Light-emitting electrochemical cells based on poly(9,9-bis(3,6-dioxaheptyl)-fluorene-2,7-diyl)

Abstract

To enhance color stability of light-emitting electrochemical cell (LEC) made with poly(9,9-bis(3,6-dioxaheptyl)-fluorene-2,7-diyl) (BDOH-PF), BDOH-PF end-capped with anthracene was prepared by Ni(0) mediated polymerization. Moreover, a copolymer of 9,9-bis(3,6-dioxaheptyl)-2,7-dibromofluorene and 9,10-dibromoanthracene which was also end-capped with anthracene, was synthesized by the same polymerization method. Less excimer emission in photoluminescence (PL) spectra were observed in these polymers compared to the previous BDOH-PF. LECs were fabricated using blends of lithium triflate and the prepared polymers. These LECs showed high brightness at low applied voltages. In the electroluminescence (EL) spectra, narrow blue emission was observed initially in these LECs and the EL spectra were getting broader because of excimer formation. End capping with anthracene and/or copolymerization with anthracene led to strong inhibition of excimer formation though it was not suppressed completely.