近日，一種最有前途的制作廉價且效率可觀的光伏電池技術再一次走上了降價之路。在加拿大多倫多大學的科學家們發現，便宜的鎳在關鍵的電接觸上面可以像黃金一樣通過其太陽能電池的膠體量子點收集的電流。
然而，Professor Ted Sargent''''s group的光伏研究項目負責人Lukasz Brzozowski說，使用的鎳的改變又可以降低原本就很便宜的材料費用的40%-80%。在2010年7月12日，美國物理協會（AIP）出版發行了他們目前的研究-應用物理快報（Applied Physics Letters）。
量子點是一種半導體材料，其使用成本低，在液體溶液中能夠產生高流動性的化學反應。由于大小不同，量子點的性質也會變化，量子點可配合照明光譜。
例如，一半的陽光都在紅外波段，而其中大部分是不能以硅為基礎的太陽能電池收集。Sargent團隊率先開發和設計了量子點太陽能電池收集可見光和紅外光。他們的電力轉換效率高達5%,而其目標是在商業化之前達到10%。
事實上，起初，鎳并沒有用在此項目中。后來,在鎳之間添加一納米的氟化鋰,量子點就制造出了一個屏障來,阻止其受污染，最后電池效率就達到了預期水平. 這次加拿大研究人員的發現意味著最近太陽能電池的里程碑。
New Inexpensive Solar Cell Design
One of the most promising technologies for making inexpensive but reasonably efficient solar photovoltaic cells just got much cheaper. Scientists at the University of Toronto in Canada have shown that inexpensive nickel can work just as well as gold for one of the critical electrical contacts that gather the electrical current produced by their colloidal quantum dot solar cells.
The change to nickel can reduce the cell''''s already low material costs by 40 to 80 percent, says Lukasz Brzozowski, the director of the Photovoltaics Research Program in Professor Ted Sargent''''s group. They present their research in the July 12, 2010 issue of Applied Physics Letters, which is published by the American Institute of Physics (AIP).
Quantum dots are nanoscale bits of a semiconductor material that are created using low-cost, high-throughput chemical reactions in liquid solutions. Since their properties vary according to their size, quantum dots can be made to match the illumination spectrum.
Half of all sunlight, for example, is in the infrared wavelengths, most of which cannot be collected by silicon-based solar cells. Sargent''''s group has pioneered the design and development of quantum dot solar cells that gather both visible and infrared light. They have reached a power-conversion efficiency as high as 5 percent and aim to improve that to 10 percent before commercialization.
At first, nickel did not appear to do the job. Adding just one nanometer of lithium fluoride between the nickel and the dots created a barrier that stopped the contamination, and the cell''''s efficiency jumped back up to the expected level.
This is the latest of several recent solar-cell milestones by the Canadian researchers. "We have been able to increase dramatically the efficiency of our photovoltaics over the last several years and continue to hold the performance world records," Professor Sargent said.
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