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:12/1/2015)... -- Twist Bioscience, a company focused on synthetic DNA, today announced ... selected as one of Foreign Policy,s 100 Leading ... of life . Each year, Foreign Policy selects ... have changed lives and are shaping the world. ... to be recognized among these incredible global leaders," said Leproust. ...
(Date:12/1/2015)... 2015 Oxford Finance LLC ("Oxford"), a specialty ... and healthcare services companies, today announced the closing of ... Inc. ("the Company"). Proceeds from the loan are being ... Company,s Rejuvaphyl™ and daily skincare products. ... brand of high potency skincare products that contain the ...
(Date:12/1/2015)... Dec. 01, 2015 ... of the "2016 Europe Cell Surface ... Technologies, Competitive Strategies, Opportunities for Suppliers--France, Germany, ... offering. --> ) has ... Europe Cell Surface Markers: Country Volume and ...
(Date:12/1/2015)... ... December 01, 2015 , ... Park Systems , ... add-on scanning ion conductance microscopy module to Park NX10 that is the only ... Park SICM benefits virtually all materials characterization that require measurements in liquid such ...
Breaking Biology Technology:
(Date:12/1/2015)... Calif. , Dec. 1, 2015 Synaptics ... human interface solutions, today announced a new agreement with ... OEMs with real-world test and development environments that combine ... solutions. The partnership reduces the complexity of FIDO certification ... software permits Synaptics and OEMs to verify FIDO enabled ...
(Date:11/30/2015)... BEACH, Fla. , Nov. 30, 2015 /PRNewswire/ ... as a finalist in this year,s Fierce Innovation Awards:  ... of FierceHealthIT , FierceHealthcare ... was recognized as a finalist in the category ... --> ...
(Date:11/26/2015)... Research and Markets ( ) has ... - Technology and Patent Infringement Risk Analysis" report ... --> Fingerprint sensors using capacitive technology represent ... sensor vendor Idex forecasts an increase of 360% of ... and of the fingerprint sensor market between 2014 and ...
Breaking Biology News(10 mins):