Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Nanopillars Promise Cheap, Efficient, Flexible Solar Cells

An aluminum substrate forms a template for a forest of cadmium sulfide nanopillars and also serves as a bottom electrode. Embedded in clear cadmium telluride and equipped with a top electrode of copper and gold, the result is an inexpensive and efficient 3-D solar cell.
An aluminum substrate forms a template for a forest of cadmium sulfide nanopillars and also serves as a bottom electrode. Embedded in clear cadmium telluride and equipped with a top electrode of copper and gold, the result is an inexpensive and efficient 3-D solar cell.

Abstract:
Researchers at the U.S. Department of Energy's Lawrence Berkeley National Laboratory and the University of California at Berkeley have demonstrated a way to fabricate efficient solar cells from low-cost and flexible materials. The new design grows optically active semiconductors in arrays of nanoscale pillars, each a single crystal, with dimensions measured in billionths of a meter.

Nanopillars Promise Cheap, Efficient, Flexible Solar Cells

Berkeley, CA | Posted on July 9th, 2009

"To take advantage of abundant solar energy we have to find ways to mass-produce efficient photovoltaics," says Ali Javey, a faculty scientist in Berkeley Lab's Materials Sciences Division and a professor of electrical engineering and computer science at UC Berkeley. "Single-crystalline semiconductors offer a lot of promise, but standard ways of making them aren't economical."

A solar cell's basic job is to convert light energy into charge-carrying electrons and "holes" (the absence of an electron), which flow to electrodes to produce a current. Unlike a typical two-dimensional solar cell, a nanopillar array offers much more surface for collecting light. Computer simulations have indicated that, compared to flat surfaces, nanopillar semiconductor arrays should be more sensitive to light, have a greatly enhanced ability to separate electrons from holes, and be a more efficient collector of these charge carriers.

"Unfortunately, early attempts to make photovoltaic cells based on pillar-shaped semiconductors grown from the bottom up yielded disappointing results. Light-to-electricity efficiencies were less than one to two percent," says Javey. "Epitaxial growth on single crystalline substrates was often used, which is costly. The nanopillar dimensions weren't well controlled, pillar density and alignment was poor, and the quality of the interface between the semiconductors was poor."

Javey devised a new, controlled way to use a method called the "vapor-liquid-solid" process to make large-scale modules of dense, highly ordered arrays of single-crystal nanopillars. Inside a quartz furnace his group grew pillars of electron-rich cadmium sulfide on aluminum foil, in which geometrically distributed pores made by anodization served as a template.

n the same furnace they submerged the nanopillars, once grown, in a thin layer of hole-rich cadmium telluride, which acted as a window to collect the light. The two materials in contact with each other form a solar cell in which the electrons flow through the nanopillars to the aluminum contact below, and the holes are conducted to thin copper-gold electrodes placed on the surface of the window above.

The efficiency of the test device was measured at six percent, which while less than the 10 to 18 percent range of mass-produced commercial cells is higher than most photovoltaic devices based on nanostructured materials - even though the nontransparent copper-gold electrodes on top of the Javey group's test device cut its efficiency by 50 percent. In future, top contact transparency can easily be improved.

Other factors that greatly affect the efficiency of a 3-D nanopillar-array solar cell include its density and the exposed length of the pillars in contact with the window material. These dimensions are easily optimized in future generations of the device.

Concerned with practical applications as well as theoretical performance, the researchers made a flexible solar cell of the same design by etching away the aluminum substrate and substituting a thin layer of indium for the bottom electrode. They sheathed the whole solar cell in clear plastic (polydimethylsiloxane) to make a bendable device, which could be flexed with only marginal effect on performance - and no degradation of performance after repeated bending.

"There are lots of ways to improve 3-D nanopillar photovoltaics for higher performance, and ways to simplify the fabrication process as well, but the method is already hugely promising as a way to lower the cost of efficient solar cells," says Javey. "There's the ability to grow single-crystalline structures directly on large aluminum sheets. And the 3-D configuration means the requirements for quality and purity of the input materials are less stringent and less costly. Nanopillar arrays are a new path to versatile solar modules."

"Three-dimensional nanopillar-array photovoltaics on low-cost and flexible substrates," by Zhiyong Fan, Haleh Razavi, Jae-won Do, Aimee Moriwaki, Onur Ergen, Yu-Lun Chueh, Paul W. Leu, Johhny C. Ho, Toshitake Takahashi, Lothar A. Reichertz, Steven Neale, Kyoungsik Yu, Ming Wu, Joel W. Ager, and Ali Javey, appears in the August issue of Nature Materials and is available in advance online publication at www.nature.com/nmat/journal/vaop/ncurrent/abs/nmat2493.html.

This work was supported in part by the Helios Solar Energy Research Center, which is supported by the U.S. Department of Energy's Office of Science, Office of Basic Energy Sciences.

####

About Berkeley Lab
Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California.

For more information, please click here

Contacts:
Paul Preuss
(510) 486-6249

Copyright © Berkeley Lab

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Deep Space Industries and SFL selected to provide satellites for HawkEye 360’s Pathfinder mission: The privately-funded space-based global wireless signal monitoring system will be developed by Deep Space Industries and UTIAS Space Flight Laboratory May 26th, 2016

Laboratories

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

ORNL demonstrates large-scale technique to produce quantum dots May 21st, 2016

Scientists take a major leap toward a 'perfect' quantum metamaterial: Berkeley Lab, UC Berkeley researchers lead study that uses trapped atoms in an artificial crystal of light May 13th, 2016

Atomic force microscope reveals molecular ghosts: Mapping molecules with atomic precision expands toolbox for designing new catalytic reactions May 11th, 2016

Govt.-Legislation/Regulation/Funding/Policy

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Harnessing solar and wind energy in one device could power the 'Internet of Things' May 26th, 2016

Thermal modification of wood and a complex study of its properties by magnetic resonance May 26th, 2016

Discoveries

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Finding a new formula for concrete: Researchers look to bones and shells as blueprints for stronger, more durable concrete May 26th, 2016

Announcements

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Deep Space Industries and SFL selected to provide satellites for HawkEye 360’s Pathfinder mission: The privately-funded space-based global wireless signal monitoring system will be developed by Deep Space Industries and UTIAS Space Flight Laboratory May 26th, 2016

Energy

Harnessing solar and wind energy in one device could power the 'Internet of Things' May 26th, 2016

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Light can 'heal' defects in new solar cell materials: Defects in some new electronic materials can be removed by making ions move under illumination May 24th, 2016

Technique improves the efficacy of fuel cells: Research demonstrates a new phase transition from metal to ionic conductor May 18th, 2016

Solar/Photovoltaic

Harnessing solar and wind energy in one device could power the 'Internet of Things' May 26th, 2016

Light can 'heal' defects in new solar cell materials: Defects in some new electronic materials can be removed by making ions move under illumination May 24th, 2016

This 'nanocavity' may improve ultrathin solar panels, video cameras and more May 16th, 2016

New research shows how silver could be the key to gold-standard flexible gadgets: Silver nanowires are an ideal material for current and future flexible touch-screen technologies May 13th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic