionic transition metal complexes (iTMCs) [{Pt(C∧C*)(μ-Rpz)}2Ag(PPh3)]X (HC∧C* = 1-(4-(ethoxycarbonyl)phenyl)-3-methyl-1H-imidazole-2-ylidene, X = ClO4/PF6;Rpz = pz 1a/2a, 4-Mepz 1b/2b, and 3,5-dppz 1c/2c) were prepared from the neutral [{Pt(C∧C*)(μ-Rpz)}2] (Rpz = pz A, 4-Mepz B, and 3,5-dppz C) and fully characterized. The “Ag(PPh3)” fragment is in between the two square-planar platinum units in an “open book” disposition and bonded through two Pt–Ag donor–acceptor bonds, as shown by X-ray diffraction (dPt–Ag∼ 2.78 Å, 1a–1c). 195Pt{1H} and 31P{1H} NMR confirmed that these solid-state structures remain in solution. Photoluminescence studies and theoretical calculations on 1a, were performed. The diphenylpyrazolate derivatives show the highest photoluminescence quantum yield (PLQY) in the solid state. Therefore, 2cand its neutral precursor Cwere selected as active materials on light-emitting devices. OLEDs fabricated with Cshowed a turn-on voltage of 3.2 V, a luminance peak of 21,357 cd m–2at 13 V, and a peak current efficiency of 28.8 cd A–1(9.5% EQE). They showed a lifetime t50of 15.7 h. OLEDs using 2cshowed a maximum luminance of 114 cd m–2, while LECs exhibited a maximum luminance of 20 cd m–2and a current efficiency of around 0.2 cd A–1, with a t50value of 50 min. |
