Quantum-dot coating can turn window into solar panels

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Researchers at the Los Alamos National Laboratory in New Mexico have developed a film of quantum dots that can turn windows into photovoltaic systems.

Quantum dots can be used as semiconductors. According to IEEE Spectrum, they consist of a CdSe inner core, a Cd1−xZnxS outer shell and a silica coating that prevents them from oxidation. The quantum dots are spead into a thin sheet that can be placed onto a glass window pane.

When photons from sunlight hit a quantum dot, it sends the electron in the valence band into the conduction band, leaving a hole behind. When the electron recombines with the hole in the valence band, a new photon with lower energy is generated.

This new photon propagates within the glass via internal reflections. Energy is then generated when the propagating photons reach the window frame, where solar cells are stored.

The coating of quantum dots can be used on any window and to turn it into a sunlight harvesters at costs lower than are currently available.

The study was published in Nature Energy on Oct 10.


RUNDOWN SHOWS:
1. Depiction of a conventional silicon solar panel
2. Layers of a quantum dot
3. Depiction of quantum dots made into a thin film and placed on a glass
4. Depiction of exciton energy in a quantum dot
5. Photons propagate in the glass
6. Photons reaching the solar cells in the window frame
7. Depiction of quantum-dot coating applied on windows in a building; depiction of energy is generated

VOICEOVER (in English):

“When sunlight hits conventional silicon solar panels, electrons break free of the top layer of semiconducting material. The electrons then follow conductors between the positive and negative sides of the panel to generate an electrical current.”

“Quantum dots, which have an inner core, an outer shell and a silica coat can be used as semiconductors.”

“Quantum dots can be spread into a thin sheets that are placed onto glass window panes.”

“When photons from sunlight hit a quantum dot, it excites the electron in the valence band and sends it into the conduction band, leaving a hole behind. When the electron recombines with the hole in the valence band, a new photon with lower energy is generated.”

“This new photon then propagates within the glass via internal reflections.”

“Energy is generated when the propagating photons reach the window’s frame, where solar cells are stored.”

“Coatings of quantum dots can be used on any window to turn them into harvesters of sunlight at lower costs than is currently available.”


SOURCES:
http://spectrum.ieee.org/energywise/energy/renewables/quantum-dot-coating-could-pull-solar-energy-from-your-windows
http://www.lanl.gov/discover/news-release-archive/2015/August/08.24-capture-sunlight-with-window.php
http://www.nature.com/articles/nenergy2016157
http://www.govtech.com/fs/infrastructure/Tech-Startup-Gets-Funding-to-Harness-Energy-from-Solar-Rays-Beaming-Through-Windows.html
http://www.energy.gov/articles/turning-windows-solar-panels
http://science.howstuffworks.com/environmental/energy/solar-cell2.htm