Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Nano Lett. 2011 Feb 9;11(2):455-60. doi: 10.1021/nl1031343. Epub 2010 Dec 17.
We have employed thin films of highly purified semiconducting carbon nanotubes as near-infrared optical absorbers in heterojunction photovoltaic and photodetector devices with the electron acceptor C(60). In comparison with previous implementations of more electrically heterogeneous carbon nanotube/C(60) devices, we have realized a 10× gain in zero-bias quantum efficiency (QE) and even more substantial gains in power conversion efficiency (η(p)). The semiconducting nanotube/C(60) heterojunctions are highly rectifying with a peak external QE, internal QE, and η(p) of 12.9 ± 1.3, 91 ± 22, and 0.6%, respectively, in the near-infrared. We show that the device efficiency is determined by the effective length scale for exciton migration in the nanotube films, confirm the high internal QE via photoluminescence quenching, and demonstrate that the driving force for exciton dissociation at the fullerene-fullerene heterointerface is optimized for diameters <1.0 nm. These results will guide the development of next-generation high-performance carbon nanotube-based solar cells and photosensitive devices.
我们使用高度纯化的半导体碳纳米管薄膜作为近红外光吸收体，应用于异质结光伏和光电探测器器件中，电子受体为 C(60)。与之前实现的更具电异质性的碳纳米管/C(60)器件相比，我们实现了零偏置量子效率 (QE) 的 10 倍增益，甚至在功率转换效率 (η(p))方面也有更大的增益。半导体纳米管/C(60)异质结具有高度整流性，在近红外光下，峰值外量子效率 (QE)、内量子效率 (QE) 和 η(p) 分别为 12.9 ± 1.3%、91 ± 22% 和 0.6%。我们表明，器件效率取决于纳米管薄膜中激子迁移的有效长度尺度，通过光致发光猝灭来确认高内量子效率，并证明在富勒烯-富勒烯异质界面处激子解离的驱动力对于直径 <1.0nm 的碳纳米管是最佳的。这些结果将指导下一代高性能碳纳米管基太阳能电池和光敏器件的发展。
