Direct-Bandgap Epitaxial Core鈥揗ultishell Nanopillar Photovoltaics Featuring Subwavelength Optical Concentrators
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- 作者：Giacomo Mariani ; Zhengliu Zhou ; Adam Scofield ; Diana L. Huffaker
- 刊名：Nano Letters
- 出版年：2013
- 出版时间：April 10, 2013
- 年：2013
- 卷：13
- 期：4
- 页码：1632-1637
- 全文大小：352K
- 年卷期：v.13,no.4(April 10, 2013)
- ISSN：1530-6992
文摘
Semiconductor nanomaterials have recently fueled numerous photonic scientific fields. Arrays of nanopillars (NPs) have been examined by the photovoltaic (PV) community as highly efficient solar absorbers, with potential material/cost reductions compared to planar architectures. Despite modeled predictions, experimental efficiencies are limited by surface recombination and poor light management, once integrated in a practical PV device. In this Letter, we correlate optoelectronic modeling with experimental results for direct-bandgap arrays of core-multishell GaAs NPs grown by selective area, catalyst-free epitaxy and capped by epitaxial window layers, with efficiencies of 7.43%. Electrically, improved open-circuit voltages are yet partly affected by residual surface state density after epitaxial passivation. Optically, dome-shaped indium鈥搕in鈥搊xide (ITO) top electrode functions as a two-dimensional (2-D) periodic array of subwavelength lenses that focus the local density of optical states within the NP active volume. These devices provide a path to high-efficiency NP-based PVs by synergistically controlling the heteroepitaxy and light management of the final structure.