news digest ♦ Solar
Since 2001 Emcore solar cells or panels have supplied primary power to over 130 successful space missions with zero on-orbit failures. The Company’s proven manufacturing capability, technology leadership and unsurpassed reliability make Emcore the supplier of choice for demanding space programs
Magnolia is applying nanotechnology to boost solar cell performance
Nano-structured coatings to cut reflection losses and trap more light in CIGS and III-V cells
Magnolia Solar has announced that it is pioneering the application of nanotechnology for both flexible CIGS and III-V solar cells in order to boost performance and lower costs, using nano-structured optical coatings that can minimise reflection losses and enhance light trapping.
The US company also says it is developing a way to apply novel nano structured designs to the absorber layer of high-performance III-V and CIGS solar cells in order to reduce recombination losses and increase the capture of low-energy photons.
“Emerging technical approaches for achieving flexible photovoltaic power include the growth of copper indium gallium diselenide (CIGS) cells on flexible substrates and the epitaxial liftoff (ELO) of III-V devices onto thin metal film,” said Roger Welser, Magnolia’s CTO.
The company is working closely with the newly merged SUNY College of Nanoscale Science and Engineering (CNSE) / SUNY Institute of Technology (SUNYIT) institution. “Our office in the Albany NanoTech complex allows our technical staff to work very closely with top researchers at the CNSE/SUNYIT facilities which have directly led to innovative patent pending designs using nanotechnology. This is helping us to meet our goals of high-efficiency thin film solar cells,” said Ashok K. Sood, president and CEO of Magnolia Solar Corporation
Based in Albany, NY and Woburn MA, Magnolia is targeting a variety of civilian and defense applications for its photovoltaic solar cells.
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www.compoundsemiconductor.net Issue VI 2014
Quantum dots boost conversion efficiency of GaAs Solar cells Dots act as luminescent downshifters
A team of scientists from Taiwan has shown that adding CdS or CdSe quantum dots (QDs) to GaAs solar cells could increase their efficiency by nearly 25 percent. The results were reported in Nature last week.
GaAs-based single-junction solar cells already hold the photovoltaic world record for the highest power conversion efficiency (PCE) at 28.8 percent. Boosting conversion efficiency in GaAs solar cells further requires reducing surface reflection and using the full solar spectrum, especially in the ultraviolet (UV) range.
High-energy photons can be easily absorbed at short distances, but the generated electron-hole pairs are close to the semiconductor surface, where recombination loss is strong. One way of solving this is to find a way to transform high-energy photons into lower-energy photons in process called luminescent downshifting.
Organic dyes have previously been used as downshifters but dye molecules have poor photon stability and narrow absorption spectrum bands. The researchers from National Chiao Tung University and the Industrial Technology Research Institute, in Hsinchu, Taiwan, used various QDs as the downshifting agents. The resultant hybrid design offers antireflective features to boost photon harvesting at long wavelengths while enhancing the collection of photogenerated carriers in the ultraviolet region.
They measured and analysed several photovoltaic parameters, including short-circuit current density, open circuit voltage, and external quantum efficiency to investigate the performance of the hybrid device. The results, they say, showed that
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