Geballe Laboratory for Advanced Materials, Stanford University, California 94305, USA.
Nano Lett. 2010 Feb 10;10(2):439-45. doi: 10.1021/nl9036627.
Photovoltaic (PV) cells can serve as a virtually unlimited clean source of energy by converting sunlight into electrical power. Their importance is reflected in the tireless efforts that have been devoted to improving the electrical and structural properties of PV materials. More recently, photon management (PM) has emerged as a powerful additional means to boost energy conversion efficiencies. Here, we demonstrate an entirely new PM strategy that capitalizes on strong broad band optical antenna effects in one-dimensional semiconductor nanostructures to dramatically enhance absorption of sunlight. We show that the absorption of sunlight in Si nanowires (Si NWs) can be significantly enhanced over the bulk. The NW's optical properties also naturally give rise to an improved angular response. We propose that by patterning the silicon layer in a thin film PV cell into an array of NWs, one can boost the absorption for solar radiation by 25% while utilizing less than half of the semiconductor material (250% increase in the light absorption per unit volume of material). These results significantly advance our understanding of the way sunlight is absorbed by one-dimensional semiconductor nanostructures and provide a clear, intuitive guidance for the design of efficient NW solar cells. The presented approach is universal to any semiconductor and a wide range of nanostructures; as such, it provides a new PV platform technology.
光伏 (PV) 电池可以将阳光转化为电力，作为一种几乎无限的清洁能源。人们为提高光伏材料的电气和结构性能付出了不懈的努力，这反映出其重要性。最近，光子管理 (PM) 已经成为提高能量转换效率的一种强大的附加手段。在这里，我们展示了一种全新的 PM 策略，利用一维半导体纳米结构中的强宽带光学天线效应来显著提高太阳光的吸收。我们表明，硅纳米线 (SiNWs) 中的太阳光吸收可以大大增强超过体相。纳米线的光学性质也自然导致了对角度响应的改善。我们提出，通过将薄膜光伏电池中的硅层图案化成纳米线阵列，可以在使用不到一半半导体材料的情况下（材料单位体积的光吸收增加 250%），将太阳辐射的吸收提高 25%。这些结果显著提高了我们对一维半导体纳米结构吸收太阳光的方式的理解，并为高效纳米线太阳能电池的设计提供了清晰直观的指导。所提出的方法适用于任何半导体和多种纳米结构；因此，它提供了一种新的光伏平台技术。
