Güneş enerjisi için yeni materyal-organic material-electrode interfaces in bulk-heterojunction organic solar cell


Amerikalı bilim adamları, güneş enerjisi elde etmede büyük bir engeli aşan bir materyal keşfettiklerini belirterek, bu melez materyalin güneş ışığındaki tüm enerjiyi soğurduğunu açıkladılar.

Ohio Üniversitesi’nden araştırmacılar, yakalanmalarını daha kolaylaştıracak biçimde elektronlar da üreten bu yeni malzemenin, elektrik ileten plastiği, molibdenum ve titanyum gibi metallerle biraraya getirdiğini söylediler.

ScienceDaily (Feb. 26, 2008) — The energy from sunlight falling on only 9 percent of California’s Mojave Desert could power all of the United States’ electricity needs if the energy could be efficiently harvested, according to some estimates. Unfortunately, current-generation solar cell technologies are too expensive and inefficient for wide-scale commercial applications

Solar cell schematic showing a glass substrate (A) coated with the transparent conducting anodes (B), followed by the nickel oxide electron-blocking/hole transport layer (C), which in turn is then coated with the polymer-fullerene light absorbing/charge transporting layer (D), then an additional interfacial layer of LiF (E) and, finally, the device is completed by vapor deposition of the aluminum cathodes (F). (Credit: Michael Irwin, Northwestern University)

Ohio Üniversitesi Kimya Bölümü Başkanı Prof. Malcolm Chisholm, “Böyle başka melez materyaller de var ama bizimkinin avantajı, güneş spektrumunun tamamını elde edebilmemizi sağlaması” dedi. 

Güneş ışığının, çıplak gözle görülebilecek tüm renk spektrumlarını içerdiğini belirten araştırmacılar, gözün renk olarak yorumladığının, ışığın değişik enerji düzeyi veya frekansı olduğuna işaret ediyorlar. 

Bugünkü güneş hücreleri yalnızca ışık frekansının küçük bir bölümünü yakalayabiliyor ve güneş ışığının içerdiği enerjinin küçük bir bölümünü elde edebiliyorlar. 

Araştırmalarını Proceedings of the National Academy of Sciences adlı dergide yayımlayan bilim adamları, yeni materyalin, ışıktaki enerjiyi bir seferde tamamıyla soğurabilen ilk malzeme olduğuna dikkati çekiyorlar.(ntv)

A team of Northwestern University researchers has developed a new anode coating strategy that significantly enhances the efficiency of solar energy power conversion. A paper about the work, which focuses on “engineering” organic material-electrode interfaces in bulk-heterojunction organic solar cells, is published online in the Proceedings of the National Academy of Sciences.

This breakthrough in solar energy conversion promises to bring researchers and developers worldwide closer to the goal of producing cheaper, more manufacturable and more easily implemented solar cells. Such technology would greatly reduce our dependence on burning fossil fuels for electricity production as well as reduce the combustion product: carbon dioxide, a global warming greenhouse gas

Tobin J. Marks, the Vladimir N. Ipatieff Research Professor in Chemistry in the Weinberg College of Arts and Sciences and professor of materials science and engineering, and Robert Chang, professor of materials science and engineering in the McCormick School of Engineering and Applied Science, led the research team. Other Northwestern team members were researcher Bruce Buchholz and graduate students Michael D. Irwin and Alexander W. Hains.

Of the new solar energy conversion technologies on the horizon, solar cells fabricated from plastic-like organic materials are attractive because they could be printed cheaply and quickly by a process similar to printing a newspaper (roll-to-roll processing).

To date, the most successful type of plastic photovoltaic cell is called a “bulk-heterojunction cell.” This cell utilizes a layer consisting of a mixture of a semiconducting polymer (an electron donor) and a fullerene (an electron acceptor) sandwiched between two electrodes — one a transparent electrically conducting electrode (the anode, which is usually a tin-doped indium oxide) and a metal (the cathode), such as aluminum.

When light enters through the transparent conducting electrode and strikes the light-absorbing polymer layer, electricity flows due to formation of pairs of electrons and holes that separate and move to the cathode and anode, respectively. These moving charges are the electrical current (photocurrent) generated by the cell and are collected by the two electrodes, assuming that each type of charge can readily traverse the interface between the polymer-fullerene active layer and the correct electrode to carry away the charge — a significant challenge.

The Northwestern researchers employed a laser deposition technique that coats the anode with a very thin (5 to 10 nanometers thick) and smooth layer of nickel oxide. This material is an excellent conductor for extracting holes from the irradiated cell but, equally important, is an efficient “blocker” which prevents misdirected electrons from straying to the “wrong” electrode (the anode), which would compromise the cell energy conversion efficiency.

In contrast to earlier approaches for anode coating, the Northwestern nickel oxide coating is cheap, electrically homogeneous and non-corrosive. In the case of model bulk-heterojunction cells, the Northwestern team has increased the cell voltage by approximately 40 percent and the power conversion efficiency from approximately 3 to 4 percent to 5.2 to 5.6 percent.

The researchers currently are working on further tuning the anode coating technique for increased hole extraction and electron blocking efficiency and moving to production-scaling experiments on flexible substrates.

The PNAS paper is titled “p-Type Semiconducting Nickel Oxide as an Efficiency-enhancing Anode Interfacial Layer in Polymer Bulk-heterojunction Solar Cells.”

25 Ekim, 2008 tarihinde Bilim, Science, Elektrik, Electric, Enerji, Energy, Güneş, Solar, Teknoloji,technology, Verimlilik Saving içinde yayınlandı ve , , , , , , , , , , , , , , , , , , , olarak etiketlendi. Kalıcı bağlantıyı yer imlerinize ekleyin. Yorum yapın.

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