Photoexcitation Dynamics of Coupled Semiconducting Carbon Nanotube Thin Films
详细信息 查看全文
- 作者：Randy D. Mehlenbacher ; Meng-Yin Wu ; Maksim Grechko ; Jennifer E. Laaser ; Michael S. Arnold ; Martin T. Zanni
- 刊名：Nano Letters
- 出版年：2013
- 出版时间：April 10, 2013
- 年：2013
- 卷：13
- 期：4
- 页码：1495-1501
- 全文大小：343K
- 年卷期：v.13,no.4(April 10, 2013)
- ISSN：1530-6992
文摘
Carbon nanotubes are a promising means of capturing photons for use in solar cell devices. We time-resolved the photoexcitation dynamics of coupled, bandgap-selected, semiconducting carbon nanotubes in thin films tailored for photovoltaics. Using transient absorption spectroscopy and anisotropy measurements, we found that the photoexcitation evolves by two mechanisms with a fast and long-range component followed by a slow and short-range component. Within 300 fs of optical excitation, 20% of nanotubes transfer their photoexcitation over 5鈥?0 nm into nearby nanotube fibers. After 3 ps, 70% of the photoexcitation resides on the smallest bandgap nanotubes. After this ultrafast process, the photoexcitation continues to transfer on a 10 ps time scale but to predominantly aligned tubes. Ultimately the photoexcitation hops twice on average between fibers. These results are important for understanding the flow of energy and charge in coupled nanotube materials and light-harvesting devices.