Molecular orientation of regioregular poly(3-hexylthiophene) film

Ikeura, Hiromi*; Sekiguchi, Tetsuhiro  

The regioregularity (2head-to-5'tail regularity) for organic semiconductor polymer backbone plays a dominant role in controlling molecular orientation, thus strongly influences the performance of organic solar cells. In the present work, we have investigated the orientation structure of donor regioregular poly(3-hexylthiophene) (P3HT) films using angle-resolved near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy. The films on silicon substrates were prepared by solution spin cast method. The lowest unoccupied molecular orbital (LUMO) levels were obtained from the edge energies of S 1s inner-shell excitation, from which energy conversion efficiencies for solar cells were estimated. The results of them were compared with those which were measured for amorphous P3HT films.