Ionic Liquid‐Supported Vat Dye (Congo Red)‐Based Donor–Acceptor Type Conjugated Polymeric Material as Photosensitizer for Dye‐Sensitized Solar Cells

The greatest candidates for organic dyes that exhibit redox activities are vat dyes. Polymers based on vat dyes become effective sensitizer material for dye‐sensitized solar cells (DSSCs) because of their higher absorption coefficient and redox properties by reducing the polymeric film thickness. Herein, an ionic liquid (IL)‐supported D–A type conjugated polyimide sensitizer based on vat dye Congo red and pyromellitic dianhydride is synthesized via condensation polymerization technique. This polymeric material is doped with BF 3 and supported with a minimal quantity of IL for better conductivity results and interface creation. The synthesized polyimide shows altruistic oxidoreduction properties with a narrow bandgap of 1.96 eV. Additionally, it comprises conjugated electrons having a backbone system that shows good electrical conductivity (>10 −4 S cm −1 ) and becomes a semiconducting material. To determine the photovoltaic characteristics of the synthesized polymeric material, electrode fabrication and DSSC are carried out. The estimated photovoltaic characteristics are J sc = 0.2324 mA cm −2 , fill factor = 0.6906, and V oc = 0.2380 V. The power conversion efficiency of the device is obtained at 0.04%. The film‐forming property of polymeric sensitizer can reduce electron passivation in the cell. These observed properties of polymeric sensitizer material hardly claim their suitability for DSSCs applications.