A type of nanostructure increases the efficiency of electricity-producing photovoltaic

June 08, 2016

Sagrario Domínguez-Fernández, a Telecommunications engineer, has managed to increase light absorption in silicon by means of nanostructures etched onto photovoltaic cells. This increases the efficiency obtained in these electronic devices which are made of this element and which transform solar energy into electricity.

"Over 30% of the sunlight that strikes a silicon surface is reflected, which means it cannot be used in the photoelectric conversion," explained Sagrario Domínguez. "Because the nanostructures on the surface of a material have dimensions in the light wavelength range, they interfere with the surface in a particular way and allow the amount of reflected light to be modified".

Sagrario Domínguez designed and optimised structures on a nanometric scale "to try and find one that would minimise the reflectance [ability of a surface to reflect light] of the silicon in the wavelength range in which solar cells function". In their manufacturing process, she resorted to what is known as laser interference lithography which consists of applying laser radiation to a photo-sensitive material to create structures on a nanometric scale. Specifically, she used polished silicon wafers to which she gave the shape of cylindrical pillar and obtained a 77% reduction in the reflectance of this element.

Sagrario Domínguez then went on to modify the manufacturing processes to produce the nanostructures on the silicon substrates used in commercial solar cells. "These substrates have dimensions and a surface roughness that makes them, 'a priori', unsuitable for laser interference lithography processes," pointed out the researcher.

Having overcome the difficulties, she incorporated nanostructures onto solar cells following the standard processes of the photovoltaics industry. "According to the literature, this is the first time that it has been possible to manufacture periodic nanostructures; they are the ones that on the surface of a material are continuously repeated on substrates of this type, and therefore, the first standard solar cell with periodic nanostructures," pointed out the new PhD holder. The efficiency obtained is 15.56%, which is a very promising value when compared with others included in the literature".

Research at the MIT

She then went on to steer her work towards the manufacture of nanostructures for applications on a higher bandwidth, such as sensors. She managed to create nanocones of a great height in comparison with the base diameter. "These structures are presented in the literature as the best anti-reflection solution on the high bandwidth. The process to manufacture these structures is complicated and could be carried out thanks to the knowledge acquired in the first part of the thesis," explained Domínguez. She did this part of the work at the Massachusetts Institute of Technology (MIT), the American university where she did a nine-month internship.

These nanocone structures "cut the 30% silicon reflectance to values below between 4% and 0.2% depending on the wavelength range. This is the lowest value of reflectance found in the literature for periodic nanostructures," concluded Domínguez.

Elhuyar Fundazioa

Related Solar Cells Articles from Brightsurf:

Solar cells of the future
Organic solar cells are cheaper to produce and more flexible than their counterparts made of crystalline silicon, but do not offer the same level of efficiency or stability.

A blast of gas for better solar cells
Treating silicon with carbon dioxide gas in plasma processing brings simplicity and control to a key step for making solar cells.

Record efficiency for printed solar cells
A new study reports the highest efficiency ever recorded for full roll-to-roll printed perovskite solar cells.

Next gen solar cells perform better when there's a camera around
A literal ''trick of the light'' can detect imperfections in next-gen solar cells, boosting their efficiency to match that of existing silicon-based versions, researchers have found.

On the trail of organic solar cells' efficiency
Scientists at TU Dresden and Hasselt University in Belgium investigated the physical causes that limit the efficiency of novel solar cells based on organic molecular materials.

Exciting tweaks for organic solar cells
A molecular tweak has improved organic solar cell performance, bringing us closer to cheaper, efficient, and more easily manufactured photovoltaics.

For cheaper solar cells, thinner really is better
Researchers at MIT and at the National Renewable Energy Laboratory (NREL) have outlined a pathway to slashing costs further, this time by slimming down the silicon cells themselves.

Flexible thinking on silicon solar cells
Combining silicon with a highly elastic polymer backing produces solar cells that have record-breaking stretchability and high efficiency.

Perovskite solar cells get an upgrade
Rice University materials scientists find inorganic compounds quench defects in perovskite-based solar cells and expand their tolerance of light, humidity and heat.

Can solar technology kill cancer cells?
Michigan State University scientists have revealed a new way to detect and attack cancer cells using technology traditionally reserved for solar power.

Read More: Solar Cells News and Solar Cells Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.