NREL, UCLA certify world record for polymer solar cell efficiency

Mar 05, 2012

Scientists boosted the significance of tandem polymer solar cells by successfully testing cells with low-bandgap polymers that achieved certified conversion efficiencies of 8.62 ± 0.3% with respect to standard terrestrial reporting conditions.

That’s the highest independently measured efficiency for a polymer solar cell, say researchers from the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) and UCLA, who co-authored a report in the Feb. 12 issue of Nature Photonics.

That report, “Tandem polymer featuring a spectrally matched low-bandgap polymer,” notes that tandem solar cells by their design can harvest a broader of the sun’s rays than single solar cells. But polymer solar cells have lagged because it’s been difficult finding a suitable low-bandgap polymer.”

In sophisticated tests, the researchers were able to demonstrate highly efficient single and tandem featuring a low-bandgap conjugated polymer (PBDTT-DPP: bandgap, 1.44 eV). When they tested a single-layer device with the polymer it converted the sun’s rays into electricity at an efficiency of about 6%. When the polymer was applied to tandem solar cells, the power conversion efficiency reached 8.62%.

The UCLA group recently improved on this result by incorporating a new infrared-absorbing from Sumitomo Chemical in Japan. NREL measured the power conversion efficiency at 10.6+/-0.3% under standard terrestrial reporting conditions.

Stacking layers of different materials in a solar cell means multiple bandgaps, each of which captures a different part of the solar spectrum. The challenge is to achieve a high current by efficiently using the low-energy portion of the solar spectrum, and achieving a small energy bandgap – less than 1.5 eV.

The successful test took place in NREL’s Spectrolab X-25 solar simulator, also called the One-Sun Solar Simulator, which has wide current and voltage ranges.

“Accurately measuring tandem cells is difficult. The NREL simulator provide unparalleled accuracy by precisely adjusting the spectrum, and did so in a fraction of the time that other simulators could do the job,” said NREL Principal Engineer Keith Emery. Each device junction must behave the same under the simulator spectrum as it would under the reference spectrum. It requires significant adjustment of the simulator spectrum, normally a very tedious process.

NREL’s One-Sun Solar Simulator was able to turn an ordeal that typically takes all day into a five-minute task. “We think it’s also more accurate because we can better adjust the spectrum,” Emery said.

Explore further: New battery technology for electric vehicles

Provided by National Renewable Energy Laboratory

5 /5 (1 vote)
add to favorites email to friend print save as pdf

Related Stories

Device can heat home, save money

Apr 19, 2011

(PhysOrg.com) -- A new polymer-based solar-thermal device is the first to generate power from both heat and visible sunlight – an advance that could shave the cost of heating a home by as much as 40 percent.

Recommended for you

New battery technology for electric vehicles

Nov 21, 2014

Scientists at the Canadian Light Source are on the forefront of battery technology using cheaper materials with higher energy and better recharging rates that make them ideal for electric vehicles (EVs).

Company powers up with food waste

Nov 19, 2014

Garden products company Richgro is using Western Australian food waste to power their operations in a new zero-waste system.

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

CapitalismPrevails
1 / 5 (1) Mar 09, 2012
.3% increase in efficiency seems very low to me.
kaasinees
1 / 5 (1) Mar 09, 2012
.3% increase in efficiency seems very low to me.

10.6±0.3% - 8.62 ± 0.3% = 1.98 ± 0.3%

not .3%

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.