Carbon nanotubes bring a new dawn for solar cells
U.S. scientists have used carbon nanotubes to produce new type of solar cells to absorb the same amount of photons can produce more light under the current, its efficiency will be superior to the current PV Laptop battery cells. They prove that carbon nanotubes made of light emitting diode (photodiode) absorbs a photon can generate multiple electron-hole pairs (electron-holepair), unlike the conventional LED can only produce one group. Cornell University NathanGabor involved in the study, said the technology, if applied to large-size solar cell conversion efficiency is bound to break away from restrictions.
The current PV Latitude D610 battery cells absorb a photon of each produce at most a group of electron-hole pairs, however, Cornell University research team led by PaulMcEuen using single-walled carbon nanotubes made of photovoltaic Latitude D620 battery cells, breaking this restriction. This device consists of approximately 3 ~ 4μm, ranging from 1.5 ~ 3.6nm diameter carbon control into the carbon tubes are placed on an insulating substrate between the electrodes, the electrode bias is applied, the electrodes of the carbon nanotubes to form a pn junction light emitting diode.
The researchers irradiated by laser light emitting diode, while the carbon tube is applied to reverse bias Acer Aspire One battery , and to monitor the photocurrent. The results at temperatures lower than 90K and the reverse bias current is applied and when the child was observed more heavy generation. As this bias increases, the current was step-like increase Aspire 3000 battery. If the sub-raising incident light energy, the current ladder will be widened.
Usually a photon can only be an electronic excitation up a sub-band, Cornell Panel finds that the generation of multiple electron-hole pairs is due to photons to provide carbon nanotube electronics a lot more energ of XPS m140 BATTERY, making a second or more of the electronic energy band is also diode can move and inspire other electronics, and when the second band of the carrier to obtain enough energy to stimulate additional electronic time, the resulting change in current occurs ladder.
Gabor pointed out that the second energy band implies the presence of threshold used up almost all of the above-mentioned process of the remaining photon energy, coupled with the Pavilion DV1000 battery energy of the electric field, along with a single electron is used to convert multi-electron, which for the achievement of high performance solar cells The ultimate goal is important, because the latter is almost 100 percent in the pursuit of the light used to stimulate electron-hole pairs.
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