Quantum dots with built-in charge boost solar cell efficiency by 50%

Published: 16 May 2011 y., Monday

For the past few years, researchers have been using quantum dots to increase the light absorption and overall efficiency of solar cells. 

The researchers, Kimberly Sablon and John W. Little (US Army Research Laboratory in Adelphi, Maryland), Vladimir Mitin, Andrei Sergeev, and Nizami Vagidov (University of Buffalo in Buffalo, New York), and Kitt Reinhardt (AFOSR/NE in Arlington, Virginia) have published their study on the increased solar cell efficiency in a recent issue of Nano Letters.

In their study, the researchers studied heterostructure solar cells with InAs/GaAs quantum dots. As photovoltaic materials, the quantum dots allow for harvesting of the infrared radiation to convert it into electric energy. However, the quantum dots also enhance the recombination of photocarriers and decrease the photocurrent. For this reason, up to now the improvement of photovoltaic efficiency due to quantum dots has been limited by several percent.

Here, the researchers have proposed to charge quantum dots by using selective interdot doping. In their experiments, the researchers compared doping levels of 2, 3, and 6 additional electrons per quantum dot, which resulted in photovoltaic efficiency increases of 4.5%, 30%, and 50%, respectively, compared to an undoped solar cell. For the 6-electron doping level, that 50% increase corresponds to an overall efficiency increase from 9.3% (for undoped solar cells) to 14%.

The researchers attributed this radical improvement of the photovoltaic efficiency to two basic effects. First, the built-in-dot charge induces various transitions of the electrons and enhances harvesting of the infrared radiation. Second, the built-in-dot charge creates potential barriers around dots and these barriers suppress capture processes for electrons and do not allow them to return back into the dots.

In addition, the researchers predict that further increasing the doping level will lead to an even stronger efficiency enhancement, since there was no evidence of saturation. In the future, the researchers plan to further investigate how these effects influence each other at higher doping levels. They predict that further increasing the doping level and radiation intensity will lead to an even stronger efficiency enhancement, since there was no evidence of saturation.

Šaltinis: physorg.com
Copying, publishing, announcing any information from the News.lt portal without written permission of News.lt editorial office is prohibited.

Facebook Comments

New comment


Captcha

Associated articles

Related videos

05/02/2014

Padėkime augti

Nokia offers augmented reality job search

Mobile phone giant Nokia is enlisting Britain’s young entrepreneurs to build new businesses using its career services app, JobLens. Launched in June, JobLens is a Windows Phone 8 app that helps users search for jobs in their local area. more »

Antarctic ice-flow map reveals clues to climate change

A new map of Antarctica illustrates for the first time how ice moves across the continent. more »

Experimental plane reaches 13,000 mph

The US Department of Defense's innovations arm, known as DARPA, has released test-flight video of its experimental hypersonic aircraft travelling at a speed of Mach 20, about 13,000 miles per hour. more »

Scientists develop new weapon against bird-strike at airports

New Zealand scientists have developed a designed to reduce the number of bird strikes at airports. more »

Taiwanese researchers introduce first erasable electronic paper

Taiwanese researchers are taking recycling to a new level with "i2r e-Paper", a rewritable electronic paper that can be re-used up to 260 times. The developers say their e-paper will soon replace the conventional paper used for signs and posters. more »

Wireless car technology promises charge-free future for motorists

Wireless car technology promises charge-free future for motorists While electric-powered cars are rapidly gaining momentum as a viable alternative to conventional petrol-driven vehicles, there are now moves afoot to produce cars that can be charged wirelessly. The technology behind wireless electric cars could herald an idyllic future for motorists in which they can drive as far as they like without ever worrying about recharging. more »

Transplant patient takes heart from pioneering surgery

A British man is preparing to leave hospital after pioneering surgery to install an artificial heart implant. The implant is powered by a portable driver worn in a shoulder bag and is designed to keep Matthew Green alive while he waits for a heart transplant. more »

20 million year-old fossil found

A twenty million year-old fossil, thought to be from a distant cousin of modern apes, is discovered in Uganda. more »

Virtual reality helps ready surgeons for the operating

Forget scrubbing up, a new virtual surgery simulator uses the latest computer technology to train surgeons for laproscopic surgery, dramatically decreasing the need for practice on human patients. more »

Scientists warn of Planet of the Apes science

A group of British scientists have expressed concerns that experiments on primates could give rise to a 'Planet of the Apes' type scenario. more »