Analysis of carrier transport in photovoltaic structures of P3HT with CdSe nanocrystals

Hybrid photovoltaic structures made of P3HT and branched CdSe nanocrystals (NCs) with 50-90 wt% ratio were investigated. Charge Extraction by Linearly Increasing Voltage (CELIV) mobility and temperature dependent (photo-)conductivity measurements were used to analyze the charge transport. The samples with 50 wt% were photosensitive, but just a minor PV effect was observed. The photovoltaic phenomenon was pronounced in the samples containing 75 wt% or more of NCs. The Open Circuit Voltages up to 1 V were obtained. The recombination of the generated carriers was fast and could be a limiting factor of the cell current. Carrier mobility was up to (3-4) × 10−4 cm2/V s. From the fitting of mobility data the best carrier transport conditions were found in the samples with 75 wt% and 83 wt% of NCs.