Facile synthesis of poly(3,4-ethylenedioxythiophene) and poly(bis-3,4-ethylenedioxythiophene) via UV-irradiation polymerization and their reduction/iodine oxidation post-treatment for the application as counter electrodes for dye-sensitized solar cells

Abstract Conductive poly(3,4-ethylenedioxythiophene) and poly(bis-3,4-ethylenedioxythiophene) had been firstly synthesized by UV-irradiation of monomers of 5,7-diiodo-2,3-dihydro-thieno[3,4-b][1,4]dioxine and 7,7′-diiodo-2,3,2′,3′-tetrahydro-[5,5']bi[thieno[3,4-b][1,4]dioxinyl]. To prepare conductive polymer counter electrodes for dye-sensitized solar cell, their UV polymerization (UVP) optimization processes had been carefully carried out. In order to further improve photo-to-electric conversion efficiency, these UVP-polymer electrodes were treated through reduction-reoxidation (N 2 H 4 /I 2 ) process. Our results showed that with and without post-treatment, poly(3,4-ethylenedioxythiophene) counter electrode demonstrated DSC conversion efficiencies of 7.08% and 6.64% respectively, while the Pt electrode showed 7.78%. Our study indicated that UVP is an alternative facile method to prepare poly(3,4-ethylenedioxythiophene) and poly(bis-3,4-ethylenedioxythiophene) films and the iodine post-treated UVP-poly(3,4-ethylenedioxythiophene) counter electrode showed comparable performance to those obtained through traditional chemical oxidation or electrochemical polymerization methods.