Synthesis and luminescent study of diphosphine-Pt-diacetylide complexes for OLED

Abstract

Two novel diphosphine-Pt-diacetylide complexes were synthesized and characterized by 1H NMR, mass spectrometry and elemental analysis. As a diphosphine, 1,8-bis-(diphenylphosphino)naphthalene (dppn) was prepared and chelated to the Pt(II) center, and p-tolylacetylide (4-CCC 6H 4CH 3) or p-fluorophenylacetylide (4-CCC 6H 4F) was then incorporated to Pt(II) as an anion. The photophysical properties of the Pt complexes were investigated with UV–Vis spectroscopy, photoluminescence (PL) spectroscopy and transient PL. MLCT absorptions of (dppn)Pt(4-CCC 6H 4CH 3) 2 ( 1) and (dppn)Pt(4-CCC 6H 4F) 2 ( 2) were observed at 325 and 320 nm, respectively. To investigate emission properties of the films doped with 1 and 2, these Pt complexes were spin-coated with CBP or MCP. The solid films doped with 1 and 2 showed luminescence at 530 and 520 nm, respectively. Energy transfer from MCP to 1 and 2 seemed to be efficient because luminescence of MCP was not observed. The excited state lifetimes of these complexes were 13–17 ns at room temperature and 17 and 84 ns at 20 K, indicating that the prominent luminescence was fluorescence and the intersystem crossing through LS coupling is rather weak.