A new polymeric photosensitizer for dye-sensitized solar cell with porous TiO2 from forest carbon resources

A series of new lignin derivatives (lignophenols) containing phenol, p-cresol, catechol, resorcinol and pyrogallol synthesized from Hinoki (Chamaecyparis obtusa) and Douglas fir (Pseudotsuga menziessi) as softwood and beech (Fagas crenata) as hardwood was investigated as sensitizers for a dye-sensitized solar cell (DSSCs) of porous TiO2 under the irradiation of 150 W Xe lamp. For example, LPs–DSSCs of hinoki-ligno-p-cresol, directly derived from hinoki native lignin showed Voc=0.34 V, Isc=0.65 mA cm−2, ff=0.49 and η=0.11% under AM 1.5 (100 W m−2). The strong interactions between lignophenols and TiO2 surface were estimated by UV-Vis and FT-IR spectra. The importance of interactions between phenolic hydroxyl groups and TiO2 surface was discussed by FT-IR, solid UV-Vis spectra and 1H NMR. The effects of chemical modifications were discussed using acethylated lignophenols (LPsOAc) or re-cycled lignophenols, treated by 0.5 M NaOH at 413 K (LPs–SF413) or 443 K (LPs–SF443). These results implied interactions between LPs and TiO2 were consisted of anchors and stacking on TiO2.