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Three-dimensional nanopillar-array photovoltaics on low-cost and flexible substrates


Solar energy represents one of the most abundant and yet least harvested sources of renewable energy. In recent years, tremendous progress has been made in developing photovoltaics that can be potentially mass deployed1,2,3. Of particular interest to cost-effective solar cells is to use novel device structures and materials processing for enabling acceptable efficiencies4,5,6. In this regard, here, we report the direct growth of highly regular, single-crystalline nanopillar arrays of optically active semiconductors on aluminium substrates that are then configured as solar-cell modules. As an example, we demonstrate a photovoltaic structure that incorporates three-dimensional, single-crystalline n-CdS nanopillars, embedded in polycrystalline thin films of p-CdTe, to enable high absorption of light and efficient collection of the carriers. Through experiments and modelling, we demonstrate the potency of this approach for enabling highly versatile solar modules on both rigid and flexible substrates with enhanced carrier collection efficiency arising from the geometric configuration of the nanopillars.

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Figure 1: CdS/CdTe SNOP cells.
Figure 2: SNOP cell at different stages of fabrication.
Figure 3: Performance characterization of a representative SNOP cell.
Figure 4: Effects of the nanopillar geometric configuration on the device performance.
Figure 5: Mechanically flexible SNOP cells.


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We acknowledge G. F. Brown and J. Wu for help with simulations. This work was financially supported by Berkeley Sensor and Actuator Center. J. C. H. acknowledges an Intel Graduate Fellowship. All fabrication was carried out in the Berkeley Microfabrication Laboratory. The solar-cell experimental characterization was done at LBNL, and was supported by the Helios Solar Energy Research Center, which is supported by the Director, Office of Science, Office of Basic Energy Sciences of the US Department of Energy under Contract No. DE-AC02-05CH11231.

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Z.F., H.R., J.D., A.M., O.E., Y.-L.C. and A.J. designed the experiments. Z.F., H.R., J.D., A.M., O.E., Y.-L.C., J.C.H., T.T., L.A.R., S.N., K.Y., M.W., J.W.A. and A.J. carried out experiments. Z.F., P.W.L., J.W.A. and A.J. carried out simulations. Z.F., H.R., J.D., A.M., O.E., Y.-L.C., J.C.H., T.T., L.A.R., P.W.L., S.N., K.Y., J.W.A. and A.J. contributed to analysing the data. Z.F. and A.J. wrote the paper and all authors provided feedback.

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Correspondence to Ali Javey.

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Fan, Z., Razavi, H., Do, Jw. et al. Three-dimensional nanopillar-array photovoltaics on low-cost and flexible substrates. Nature Mater 8, 648–653 (2009).

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