Pt(II) Phosphors Featuring Both Dicarbene and Functional Biazolate Chelates: Synthesis, Luminescent Properties, and Applications in Organic Light-Emitting Diodes.
Pt(II) metal complexes [Pt(C^C)(X^X)] comprising three functional dianionic azolate chelates (X^XH2: bipzH2 = 5,5'-di(trifluoromethyl)-3,3'-bipyrazole, bitzH2 = 5,5'-di(trifluoromethyl)-3,3'-bi-1,2,4-triazole, and phpzH2 = 3-(trifluoromethyl)-5-(4-(trifluoromethyl)phenyl)-1H-pyrazole), together with three different charge-neutral dicarbene chelates (i.e., C^C = 1,1'-methylene bis(3-methyl-imidazol-2-ylidene), 1,1'-methylene bis(3-isopropyl-imidazol-2-ylidene), and 1,1'-(propane-1,3-diyl) bis(3-isopropyl-imidazol-2-ylidene), were synthesized and found to show bright solid-state emission depending on the associated X^X and C^C chelates. Pt(II) complexes 1a, 2, and 6 were examined by X-ray diffraction studies, confirming the square-planar skeleton. These Pt(II) metal complexes are found to be nonemissive in degassed solution at RT. The photophysical measurements as neat powder reveals emission maxima ranging from purple to sky blue emission and with high quantum yields for the majority of them. (Time-dependent) density functional theory (DFT/TD-DFT) calculations were executed to elucidate the emission process that was predominated by the combined3LLCT/(3)LMCT/(3)IL character, where LLCT and LMCT and IL stand for ligand-to-ligand charge transfer, ligand-to-metal charge transfer, and intraligand ππ* transition processes. Organic light-emitting devices comprising complex 5a achieved high efficiency (8.9%, 19.4 cd·A(-1), 22.5 lm·W(-1)) with a sky blue emission showing CIEx,y coordinates of (0.18, 0.32).
Department of Chemistry and Low Carbon Energy Research Center, National Tsing Hua University , Hsinchu 30013, Taiwan.
Jia-Ling
JL
Liao
Department of Chemistry and Low Carbon Energy Research Center, National Tsing Hua University , Hsinchu 30013, Taiwan.
Yun
Y
Chi
Fujian Institute of Research on the Structure of Matter, CAS , State Key Laboratory of Structural Chemistry, Fuzhou, 350002, China.
Jin-Yun
JY
Wang
Fujian Institute of Research on the Structure of Matter, CAS , State Key Laboratory of Structural Chemistry, Fuzhou, 350002, China.
Zhong-Ning
ZN
Chen
Institute of Optoelectronic Sciences, National Taiwan Ocean University , Keelung 202, Taiwan.
Zheng-Hua
ZH
Tsai
Institute of Optoelectronic Sciences, National Taiwan Ocean University , Keelung 202, Taiwan.
Wen-Yi
WY
Hung
Material and Chemical Research Laboratories, Industrial Technology Research Institute , Hsinchu 31040, Taiwan.
Meu-Rurng
MR
Tseng
Instrumentation Center, National Taiwan University , Taipei 10617, Taiwan.
Gene-Hsiang
GH
Lee