Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
. Solar Energy News .




SOLAR DAILY
Collecting light with artificial moth eyes
by Staff Writers
Dusseldorf, Germany (SPX) Jun 20, 2014


How the "moth eye solar cell" is created, and how it collects light. Image courtesy Empa.

All over the world researchers are investigating solar cells which imitate plant photosynthesis, using sunlight and water to create synthetic fuels such as hydrogen. Empa researchers have developed such a photoelectrochemical cell, recreating a moth's eye to drastically increase its light collecting efficiency. The cell is made of cheap raw materials - iron and tungsten oxide.

Rust - iron oxide - could revolutionise solar cell technology. This usually unwanted substance can be used to make photoelectrodes which split water and generate hydrogen. Sunlight is thereby directly converted into valuable fuel rather than first being used to generate electricity.

Unfortunately, as a raw material iron oxide has its limitations. Although it is unbelievably cheap and absorbs light in exactly the wavelength region where the sun emits the most energy, it conducts electricity very poorly and must therefore be used in the form of an extremely thin film in order for the water splitting technique to work. The disadvantage of this is that these thin-films absorb too little of the sunlight shining on the cell.

Microspheres to collect the sunlight
Empa researchers Florent Boudoire and Artur Braun have now succeeded in solving this problem. A special microstructure on the photoelectrode surface literally gathers in sunlight and does not let it out again. The basis for this innovative structure are tiny particles of tungsten oxide which, because of their saturated yellow colour, can also be used for photoelectrodes.

The yellow microspheres are applied to an electrode and then covered with an extremely thin nanoscale layer of iron oxide. When external light falls on the particle it is internally reflected back and forth, till finally all the light is absorbed. All the entire energy in the beam is now available to use for splitting the water molecules.

In principle the newly conceived microstructure functions like the eye of a moth, explains Florent Boudoire. The eyes of these night active creatures need to collect as much light as possible to see in the dark, and also must reflect as little as possible to avoid detection and being eaten by their enemies. The microstructure of their eyes especially adapted to the appropriate wavelength of light. Empa's photocells take advantage of the same effect.

In order to recreate artificial moth eyes from metal oxide microspheres, Florent Boudoire sprays a sheet of glass with a suspension of plastic particles, each of which contains at its centre a drop of tungsten salt solution. The particles lie on the glass like a layer of marbles packed close to each other.

The sheet is placed in an oven and heated, the plastic material burns away and each drop of salt solution is transformed into the required tungsten oxide microsphere. The next step is to spray the new structure with an iron salt solution and once again heat it in an oven. "Capturing light" simulated on the computer

Now, one could interpret these mixing, spraying and burning processes as pure alchemy - a series of steps that is eventually successful by pure chance. However in parallel to their practical experiments, the researchers have been running calculations modelling the process on their computers and have thus been able to simulate the "capturing of light" in the tiny spheres.

The results of the simulation agree with the experimental observations, as project leader Artur Braun confirms. It is clear to see how much the tungsten oxide contributes to the photo current and how much is due to the iron oxide.

Also, the smaller the microspheres the more light which lands on the iron oxide underneath the tiny balls. As a next step the researchers plan to investigate what the effect of several layers of microspheres lying on top of each other might be. The work on moth eye solar cells is still in progress!

Florent Boudoire, Rita Toth, Jakob Heier, Artur Braun, Edwin C. Constable, "Photonic light trapping in self-organized all-oxide microspheroids impacts photoelectrochemical water splitting, Energy and Environmental Sciences."

.


Related Links
Empa - a Research Institute of the ETH Domain
All About Solar Energy at SolarDaily.com






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





SOLAR DAILY
Admirals Bank and SunPower Announce Solar Loan Funding Program
San Jose CA (SPX) Jun 19, 2014
SunPower and Admirals Bank announced a strategic relationship to provide a $200 million loan program for SunPower residential solar projects over the next two years. The partnership supports the SunPower Loan program in the U.S., expanding the financing options available to homeowners interested in owning high-efficiency SunPower solar power systems. Under the program, borrowers may ... read more


SOLAR DAILY
Genome could unlock eucalyptus potential for paper, fuel and fiber

More than just food for koalas -- eucalyptus -- a global tree for fuel and fiber

EU agrees plan to cap use of food-based biofuels

York scientists provide new insights into biomass breakdown

SOLAR DAILY
Supercomputer emulates teenager to pass 'Turing Test'

Football-playing robots eye their own cup, and beyond

New computer program aims to teach itself everything about anything

DARPA Z-Man Program Demonstrates Human Climbing Like Geckos

SOLAR DAILY
Massachusetts to host sixth U.S. lease for offshore wind energy

London signs off on 240-turbine offshore wind farm

Scotland attracts more investments to renewable energy sector

Wind turbine payback as fast as 8 months

SOLAR DAILY
Global automakers split on 'green car' strategy

Tesla gives up patents to 'open source movement'

European taxis cause chaos in app protest

Elon Musk: 'We could definitely make a flying car'

SOLAR DAILY
Coal consumption highest since 1970

Charging Portable Electronics in 10 Minutes

Funky ferroelectric properties probed with X-rays

Magnetic cooling enables efficient, 'green' refrigeration

SOLAR DAILY
Japan minister apologises for Fukushima money gaffe

Nuclear waste dump plan on Aboriginal land abandoned

AREVA awarded a contract to provide services for Kozloduy 5 and 6 VVER nuclear reactors

AREVA to provide additional modernization services for Gosgen Facility in Switzerland

SOLAR DAILY
Japan plans carbon offset scheme with India: report

How Much Energy Will the 2014 World Cup Consume?

US invests in technology to make electric grid more secure

Report Estimates Costs and Benefits of Compliance with Renewable Portfolio Standards

SOLAR DAILY
Australian natural wonders under UNESCO spotlight

Saving trees in tropics could cut emissions by one-fifth

Forest loss starves fish

For forests, an earlier spring than ever




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.