Photocarrier generation in regioregular poly(3-alkylthiophene)photovoltaic cells

The photovoltaic effect in ITO/poly(3-alkylthiophene)/Al cells has been studied to elucidate the role of alkyl chain length and regularity of main chain for the alkyl groups = butyl, hexyl, decyl and octadecyl. It is found that the photocurrent is remarkably reduced for films with longer chain lengths and lack of regularity. The action spectra also depend on the alkyl chain lengths. The results are discussed in terms of the mechanism of carrier generation and transport with the data of carrier mobilities.