Shiny quantum dots brighten future of solar cells
A house window that doubles as a solar panel could be on the horizon, thanks to recent quantum-dot work by Los Alamos National Laboratory researchers in collaboration with scientists from University of Milano-Bicocca (UNIMIB), Italy. Their project demonstrates that superior light-emitting properties of quantum dots can be applied in solar energy by helping more efficiently harvest sunlight.
“The key accomplishment is the demonstration of large-area luminescent solar concentrators that use a new generation of specially engineered quantum dots,” said lead researcher Victor Klimov of the Center for Advanced Solar Photophysics (CASP) at Los Alamos.
Quantum dots are ultra-small bits of semiconductor matter that can be synthesized with nearly atomic precision via modern methods of colloidal chemistry. Their emission color can be tuned by simply varying their dimensions. Color tunability is combined with high emission efficiencies approaching 100 percent. These properties have recently become the basis of a new technology – quantum dot displays – employed, for example, in the newest generation of the Kindle Fire ™ e-reader.
A luminescent solar concentrator (LSC) is a photon management device, representing a slab of transparent material that contains highly efficient emitters such as dye molecules or quantum dots. Sunlight absorbed in the slab is re-radiated at longer wavelengths and guided towards the slab edge equipped with a solar cell.
Klimov explained, “The LSC serves as a light-harvesting antenna which concentrates solar radiation collected from a large area onto a much smaller solar cell, and this increases its power output.”
“LSCs are especially attractive because in addition to gains in efficiency, they can enable new interesting concepts such as photovoltaic windows that can transform house facades into large-area energy generation units,” said Sergio Brovelli, who worked at Los Alamos until 2012 and is now a faculty member at UNIMIB.
Because of highly efficient, color-tunable emission and solution processability, quantum dots are attractive materials for use in inexpensive, large-area LSCs. One challenge, however, is an overlap between emission and absorption bands in the dots, which leads to significant light losses due to the dots re-absorbing some of the light they produce.
“Giant” but still tiny, engineered dots
To overcome this problem the Los Alamos and UNIMIB researchers have developed LSCs based on quantum dots with artificially induced large separation between emission and absorption bands (called a large Stokes shift).
These “Stokes-shift” engineered quantum dots represent cadmium selenide/cadmium sulfide (CdSe/CdS) structures in which light absorption is dominated by an ultra-thick outer shell of CdS, while emission occurs from the inner core of a narrower-gap CdSe. The separation of light-absorption and light-emission functions between the two different parts of the nanostructure results in a large spectral shift of emission with respect to absorption, which greatly reduces losses to re-absorption.
To implement this concept, Los Alamos researchers created a series of thick-shell (so-called “giant”) CdSe/CdS quantum dots, which were incorporated by their Italian partners into large slabs (sized in tens of centimeters) of polymethylmethacrylate (PMMA). While being large by quantum dot standards, the active particles are still tiny – only about hundred angstroms across. For comparison, a human hair is about 500,000 angstroms wide.
“A key to the success of this project was the use of a modified industrial method of cell-casting, we developed at UNIMIB Materials Science Department” said Francesco Meinardi, professor of Physics at UNIMIB.
Spectroscopic measurements indicated virtually no losses to re-absorption on distances of tens of centimeters. Further, tests using simulated solar radiation demonstrated high photon harvesting efficiencies of approximately 10% per absorbed photon achievable in nearly transparent samples, perfectly suited for utilization as photovoltaic windows.
The Latest on: Solar-panel windows
via Google News
The Latest on: Solar-panel windows
- Mark Wright and Michelle Keegan's dream home has CCTV and solar panelson October 12, 2021 at 7:02 am
The former TOWIE star took to their joint Instagram home account on Sunday to give a tour of their mansion in its current state and gushed: 'Nearly there!' ...
- Solar Energy Glass Market To Grow With an Impressive CAGR During the Forecast Periodon October 12, 2021 at 2:04 am
Favorable government initiatives are driving the growth in Global Solar Energy Glass Market in the forecast period 2022 2026 According to TechSci Research report Solar Energy Glass Market Global ...
- Could fitting solar panels add £1,800 to the value of your house?on October 8, 2021 at 1:55 pm
Half the cost of installing solar panels can be made back when a home is sold - and green homeowners can also save £330 a year in energy bills. We explain what you need to know before going ahead.
- Solar has its limitson October 7, 2021 at 9:00 pm
Home improvement is a matter of common sense. Everyone wants a new kitchen or bathroom. Both are really expensive.
- New Pasco solar farm by Tampa Electric planned for Crystal Springson October 7, 2021 at 7:08 am
Tampa Electric Co. bought the old Palm River Dairy site in south eastern Pasco County in Crystal Springs for $7.6 million just weeks after the county approved using the land to construct solar panels ...
- Solar panels could add nearly £2,000 to house priceson October 7, 2021 at 2:23 am
Installing solar panels could add around £1,800 to house prices, according to a new survey from Solar Energy UK.
- Sono unveils new solar-powered light electric vehicle for last-mile deliverieson October 6, 2021 at 7:34 pm
Sono unveils latest prototype of a light-electric-vehicle with integrated solar panels. "Our aim is to make every vehicle a solar vehicle," it says.
- Report: Solar panels are serving to warm up property valueson October 6, 2021 at 4:05 pm
Industry calls on finance firms to consider benefits of solar installations, as new report details how solar energy systems increase house values and reduce energy bills ...
- Solar energy creates a positive impact. But how do we use it! (11)on October 5, 2021 at 1:24 am
With a worldwide market share of 95%, crystalline silicon still forms the basis for most (PV) solar panels. But the potential for further improvement and cost reduction is enormous.
- Op-Ed: Plain glass as a solar panel – It’s here, it works, and it’s incredibly usefulon October 1, 2021 at 9:14 am
Glass is ubiquitous in human existence. It uses up a lot of space, and that space has just become a lot more useful. New technology from a company called Ubiquitous Energy in California has developed ...
via Bing News