We investigate the impact of P3HT regioregularity and monodispersity on the performance of sequentially solution-processed P3HT / PCBM solar cells. In such structures, P3HT layers in the devices were spin-coated onto ITO/ PEDOT:PSS out of 1,2-dichlorobenzene, followed by a layer of PCBM spin-coated out of dichloromethane. Three different batches of P3HT were utilized:  commercially available P3HT, and two different custom-made polythiophenes with higher regioregularity and monodispersity. The more regioregular and monodispersed P3HTs showed higher short circuit currents as well as higher efficiency when made into photovoltaic devices. To investigate the origin of the high short circuit current, we measured the optical absorption, fluorescence quenching, crystallinity and I-V characteristics of P3HT-only diodes of the different P3HTs. Absorption spectra and X-Ray diffraction analysis indicates different degrees of crystallinity as well as different morphologies, suggesting that controlling the nanoscale structure of polymers like P3HT is critical to the performance of P3HT/PCBM solar cells.

Impact of poly(3-hexylthiophene) regioregularity and monodispersity on the performance of organic photovoltaic devices

243rd National Meeting (2012)

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