Electrical Engineering Department, University of California at Los Angeles, Los Angeles, California 90095, United States.
Nano Lett. 2013 Apr 10;13(4):1632-7. doi: 10.1021/nl400083g. Epub 2013 Mar 13.
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-tin-oxide (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.
半导体纳米材料最近推动了许多光子科学领域的发展。纳米柱（NP）阵列已被光伏（PV）界作为高效太阳能吸收器进行了研究，与平面结构相比，具有潜在的材料/成本降低优势。尽管经过模型预测，但在集成到实际 PV 器件中后，表面复合和不良的光管理会限制其实验效率。在这封信件中，我们将光电建模与通过选择性区域、无催化剂外延生长并通过外延窗口层覆盖的核壳 GaAs NP 直接带隙阵列的实验结果进行了关联，其效率为 7.43%。在电学方面，经过外延钝化后，残余表面态密度仍会部分影响开路电压的提高。在光学方面，圆顶形铟锡氧化物（ITO）顶电极充当亚波长透镜的二维（2-D）周期性阵列，将 NP 活性体积内的光态局域密度聚焦。这些器件通过协同控制异质外延和最终结构的光管理，为高效 NP 基 PV 提供了一条途径。
