been prepared with conjugation length from one up to five thiophene units (1T–5T). The UV–
vis spectra, photoluminescence spectra, electrochemical data and DFT calculations show
lowering of LUMO energies and red-shift of absorption into the visible as the thiophene
chain length increases. TiO2/P3HT solar cells were prepared with prior functionalization of
the TiO2 surface by 1T–5T and studies include cells using undoped P3HT and using P3HT …