Navigation Links
Zinc oxide gives green shine to new photoconductors

Photodetectors -- devices found in cell phones, digital cameras and other consumer gadgets that utilize photoconducting materials -- are a green technology in performance (converting light into electricity), but the manufacture of very powerful photodetectors needs to be improved before they can qualify for solid green status.

This is especially true if photoconducting materials are to be widely used for producing solar energy.

Northwestern University researchers have designed a high-performing photoconducting material that uses zinc oxide -- an environmentally friendly inorganic compound found in baby powder and suntan lotion -- instead of lead sulfide. (Currently, the best performing photoconductor is based on lead sulfide nanoparticles.)

The new material converts light into electricity but, unlike conventional materials, also features a novel combination of attractive attributes: environmentally benign chemistry, low-cost production, a high level of detectivity, mechanical flexibility and wavelength tunability (ability to design the material to absorb the most important part of the solar spectrum).

This impressive package of features holds promise for the material's use in large-area photovoltaic solar cells as well as flexible electronics -- even in clothing and newspapers. Conventional photoconducting materials are expensive to manufacture, making them unsuitable for widespread solar energy use, and they are rigid, making them unsuitable for flexible electronics.

Features of the new hybrid material and its synthesis are detailed in a study published by the journal Nature Materials.

"One property of our hybrid material that is especially important for solar-energy devices is its high level of detectivity -- less light is needed to get a good strong and clear signal," said lead researcher Samuel I. Stupp, Board of Trustees Professor of Materials Science and Engineering, Chemistry and Medicine at Northwestern. "This comes from the material's highly ordered architecture, which helps transport the electrons efficiently."

The material has a detectivity level comparable to amorphous silicon, which is widely used in large-area electronics applications, such as liquid-crystal displays (LCDs).

Stupp and his research team designed a novel nanoscale architecture that places the inorganic component (zinc oxide) right next to the organic component, with this pattern alternating over and over, like pages in a book. The pages are packed very tightly.

Each organic page -- which can be one of thousands of different types of molecules -- absorbs light, and an electron is transferred directly to the zinc oxide page, generating current. This works -- and works extremely efficiently -- because the organic and inorganic components are so close together.

To build a book, the researchers grow a precursor material to zinc oxide in the presence of self-assembling organic molecules. (The material can be grown on any metallic or conducting substrate.) The precursor, zinc hydroxide, is formed using electrodeposition and then thermally converted to zinc oxide. Each zinc oxide page is a nanometer thick while the organic page is one to two nanometers thick, depending on the molecule being used.

In the Nature Materials paper the researchers demonstrate that they can build orderly books with high detectivity. But in order for their materials to be used for solar energy, Stupp says, they must build entire "macroscopic libraries" of these books. And, like the books, the libraries must be highly ordered.

"Right now our library is a little disordered, but we are working on optimizing our materials for use in solar energy devices," said Stupp, director of the Institute for BioNanotechnology in Medicine at Northwestern.


Contact: Megan Fellman
Northwestern University

Related biology technology :

1. Gold-palladium nanoparticles achieve greener, smarter production of hydrogen peroxide
2. New small-scale generator produces alternating current by stretching zinc oxide wires
3. Particle Sciences sells T-COTE(R) Line of Microfine Titanium Dioxides to Sensient
4. New graphene-based material clarifies graphite oxide chemistry
5. ActivBiotics Receives FDA Orphan Drug Designation for Superoxide Dismutase Mimetic, M40403, in Oral Mucositis of Cancer
6. Chemists measure copper levels in zinc oxide nanowires
7. National Association of Emergency Medical Technicians (NAEMT) Supports Prehospital Screening for Carbon Monoxide in the Blood
8. International Association of Fire Fighters (IAFF) Advocates Screening Fire Fighters for Carbon Monoxide Poisoning Using Pulse CO-Oximetry
9. PharmaNet Development Group Gives Notice of Anticipated Fundamental Change and Merger to Holders of Its Convertible Notes
10. M2S Expert gives address "Applying the Principles of Six Sigma in the Imaging Core Lab" at Imaging for Clinical Trials conference
11. New Health Retreat Gives a Fresh Attitude Towards Disease Prevention
Post Your Comments:
(Date:10/13/2015)... , ... October 13, 2015 , ... ... recombinant antibodies, today announced that it has received a Phase I Small Business ... by the National Institute of General Medical Sciences (NIGMS), will fund the development ...
(Date:10/13/2015)... , October 13, 2015 ... and development company, has entered into a strategic relationship ... and Paris, France ... --> --> This collaborative arrangement gives ... respected scientific advisory team as well as long established ...
(Date:10/13/2015)... , Oct. 13, 2015  According to Kalorama ... will reach $102 billion by the end of ... the health industry, as it is estimated that ... of laboratory tests. In addition to diagnosing patients, ... evaluate disease progression, monitor drug treatment and conditions, ...
(Date:10/13/2015)... ... October 13, 2015 , ... ... of automation systems, material handling solutions and components, is opening its latest Parker ... State Street, the facility is Exotic’s second major expansion in Metropolitan Detroit in ...
Breaking Biology Technology:
(Date:10/8/2015)... Oktober 2015 Die Track Group, ... des Bereiches Tracking, hat heute bekannt gegeben, ... Virginias (Department of Corrections – DOC) unterzeichnet ... alle Strafen geliefert werden, die der Behörde ... für den Amerikanischen Kontinent der Track Group. ...
(Date:10/6/2015)... 2015 Track Group, Inc. (OTCQX: TRCK), a ... signed a contract with the Virginia Department of Corrections ... of sentences under the Department,s oversight. Derek ... contract with the Virginia DOC will expand our footprint ... our position as a trusted leader in offender electronic ...
(Date:10/1/2015)... Oct. 1, 2015  Biometrics includes diverse set ... body characteristics, such as fingerprints, eye retinas, facial ... of biometrics technology has been constantly increasing in ... five years. In addition to the most prominent ... recognition, other means of biometric authentication are rapidly ...
Breaking Biology News(10 mins):