Synthesis and Photovoltaic Properties of Fluorene-Based Copolymers with Thiophene Heterocycle on the Side Chain

High molecular weight, readily soluable copolymer was prepared from 9,9-di (2-thienyl-hexyl) fluorene (TF) 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9-di octyl fluorene and narrow band gap comonomer 2,3-dimethyl- 5,8-(5-bromo)-dithien-2-yl-quinoxalines (DTQU) using pallad- ium catalyzed Suzuki coupling methods. To compare the copolymer to this without thiophene in the C9 side chain of fluorene, the copolymer from DOF and DTQU was synthesized. The electrochemical, optical and photovoltaic properties of the copolymers were studied. The absorption spectra of the copolymers measured in thin films display two absorption peaks. The power conversion efficiency achieved in the device configuration ITO/PEDT/FT- DTQU:PCBM (1:2)/Al is 0.85% with open-circuit voltage (Voc) 0.8V. Further improvement by manipulating polymer/electrode interface and further investigation of more polyfluorene copolymers with narrow band gap aryl-hetero cycle units on the side chain is in progress.

Synthesis and Photovoltaic Properties of Fluorene-Based Copolymers

A serial of polyfluorene copolymers have been developed by covalently attaching thiophene units to the side chain of polyfluorene with an alkyl spacer by means of Pd-catalyzed Suzuki coupling reactions. The electrochemical, photophysical and photovoltaic properties of the copolymers were studied. The absorption spectra of the copolymers measured in thin films display two absorption peaks. The power conversion efficiency achieved in the device configuration ITO/PEDT/ PFO-FT-DBT: PCBM (1:2)/Al is 0.83% with open-circuit voltage (Voc) 0.75V. Further investigation of more polyfluorene copolymers with narrow band gap aryl-hetero cycle units on the side chain is in progress.

Phosphazene XXXIII.

4-Amino-diphosphazene (1) haben sich bereits mehrfach zum Aufbau von Phosphazen-Hetero-cycle bewährt 2-4. Sie bringen dazu eine bifunktionelle fünfgliedrige PN-Kette und die Nucleophilie eines Phosphinimins mit. Ihre jetzt untersuchte Umsetzung mit Thiophosphonsäureanhydriden (2), deren Vierring durch Basen bekanntermaßen leicht aufgespalten wird, führt zu einer neuen Synthese von Cyclotriphosphazenen bestimmter Substitution.