Welcome to DU!
The truly grassroots left-of-center political community where regular people, not algorithms, drive the discussions and set the standards.
Join the community:
Create a free account
Support DU (and get rid of ads!):
Become a Star Member
Latest Breaking News
General Discussion
The DU Lounge
All Forums
Issue Forums
Culture Forums
Alliance Forums
Region Forums
Support Forums
Help & Search
Empa scientists boost CdTe solar cell efficiency: The positive sides of doping
http://www.empa.ch/plugin/template/empa/1351/139085/---/l=2[font face=Serif][font size=5]Empa scientists boost CdTe solar cell efficiency
The positive sides of doping[/font]
13 August 2013
[font size=3]Flexible thin film solar cells that can be produced by roll-to-roll manufacturing are a highly promising route to cheap solar electricity. Now scientists from Empa, the Swiss Federal Laboratories for Materials Science and Technology, have made significant progress in paving the way for the industrialization of flexible, light-weight and low-cost cadmium telluride (CdTe) solar cells on metal foils. They succeeded in increasing their efficiency from below eight to 11.5 percent by doping the cells with copper, as they report in the current issue of “Nature Communications”.
…
One way to increase the low energy conversion efficiency of substrate CdTe cells is p-type doping of the semiconductor layer with minute amounts of metals such as copper (Cu). This would lead to an increase in the density of “holes” (positive charge carriers) as well as their lifetimes, and thus result in a high photovoltaic power, the amount of sunlight that is turned into electrical energy. A perfect idea – if CdTe weren’t so notoriously hard to dope. “People have tried to dope CdTe cells in substrate configuration before but failed time and again”, explains Ayodhya Nath Tiwari, head of Empa’s laboratory for Thin Films and Photovoltaics.
His team decided to try nonetheless using high-vacuum Cu evaporation onto the CdTe layer with a subsequent heat treatment to allow the Cu atoms to penetrate into the CdTe. They soon realized that the amount of Cu had to be painstakingly controlled: if they used too little, the efficiency wouldn’t improve much; the very same happened if they “over-doped”.
The electronic properties improved significantly, however, when Lukas Kranz, a PhD student in Tiwari’s lab, together with Christina Gretener and Julian Perrenoud fine-tuned the amount of Cu evaporation so that a mono-atomic layer of Cu would be deposited on the CdTe. “Efficiencies increased dramatically, from just under one percent to above 12”, says Kranz. Their best value was 13.6 percent for a CdTe cell grown on glass; on metal foils Tiwari’s team reached efficiencies up to 11.5 percent.
…[/font][/font]
http://dx.doi.org/10.1038/ncomms3306The positive sides of doping[/font]
13 August 2013
[font size=3]Flexible thin film solar cells that can be produced by roll-to-roll manufacturing are a highly promising route to cheap solar electricity. Now scientists from Empa, the Swiss Federal Laboratories for Materials Science and Technology, have made significant progress in paving the way for the industrialization of flexible, light-weight and low-cost cadmium telluride (CdTe) solar cells on metal foils. They succeeded in increasing their efficiency from below eight to 11.5 percent by doping the cells with copper, as they report in the current issue of “Nature Communications”.
…
One way to increase the low energy conversion efficiency of substrate CdTe cells is p-type doping of the semiconductor layer with minute amounts of metals such as copper (Cu). This would lead to an increase in the density of “holes” (positive charge carriers) as well as their lifetimes, and thus result in a high photovoltaic power, the amount of sunlight that is turned into electrical energy. A perfect idea – if CdTe weren’t so notoriously hard to dope. “People have tried to dope CdTe cells in substrate configuration before but failed time and again”, explains Ayodhya Nath Tiwari, head of Empa’s laboratory for Thin Films and Photovoltaics.
His team decided to try nonetheless using high-vacuum Cu evaporation onto the CdTe layer with a subsequent heat treatment to allow the Cu atoms to penetrate into the CdTe. They soon realized that the amount of Cu had to be painstakingly controlled: if they used too little, the efficiency wouldn’t improve much; the very same happened if they “over-doped”.
The electronic properties improved significantly, however, when Lukas Kranz, a PhD student in Tiwari’s lab, together with Christina Gretener and Julian Perrenoud fine-tuned the amount of Cu evaporation so that a mono-atomic layer of Cu would be deposited on the CdTe. “Efficiencies increased dramatically, from just under one percent to above 12”, says Kranz. Their best value was 13.6 percent for a CdTe cell grown on glass; on metal foils Tiwari’s team reached efficiencies up to 11.5 percent.
…[/font][/font]