Abstract
Conjugated polymers used in NLO are investigated in this study. Poly(n-vinyl-carbazole) (PVK) and polycarbazole (PCZ) have been used as a host polymer. Two chromophores, 9-Hexyl-3,6-bis-[2-(4- nitro-phenyl)-vinyl]-9H-carbazole (CzPhNO2) and 2- {2,6- Bis- [2- (4- diethylamino-phenyl)-vinyl]-pyran-4-ylidene}-malononitrile (DCDEt), have been prepared and used in four guest/host NLO systems. The d33 value has been improved when PCZ was added. The anchoring effect of CzPhNO2 leads better thermal stability than DCDEt, meanwhile, the plasticizer effect of PCZ leads lower effective transition temperature (T0). UV-Vis spectra show apparent red-shift in each system after casting. Accordingly, π-aggregation may be one of the reasons which improve d33 of the material.Besides, three conjugated polymers have been synthesized successfully as main-chain NLO materials by self-polymerization and Suzuki coupling. The Td/Tg of the three polymers are 276℃/125.6℃(Poly(2-(2,6- distyryl-pyran-4-ylidene)-malononitrile)—P1), 329.5℃/118.2℃(Poly{2-[2-(2-Biphenyl-4-yl-vinyl)-6-styryl-pyran-4-ylidene]- malononitrile}—P2), and 301.7℃/149.1℃(Poly{(9,9-dihelxyl- 9H-fluorene-2,7-yldene)-alt—(2-{2,6-bis[2-(2-hexyloxyl-5-phenylene)vinyl]-pyran-4-ylidene}-malononitrile)} —P3). P1 performs the best SH intensity of 11.5 pm/V between the three polymers while p3 performs the best Tg. The temporal stability was investigated by tracing the SH coefficient as a function of temperature. The effective transition temperature of P1, P2, and P3 are 100.4℃, 86.4℃, and 81.3℃.