UCLA Engineers Pioneer Affordable Alternative Energy: Solar Energy Cells Made Of Everyday Plastic

In research published today in Nature Materials magazine, UCLAengineering professor Yang Yang, postdoctoral researcher Gang Li andgraduate student Vishal Shrotriya showcase their work on an innovativenew plastic (or polymer) solar cell they hope eventually can beproduced at a mere 10 percent to 20 percent of the current cost oftraditional cells, making the technology more widely available.

"Solar energy is a clean alternative energy source. It'sclear, given the current energy crisis, that we need to embrace newsources of renewable energy that are good for our planet. I believevery strongly in using technology to provide affordable options thatall consumers can put into practice," Yang said.

The price for quality traditional solar modules typically isaround three to four times more expensive than fossil fuel. Whileprices have dropped since the early 1980s, the solar module itselfstill represents nearly half of the total installed cost of atraditional solar energy system.

Currently, nearly 90 percent of solar cells in the world aremade from a refined, highly purified form of silicon -- the samematerial used in manufacturing integrated circuits and computer chips.High demand from the computer industry has sharply reduced theavailability of quality silicon, resulting in prohibitively high coststhat rule out solar energy as an option for the average consumer.

Made of a single layer of plastic sandwiched between twoconductive electrodes, UCLA's solar cell is easy to mass-produce andcosts much less to make -- roughly one-third of the cost of traditionalsilicon solar technology. The polymers used in its construction arecommercially available in such large quantities that Yang hopescost-conscious consumers worldwide will quickly adopt the technology.

Independent tests on the UCLA solar cell already have receivedhigh marks. The nation's only authoritative certification organizationfor solar technology, the National Renewable Energy Laboratory (NREL),located in Golden, Colo., has helped the UCLA team ensure the accuracyof their efficiency numbers. The efficiency of the cell is thepercentage of energy the solar cell gathers from the total amount ofenergy, or sunshine, that actually hits it.

According to Yang, the 4.4 percent efficiency achieved by UCLA is the highest number yet published for plastic solar cells.

"As in any research, achieving precise efficiency benchmarks isa critical step," Yang said. "Particularly in this kind of research,where reported efficiency numbers can vary so widely, we're grateful tothe NREL for assisting us in confirming the accuracy of our work."

Given the strides the team already has made with thetechnology, Yang calculates he will be able to double the efficiencypercentage in a very short period of time. The target for polymer solarcell performance is ultimately about 15 percent to 20 percentefficiency, with a 15-20 year lifespan. Large-sized silicon moduleswith the same lifespan typically have a 14 percent to 18 percentefficiency rating.

The plastic solar cell is still a few years away from beingavailable to consumers, but the UCLA team is working diligently to getit to market.

"We hope that ultimately solar energy can be extensively usedin the commercial sector as well as the private sector. Imagine solarcells installed in cars to absorb solar energy to replace thetraditional use of diesel and gas. People will vie to park their carson the top level of parking garages so their cars can be charged undersunlight. Using the same principle, cell phones can also be charged bysolar energy," Yang said. "There are such a wide variety ofapplications."

About the UCLA Henry Samueli School of Engineering and Applied Science
Establishedin 1945, the UCLA Henry Samueli School of Engineering and AppliedScience offers 28 academic and professional degree programs, includingan interdepartmental graduate degree program in biomedical engineering.Ranked among the top 10 engineering schools among public universitiesnationwide, the school is home to five multimillion-dollarinterdisciplinary research centers funded by top national andprofessional agencies. For more information, visit http://www.engineer.ucla.edu/.