Navigation Links
University of Minnesota researchers clear major hurdle in road to high-efficiency solar cells

A team of University of Minnesota-led researchers has cleared a major hurdle in the drive to build solar cells with potential efficiencies up to twice as high as current levels, which rarely exceed 30 percent.

By showing how energy that is now being lost from semiconductors in solar cells can be captured and transferred to electric circuits, the team has opened a new avenue for solar cell researchers seeking to build cheaper, more efficient solar energy devices. The work is published in this week's Science.

A system built on the research could also slash the cost of manufacturing solar cells by removing the need to process them at very high temperatures.

The achievement crowns six years of work begun at the university Institute of Technology (College of Science and Engineering) chemical engineering and materials science professors Eray Aydil and David Norris and chemistry professor Xiaoyang Zhu (now at the university of Texas-Austin) and spearheaded by U of M graduate student William Tisdale.

In most solar cells now in use, rays from the sun strike the uppermost layer of the cells, which is made of a crystalline semiconductor substanceusually silicon. The problem is that many electrons in the silicon absorb excess amounts of solar energy and radiate that energy away as heat before it can be harnessed.

An early step in harnessing that energy is to transfer these "hot" electrons out of the semiconductor and into a wire, or electric circuit, before they can cool off. But efforts to extract hot electrons from traditional silicon semiconductors have not succeeded.

However, when semiconductors are constructed in small pieces only a few nanometers wide -- "quantum dots" -- their properties change.

"Theory says that quantum dots should slow the loss of energy as heat," said Tisdale. "And a 2008 paper from the University of Chicago showed this to be true. The big question for us was whether we could also speed up the extraction and transfer of hot electrons enough to grab them before they cooled. "

In the current work, Tisdale and his colleagues demonstrated that quantum dotsmade not of silicon but of another semiconductor called lead selenide -- could indeed be made to surrender their "hot" electrons before they cooled. The electrons were pulled away by titanium dioxide, another common inexpensive and abundant semiconductor material that behaves like a wire.

"This is a very promising result," said Tisdale. "We've shown that you can pull hot electrons out very quickly before they lose their energy. This is exciting fundamental science."

The work shows that the potential for building solar cells with efficiencies approaching 66 percent exists, according to Aydil.

"This work is a necessary but not sufficient step for building very high-efficiency solar cells," he said. "It provides a motivation for researchers to work on quantum dots and solar cells based on quantum dots."

The next step is to construct solar cells with quantum dots and study them. But one big problem still remains: "Hot" electrons also lose their energy in titanium dioxide. New solar cell designs will be needed to eliminate this loss, the researchers said.

Still, "I'm comfortable saying that electricity from solar cells is going to be a large fraction of our energy supply in the future," Aydil noted.


Contact: Preston Smith
University of Minnesota

Related biology technology :

1. Sustainable Technology Company Cerealus and University of Maine Issued Patent for "Barrier Compositions and Articles"
2. Diversity Publication Names University Hospitals One of Top Hospital Systems in the Nation
3. Ben-Gurion University students develop device to help blind manuever
4. Hat-trick for University of Montreal scientists
5. University of Maryland School of Pharmacy Adopts BioSoteria's eLearning Drug Safety Courses
6. Colorado State University student awarded top student prize in laser research
7. Elekta / Mitsubishi Electric Collaboration Helps Japans Gunma University Heavy Ion Medical Center Launch Advanced Carbon Ion Therapy for Treating Cancer
8. The iBridge Network Adds Torontos University Health Network as First Canadian Partner
9. Zymes LLC, University of Windsor and National Research Council of Canada Collaborative Research Presented at the 2010 Experimental Biology Meeting in Anaheim, California
10. Vanderbilt University Hospital Selects Allscripts Care Management
11. RAPS Partners With Chinese University to Develop Regulatory Courses
Post Your Comments:
Related Image:
University of Minnesota researchers clear major hurdle in road to high-efficiency solar cells
(Date:11/24/2015)... -- Cepheid (NASDAQ: CPHD ) today announced that ... and invited investors to participate via webcast. ... 1, 2015 at 11.00 a.m. Eastern Time --> ... 1, 2015 at 11.00 a.m. Eastern Time --> ... NY      Tuesday, December 1, 2015 at 11.00 ...
(Date:11/24/2015)... Nov. 24, 2015 /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ: ... on behalf of the Toronto Stock Exchange, confirms that ... are no corporate developments that would cause the recent ... --> --> About Aeterna Zentaris Inc. ... --> Aeterna Zentaris is a specialty biopharmaceutical ...
(Date:11/24/2015)... November 24, 2015 SHPG ) announced today ... the Piper Jaffray 27 th Annual Healthcare Conference in ... 2015, at 8:30 a.m. EST (1:30 p.m. GMT). --> ... Officer, will participate in the Piper Jaffray 27 th Annual ... on Tuesday, December 1, 2015, at 8:30 a.m. EST (1:30 p.m. ...
(Date:11/24/2015)... ... November 24, 2015 , ... In harsh industrial ... points for in-line sensors can represent a weak spot where leaking process media ... of retractable sensor housings , which are designed to tolerate extreme process conditions. ...
Breaking Biology Technology:
(Date:11/10/2015)... Nov. 10, 2015  In this report, ... basis of product, type, application, disease indication, ... this report are consumables, services, software. The ... safety biomarkers, efficacy biomarkers, and validation biomarkers. ... are diagnostics development, drug discovery and development, ...
(Date:11/9/2015)... 2015 ... "Global Law Enforcement Biometrics Market 2015-2019" ... ) has announced the addition ... Market 2015-2019" report to their offering. ... ) has announced the addition of ...
(Date:11/4/2015)... , November 4, 2015 ... market report published by Transparency Market Research "Home Security Solutions ... and Forecast 2015 - 2022", the global home security solutions ... bn by 2022. The market is estimated to expand ... from 2015 to 2022. Rising security needs among customers ...
Breaking Biology News(10 mins):