energi terbarukan: CAT SURYA … 231211


Jum’at, 23 Desember 2011 | 10:23 WIB
Cat Surya, Memproduksi Listrik dari Cat Dinding

TEMPO.CO , Notre Dame – Coba bayangkan jika lapisan cat luar rumah Anda bisa menghasilkan listrik dari sinar matahari. Lalu, listrik itu dapat digunakan untuk menyalakan perabot di dalam rumah layaknya listrik dari perusahaan pemasok energi. Praktis dan efisien.

Kini sebuah tim peneliti dari University of Notre Dame, Amerika Serikat, berhasil melakukan loncatan ke depan tentang visi cat penghasil listrik dengan menciptakan “cat surya” berbiaya rendah. Cat ini menggunakan semacam partikel semikonduktor berukuran nano untuk memproduksi energi listrik.

“Kami ingin melakukan sesuatu yang transformatif, bergerak maju melebihi teknologi solar sel berbahan dasar silikon yang selama ini berkembang,” kata Prashant Kamat, profesor ilmu pengetahuan bidang kimia dan biokimia di Notre Dame’s Center for Nano Science and Technology (NDnano), yang memimpin penelitian.

NDnano adalah salah satu pusat pengembangan teknologi nano termaju. Visi NDnano adalah mempelajari dan memanipulasi sifat bahan dan perangkat, serta mengetahui reaksi dan interaksinya dengan sistem kehidupan pada skala nano.

Kamat mengatakan, dengan menggabungkan kekuatan memproduksi partikel nano yang disebut titik-titik kuantum menjadi senyawa yang tersebar, ia telah membuat satu mantel cat surya yang dapat digunakan pada setiap permukaan konduktif tanpa perlu peralatan khusus.

Pencarian atas bahan penghasil listrik difokuskan pada partikel titanium dioksida berukuran nano yang dilapisi senyawa cadmium sulfida atau cadmium selenida. Partikel gabungan tersebut selanjutnya direndam dalam campuran air dan alkohol untuk menghasilkan semacam pasta dan dijadikan cat.

Ketika cat tersebut dioleskan ke bahan konduktif transparan, lalu dikenai sinar, ia akan menghasilkan listrik.

“Tingkat efisiensi perubahan sinar menjadi listrik sebesar satu persen. Angka itu memang masih jauh di belakang tingkat efisiensi solar sel berbahan silikon, yakni sebesar 10-15 persen,” kata Kamat.

Kendati demikian, cat surya dapat diproduksi dalam skala besar secara murah. “Jika kita dapat menemukan cara meningkatkan efisiensinya, kita dapat membuat perbedaan besar dalam memenuhi kebutuhan energi di masa depan,” ujar Kamat.

Kini Kamat dan timnya juga berencana mempelajari cara mengembangkan stabilitas bahan penghasil listrik baru temuannya.

SCIENCEDAILY | MAHARDIKA SATRIA HADI

Nanotechnology for Next Generation Solar Cells

Prashant V. KamatExecutive Editor and George C. SchatzEditor-in-Chief
J. Phys. Chem. C, 2009, 113 (35), pp 15473–15475
DOI: 10.1021/jp905378n
Publication Date (Web): August 4, 2009
Copyright © 2009 American Chemical Society
CASSection:
Electrochemical, Radiational, and Thermal Energy Technology

This editorial marks the introduction of a new feature for The Journal of Physical Chemistry: JPC Virtual Issues. Each Virtual Issue will consist of a selection of 40 or fewer articles, including Reviews and Feature Articles, published in JPC over the past two years that report important advances in different subdisciplines of physical chemistry and will be accessible through the JPC A/B/C home pages. For reference, the introduction describing each issue, complete with a list of highlighted articles, will be published as editorials in the journal. It is our hope that readers of JPC will find these topical collections of articles to be a valuable resource in learning about the state of the art in a subdiscipline of physical chemistry.

This inaugural JPC Virtual Issue (http://pubs.acs.org/page/jpccck/vi/1) focuses on the important area of solar cell research. The research papers selected from various laboratories around the world provide valuable fundamental information as well as insights into the mechanisms of energy conversion processes, kinetic and thermodynamic limitations, and methodologies to improve energy conversion efficiency.

The emergence of new strategies in the design of energy conversion and storage systems during the past couple of years has resulted in many fascinating and important research developments. Of particular interest are efforts to design new nanostructured architectures and molecular assemblies for the next generation of solar cells. Three different types of solar cells based on the advances in nanotechnology have emerged: (i) dye sensitized solar cells (DSSC), (ii) hybrid organic solar cells, and (iii) quantum dot solar cells. The capture and conversion of light energy in these solar cells is facilitated by modifying a nanostructured semiconductor interface with a dye, conjugate polymer, or semiconductor nanocrystals, respectively. Improving the efficiency of photoinduced charge separation and transport of charge carriers across these nanoassemblies remains a challenge.

The basic concepts involved in the development of nanoassemblies for light energy harvesting applications are featured in ref 1. The reviews of Peter, Hodes, and Kamat(2-4) on the dye-sensitized nanocrystalline solar cells (DSSC) and quantum dot solar cells highlight recent progress including the processes that dictate the photoconversion efficiency. The thermodynamic and kinetic criteria for successful cell design are outlined in these articles. Imahori has presented strategies for utilizing photoinduced charge separation in donor−acceptor molecules to fabricate nanostructured semiconductor based solar cells.(5)

The photosensitization of nanostructured TiO2 films with visible light absorbing dyes has led to the development of DSSC with efficiencies greater than 10%. Although there have been significant successes, certain challenges remain in DSSC research. The focus of recent research has been on maximizing photoconversion efficiency by molecular design, developing new nanostructure architectures, and establishing the fundamental processes in light harvesting assemblies.(6-16) The use of ionic liquids as a replacement for common solvents has shown promise in the development of solid state DSSC.(17-19)

The morphology and optoelectronic properties of polythiophene- and polyphenylenevinylene-based conjugated polymers and oligomers continue to be evaluated for aiding the development of organic hybrid solar cells.(20-23) Insight into the origin of disorder in the system, the degree of carrier localization, and the role of chain interactions has been attempted by classical molecular dynamics simulations(24) and by monitoring the ultrafast decay component in the polarization anisotropy.(25) Time-resolved microwave conductivity experiments have shown that the phase separation of the polymer and PCBM ([6,6]-phenyl C-61-butyric acid methyl ester) achieved through controlled annealing retards the recombination of charge carriers and thus facilitates charge collection in a solar cell.(26) Conductive atomic force microscopy (c-AFM) has also been recently employed to map the electronic properties of conducting polymers.(27) New strategies are required to improve the performance of these cells by extending the absorption into the red and overcoming the limitations induced by photodegradation.

Research emphasis in the area of quantum dot solar cells has been aimed at utilizing the unique optical and electronic properties of semiconductor nanocrystals for capture and conversion of light energy.(28-32) The size-dependent properties of CdSe, CdS, and other semiconductor nanocrystals make them suitable for tuning the photoresponse of solar cells. However, the efficiencies of quantum dot sensitized solar cells have remained rather low (1−2%) compared to DSSC and organic hybrid cells. The semiconductor/electrolyte interface plays a crucial role in dictating hole transfer and anodic corrosion of the semiconductor. More concerted efforts are needed to design functionalized or hybrid nanostructures in order to improve the efficiency of these solar cells and minimize the photocorrosion processes.(33, 34)

As the quest for energy solutions continues, we can expect many new exciting discoveries to aid in the capture and conversion of light energy economically and efficiently. Needless to say physical chemistry will continue to play an essential role in providing a fundamental understanding of light induced processes and charge transfer events.

Notre Dame researchers develop paint-on solar cells
Arnie Phifer • Date: December 21, 2011

Imagine if the next coat of paint you put on the outside of your home generates electricity from light—electricity that can be used to power the appliances and equipment on the inside.

A team of researchers at the University of Notre Dame has made a major advance toward this vision by creating an inexpensive “solar paint” that uses semiconducting nanoparticles to produce energy.

This paste of cadmium sulfide-coated titanium dioxide nanoparticles could turn large surfaces into solar cells. (Photo Credit: ACS Nano)

“We want to do something transformative, to move beyond current silicon-based solar technology,” says Prashant Kamat, John A. Zahm Professor of Science in Chemistry and Biochemistry and an investigator in Notre Dame’s Center for Nano Science and Technology (NDnano), who leads the research.

“By incorporating power-producing nanoparticles, called quantum dots, into a spreadable compound, we’ve made a one-coat solar paint that can be applied to any conductive surface without special equipment.”

The team’s search for the new material, described in the journal ACS Nano, centered on nano-sized particles of titanium dioxide, which were coated with either cadmium sulfide or cadmium selenide. The particles were then suspended in a water-alcohol mixture to create a paste.

When the paste was brushed onto a transparent conducting material and exposed to light, it created electricity.

Prashant Kamat

“The best light-to-energy conversion efficiency we’ve reached so far is 1 percent, which is well behind the usual 10 to 15 percent efficiency of commercial silicon solar cells,” explains Kamat.

“But this paint can be made cheaply and in large quantities. If we can improve the efficiency somewhat, we may be able to make a real difference in meeting energy needs in the future.”

“That’s why we’ve christened the new paint, Sun-Believable,” he adds.

Kamat and his team also plan to study ways to improve the stability of the new material.

NDnano is one of the leading nanotechnology centers in the world. Its mission is to study and manipulate the properties of materials and devices, as well as their interfaces with living systems, at the nano-scale.

This research was funded by the Department of Energy’s Office of Basic Energy Sciences.

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