Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong Province, 518055, PR China.
Phys Chem Chem Phys. 2012 Jun 21;14(23):8391-6. doi: 10.1039/c2cp23639g. Epub 2012 May 9.
Deposition of nanostructures such as carbon nanotubes on Si wafers to make heterojunction structures is a promising route toward high efficiency solar cells with reduced cost. Here, we show a significant enhancement in the cell characteristics and power conversion efficiency by growing a silicon oxide layer at the interface between the nanotube film and Si substrate. The cell efficiency increases steadily from 0.5% without interfacial oxide to 8.8% with an optimal oxide thickness of about 1 nm. This systematic study reveals that formation of an oxide layer switches charge transport from thermionic emission to a mixture of thermionic emission and tunneling and improves overall diode properties, which are critical factors for tailoring the cell behavior. By controlled formation and removal of interfacial oxide, we demonstrate oscillation of the cell parameters between two extreme states, where the cell efficiency can be reversibly altered by a factor of 500. Our results suggest that the oxide layer plays an important role in Si-based photovoltaics, and it might be utilized to tune the cell performance in various nanostructure-Si heterojunction structures.
将纳米结构（如碳纳米管）沉积在硅片上以制造异质结结构是一种很有前途的方法，可以制造出高效率、低成本的太阳能电池。在这里，我们通过在纳米管薄膜和 Si 衬底之间的界面生长氧化硅层，显著提高了电池的特性和功率转换效率。在没有界面氧化物的情况下，电池效率从 0.5%稳步增加到具有最佳氧化层厚度约 1nm 的 8.8%。这项系统的研究表明，氧化层的形成将电荷传输从热电子发射切换为热电子发射和隧穿的混合物，并改善了整体二极管性能，这是调整电池行为的关键因素。通过控制界面氧化层的形成和去除，我们证明了电池参数在两个极端状态之间的振荡，其中电池效率可以通过 500 倍的因子可逆地改变。我们的结果表明，氧化层在基于 Si 的光伏中起着重要作用，它可能被用于调整各种纳米结构-Si 异质结结构中的电池性能。
