학술논문
N-heterocyclic Carbene-Based Tetradentate Pt(II) Complexes with Naphthyl Substituent for Blue Phosphorescent OLEDs / 청색 인광 유기 발광 다이오드를 위한 나프틸 치환체를 갖는 N-헤테로고리 카르벤 기반의 네자리 플라티넘 복합체
Document Type
Dissertation/ Thesis
Author
Source
Subject
Language
English
Abstract
The lifetime of the blue phosphorescent OLEDs has been a challenging problem for commercialization because the high energy of hot exciton generated by triplet-triplet annihilation (TTA) and triplet-polaron quenching (TPQ) at high voltage causes the decomposition of chemical bonds. Therefore, we synthesized Pt-NapCzPy and Pt-NapCzBn, which are N-heterocyclic carbene (NHC)-based tetradentate Pt(II) complexes introduced with a naphthalene group with a T1 energy level similar to that of general Pt(II) complexes. A similar T1 energy level may induce internal energy transfer between Pt(II) and naphthalene and distribute excitons to suppress TTA or TPQ. The photophysical, thermal, electrochemical, and electroluminescent properties of both Pt(II) complexes were systematically investigated. The photoluminescence (PL) spectra of Pt-NapCzPy and PtNapCzBn exhibited a blue emission at PLmax 453 nm and 464 nm with a narrow full width at half maximum (FWHM) of 25 and 41 nm in DCM solution, respectively. The Pt(II) blue PHOLEDs with 5 wt% of Pt-NapCzPy/Pt-NapCzBn as dopant with a mixed co-host system of SiCzCz:SiTrzCz2 exhibited maximum external quantum efficiency (EQEmax) of 15.4/14.1%, maximum current efficiency (CEmax) of 24.1/22.9 cd A-1, maximum power efficiency (PEmax) of 30.2/23.9 lm W-1, CIE(x,y) coordinates of (0.139,0.232)/(0.164,0.224), and LT50 of 19.80/10.98 h, respectively.