Peking University, Nov.23, 2011: Peking University (PKU) Professor Peng Lianmao published Research Efficient Photovoltage Multiplication in Carbon Nanotubes on Nature Photonics (2011, 5, PP.672-676), with PhD candidates from PKU School of Electronics Engineering and Computer Science, Yang Leijing and Wang Shengfu, as co-writers.

Nature Photonics is one of the periodicals belongs to the journal Nature. The research paper contains major breakthrough in the application of nanelectronic. . It is also a milestone for both the field of nanoelectronic and Professor Peng Lianmao’s Team. Considering that natural resources are becoming rarer and rarer, solar power has many unsurpassable advantages as an alternative energy source. At present, global researches in solar photovoltage mainly focus on the study of photovoltaic devices using new nanomaterials.

Carbon nanotubes are direct-bandgap materials that are not only useful for nanoelectronic applications, but also have the potential to make a significant impact on the next generation of photovoltaic technology. A semiconducting single-walled carbon nanotube (SWCNT) has an unusual band structure which allowed high-efficiency carrier multiplication effects to be predicted and observed. It also led to the discovery of  films of SWCNTs with absorption close to 100% . Other important features for photovoltaic applications include high mobility and the availability of olmic contacts for both electrons and holes. However, the photovoltage generated from a typical semiconducting SWCNT is less than 0.2V, which is too small for most practical photovoltaic applications. Given this background, the researchers aimed to multiply the value by using virtual contacts at the carbon nanotube, which turn out to be an important and challenging job.

Professor Peng and his team worked out an approach; the key to success was the introduction of a local virtual contact to the CNT. This contact is virtual in the sense that it is not intended to be connected to the external circuit. In one example, more than 1.0V is generated from a 10-mm-longcarbon annotate with a single-cell photovoltage of 0.2V. This work was discovered based on the forward researches conducted by the same team.

In 2008, the research group put forward a method to form carbon nanotube (CNT) diodes using asymmetrically contacts between electrodes. This research finding was published on Advanced Materials (2008, 20, 3258). On this basis, using almost the same but improved methods, the team invented the first carbon tube infrared light-emitting diode (LED), Nano Letters (2011, 11, 23) reported.

The study was supported by the China's National Basic Research Program, and funded by the National Natural Science Fund Committee (NNSFC).

Written by: Jiang Zhaohui
Edited by: Arthars
Source: PKU News (Chinese)