Coaxial multishell nanowires with high-quality electronic interfaces and tunable optical cavities for ultrathin photovoltaics
- Authors
- Kempa, Thomas J.; Cahoon, James F.; Kim, Sun-Kyung; Day, Robert W.; Bell, David C.; Park, Hong-Gyu; Lieber, Charles M.
- Issue Date
- 31-1월-2012
- Publisher
- NATL ACAD SCIENCES
- Keywords
- nanodevices; nanomaterials; nanophotonics; optical nanocavities; solar cells
- Citation
- PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, v.109, no.5, pp.1407 - 1412
- Indexed
- SCIE
SCOPUS
- Journal Title
- PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
- Volume
- 109
- Number
- 5
- Start Page
- 1407
- End Page
- 1412
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/109045
- DOI
- 10.1073/pnas.1120415109
- ISSN
- 0027-8424
- Abstract
- Silicon nanowires (NWs) could enable low-cost and efficient photovoltaics, though their performance has been limited by nonideal electrical characteristics and an inability to tune absorption properties. We overcome these limitations through controlled synthesis of a series of polymorphic core/multishell NWs with highly crystalline, hexagonally-faceted shells, and well-defined coaxial p-type/n-type (p/n) and p/intrinsic/n (p/i/n) diode junctions. Designed 200-300 nm diameter p/i/n NW diodes exhibit ultralow leakage currents of approximately 1 fA, and open-circuit voltages and fill-factors up to 0.5 V and 73%, respectively, under one-sun illumination. Single-NW wavelength-dependent photocurrent measurements reveal size-tunable optical resonances, external quantum efficiencies greater than unity, and current densities double those for silicon films of comparable thickness. In addition, finite-difference-time-domain simulations for the measured NW structures agree quantitatively with the photocurrent measurements, and demonstrate that the optical resonances are due to Fabry-Perot and whispering-gallery cavity modes supported in the high-quality faceted nanostructures. Synthetically optimized NW devices achieve current densities of 17 mA/cm(2) and power-conversion efficiencies of 6%. Horizontal integration of multiple NWs demonstrates linear scaling of the absolute photocurrent with number of NWs, as well as retention of the high open-circuit voltages and short-circuit current densities measured for single NW devices. Notably, assembly of 2 NW elements into vertical stacks yields short-circuit current densities of 25 mA/cm(2) with a backside reflector, and simulations further show that such stacking represents an attractive approach for further enhancing performance with projected efficiencies of >15% for 1.2 mu m thick 5 NW stacks.
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Collections - College of Science > Department of Physics > 1. Journal Articles
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