Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Solar cells: Powered by nanoholes

07.07.2014

A simple and inexpensive fabrication procedure boosts the light-capturing capabilities of tiny holes carved into silicon wafers.

Increasing the cost-effectiveness of photovoltaic devices is critical to making these renewable energy sources competitive with traditional fossil fuels. One possibility is to use hybrid solar cells that combine silicon nanowires with low-cost, photoresponsive polymers.


A straightforward procedure that transforms silver nanospheres (top) into silicon nanoholes (bottom) can overcome the shortcomings of nanowire-based solar cells

Reproduced, with permission, from Ref.1 © 2014 American Institute of Physics

The high surface area and confined nature of nanowires allows them to trap significant amounts of light for solar cell operations. Unfortunately, these thin, needle-like structures are very fragile and tend to stick together when the wires become too long.

Now, findings by Xincai Wang from the A*STAR Singapore Institute of Manufacturing Technology and co-workers from Nanyang Technological University could turn the tables on silicon nanowires by improving the manufacturing of silicon ‘nanoholes’ — narrow cavities carved into silicon wafers that have enhanced mechanical and light-harvesting capabilities(1).

Nanoholes are particularly effective at capturing light because photons can ricochet many times inside these openings until absorption occurs. Yet a practical understanding of how to fabricate these tiny structures is still lacking. One significant problem, notes Wang, is control of the initial stages of nanohole formation — a crucial period that can often induce defects into the solar cell.

Instead of traditional time-consuming lithography, the researchers identified a rapid, ‘maskless’ approach to producing nanoholes using silver nanoparticles. First, they deposited a nanometre-thin layer of silver onto a silicon wafer which they toughened by annealing it using a rapid-burst ultraviolet laser. Careful optimization of this procedure yielded regular arrays of silver nanospheres on top of the silicon surface, with sphere size and distribution controlled by the laser annealing conditions.

Next, the nanosphere–silicon complex was immersed into a solution of hydrogen peroxide and hydrofluoric acid — a mixture that eats away at silicon atoms directly underneath the catalytic silver nanospheres. Subsequent removal of the silver particles with acid produced the final, nanohole-infused silicon surface (see image).

The team analyzed the solar cell activity of their nanohole interfaces by coating them with a semiconducting polymer and metal electrodes. Their experiments revealed a remarkable dependence on nanohole depth: cavities deeper than one micrometer showed sharp drops in power conversion efficiency from a maximum of 8.3 per cent due to light scattering off of rougher surfaces and higher series resistance effects.

“Our simple process for making hybrid silicon nanohole devices can successfully reduce the fabrication costs which impede the solar cell industry,” says Wang. “In addition, this approach can be easily transferred to silicon thin films to develop thin-film silicon–polymer hybrid solar cells with even higher efficiency.”

Reference

1. Hong, L., Wang, X., Zheng, H., He, L., Wang, H., Yu, H. & Rusli, E. High efficiency silicon nanohole/organic heterojunction hybrid solar cell. Applied Physics Letters 104, 053104 (2014). 

Associated links

http://www.research.a-star.edu.sg/research/6996

Lee Swee Heng | Research SEA News
Further information:
http://www.researchsea.com

More articles from Power and Electrical Engineering:

nachricht Engineer Improves Rechargeable Batteries with MoS2 Nano 'Sandwich'
17.04.2015 | Kansas State University

nachricht Packing Heat: New Fluid Makes Untapped Geothermal Energy Cleaner
17.04.2015 | Pacific Northwest National Laboratory

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Advances in Molecular Electronics: Lights On – Molecule On

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the University of Konstanz are working on storing and processing information on the level of single molecules to create the smallest possible components that will combine autonomously to form a circuit. As recently reported in the academic journal Advanced Science, the researchers can switch on the current flow through a single molecule for the first time with the help of light.

Dr. Artur Erbe, physicist at the HZDR, is convinced that in the future molecular electronics will open the door for novel and increasingly smaller – while also...

Im Focus: Pruning of Blood Vessels: Cells Can Fuse With Themselves

Cells of the vascular system of vertebrates can fuse with themselves. This process, which occurs when a blood vessel is no longer necessary and pruned, has now been described on the cellular level by Prof. Markus Affolter from the Biozentrum of the University of Basel. The findings of this study have been published in the journal “PLoS Biology”.

The vascular system is the supply network of the human organism and delivers oxygen and nutrients to the last corners of the body. So far, research on the...

Im Focus: Astronomers reveal supermassive black hole's intense magnetic field

Astronomers from Chalmers University of Technology have used the giant telescope Alma to reveal an extremely powerful magnetic field very close to a supermassive black hole in a distant galaxy

Astronomers from Chalmers University of Technology have used the giant telescope Alma to reveal an extremely powerful magnetic field very close to a...

Im Focus: A “pin ball machine” for atoms and photons

A team of physicists from MPQ, Caltech, and ICFO proposes the combination of nano-photonics with ultracold atoms for simulating quantum many-body systems and creating new states of matter.

Ultracold atoms in the so-called optical lattices, that are generated by crosswise superposition of laser beams, have been proven to be one of the most...

Im Focus: UV light robot to clean hospital rooms could help stop spread of 'superbugs'

Can a robot clean a hospital room just as well as a person?

According to new research out of the Texas A&M Health Science Center College of Medicine, that is indeed the case. Chetan Jinadatha, M.D., M.P.H., assistant...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

HHL's Entrepreneurship Conference on FinTech

13.04.2015 | Event News

World Conference On Regenerative Medicine 2015: Registration And Abstract Submission Now Open

25.03.2015 | Event News

University presidents from all over the world meet in Hamburg

19.03.2015 | Event News

 
Latest News

High-Power Laser Spinoff Proves Versatility Is Strength

20.04.2015 | Physics and Astronomy

New “Cool Roof Time Machine” Will Accelerate Cool Roof Deployment

20.04.2015 | Architecture and Construction

STAR Heavy Flavor Tracker Detects Signs of Charm at RHIC

20.04.2015 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>