title: The synergistic effect of nanocrystal integration and process optimization on solar cell efficiency.
abstract: This paper investigates the roles of semiconducting single-walled carbon nanotubes (SWNTs) and metallic SWNTs in the SWNT/poly(3-hexylthiophene) (P3HT)-based photovoltaic conversion system. SWNTs containing different fractions of semiconducting nanotubes were conjugated with P3HT by virtue of π-π interaction. The energy transfer and carrier transport mechanisms in the photovoltaic composites were experimentally investigated by optical absorption spectroscopy, photoluminescence spectroscopy and carrier mobility measurements. At low loading of SWNTs, a high percentage of semiconducting nanotubes result in diminished non-radiative decay of exciton and lower carrier mobility, causing higher open circuit voltage and lower photocurrent. At an optimized morphology, SWNT/P3HT/phenyl-C61-butyric acid methyl ester (PCBM) hybrid-based solar cells demonstrated much higher photocurrent than a reference solar cell (P3HT:PCBM) due to the improved carrier mobility. Further thermal annealing of the devices significantly increased the open circuit voltage to 610 mV, resulting in an 80% increase of power conversion efficiency in comparison to the reference solar cell. These results are expected to lay a foundation for the integration of various nanocrystals into solar cells for efficient photovoltaic conversion.
authors.affiliation: Department of Industrial Engineering, Texas Tech University, 2500 Broadway, PO Box 43061, Lubbock, TX 79409, USA.
authors.forename: Liqiang
authors.initials: L
authors.lastname: Ren
authors.forename: Shiren
authors.initials: S
authors.lastname: Wang
authors.forename: Mark
authors.initials: M
authors.lastname: Holtz
authors.forename: Jingjing
authors.initials: J
authors.lastname: Qiu