Synthesis of conjugated polymers containing anthracene moiety and their electro-optical properties

Abstract

Both fully conjugated polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phe- nylene vinylene-alt-9,10-anthrylene vinylene] [poly(MEHPV-AV)] and conjugated/non-conjugated block copolymers poly(alkanedioxy-2-methoxy-1,4-phenylene-1,2-ethe- nylene-9, 10-anthrylene- 1,2-ehthenylene-3-methoxy-1,4-phenylene) [poly(BFMPx-AV), (x = 4, 8, and 12)] were synthesized by Horner-Emmons reaction utilizing potassium tert-butoxide. Of these synthesized polymers poly(BFMP4-AV) and poly(BFMP8-AV), which has four and six methylene groups as solubility spacer in the main chain exhibited liquid crystalline to isotropic transition in addition to the two first order transitions. Light-emitting diode (LED)s made from the organic solvent soluble poly(BFMP12-AV) as emitting layer showed blue shift in the emission spectrum compared to the one made from fully conjugated poly(MEHPV-AV). Although poly(BFMP12-AV) had higher barrier to the electron injection from cathode than poly(MEHPV-AV), the luminance efficiency of LED made from poly(BFMP12-AV) was about 25 times higher than the one made from poly(MEHPV-AV), which had fully conjugated structure. LEDs fabricated by both poly(BFMP12-AV) and poly(MEHPV-AV) exhibited Stoke's shift in the range of 155 to 168 nm from the absorption maximum due to the excimer formation between the ground and excited state anthracene groups. (C) 2000 John Wiley & Sons, Inc