title: Mie Resonance-Modulated Spatial Distributions of Photogenerated Carriers in Poly(3-hexylthiophene-2,5-diyl)/Silicon Nanopillars.
abstract: Organic/silicon hybrid solar cells have great potential as low-cost, high-efficiency photovoltaic devices. The superior light trapping capability, mediated by the optical resonances, of the organic/silicon hybrid nanostructure-based cells enhances their optical performance. In this work, we fabricated Si nanopillar (NP) arrays coated with organic semiconductor, poly(3-hexylthiophene-2,5-diyl), layers. Experimental and calculated optical properties of the samples showed that Mie-resonance strongly concentrated incoming light in the NPs. Spatial mapping of surface photovoltage, i.e., changes in the surface potential under illumination, using Kelvin probe force microscopy enabled us to visualize the local behavior of the photogenerated carriers in our samples. Under red light, surface photovoltage was much larger (63 meV) on the top surface of a NP than on a planar sample (13 meV), which demonstrated that the confined light in the NPs produced numerous carriers within the NPs. Since the silicon NPs provide pathways for efficient carrier transportation, high collection probability of the photogenerated carriers near the NPs can be expected. This suggests that the optical resonance in organic/silicon hybrid nanostructures benefits not only broad-band light trapping but also efficient carrier collection.
authors.affiliation: Department of Physics, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Eunah
authors.initials: E
authors.lastname: Kim
authors.affiliation: Department of Physics, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Yunae
authors.initials: Y
authors.lastname: Cho
authors.affiliation: Department of Physics, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Ahrum
authors.initials: A
authors.lastname: Sohn
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Heewon
authors.initials: H
authors.lastname: Hwang
authors.affiliation: Department of Physics, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Y U
authors.initials: YU
authors.lastname: Lee
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Kyungkon
authors.initials: K
authors.lastname: Kim
authors.affiliation: Applied Device and Material Lab., Device Technology Division, Korea Advanced Nanofab Center (KANC), Suwon 443-270, Korea.
authors.forename: Hyeong-Ho
authors.initials: HH
authors.lastname: Park
authors.affiliation: Department of Electrical Engineering, Incheon National University, Incheon 406-772, Korea.
authors.forename: Joondong
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Physics, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: J W
authors.initials: JW
authors.lastname: Wu
authors.affiliation: Department of Physics, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Dong-Wook
authors.initials: DW
authors.lastname: Kim