Novel quantum dot solar cells developed at Los Alamos National Laboratory (U.S.) match the efficiency of existing quantum-dot based devices, but without lead or other toxic elements that most solar cells of this type rely on.
Researchers developed solar panels capable to adapt to different lighting conditions. They can also harness more bands of light than traditional solar panels, ensuring a better performance.
The development is based on a system that synthetizes magnetically charged quantum dots. They capture kinetic energy from the electrons created by ultraviolet light before being wasted as heat.
“This discovery can potentially enable novel, highly-efficient solar cells, light detectors, photocathodes and light-driven chemical reactions,” said Victor Klimov, lead researcher on the Laboratory’s quantum dot project.
Novel #quantum dot solar cells developed at Los Alamos National Laboratory match the efficiency of existing quantum-dot based devices, but without lead or other toxic elements that most solar cells of this type rely on. https://t.co/HQr1Jsde4R
— Los Alamos Lab (@LosAlamosNatLab) May 22, 2020
Free from toxic elements
The highly efficient novel quantum solar cells are free from any toxic elements. The team used a reaction of copper, indium, and selenium, with the addition of zinc to make zinc-doped quantum dots. The dots were incorporated into voids of a highly porous titania film which served as a charge collecting electrode.
The unique physics of the semiconductor crystals of nanometric size prepared by colloidal synthesis has fascinated scientists for decades.
Due to their extremely small sizes – just a few nanometers of diameter – the properties of the nanocrystals can be manipulated at the most fundamental quantum-mechanic level. Hence, their name “quantum dots.”
Cover story: Klimov and team at @LosAlamosNatLab show that, in quantum-dot-sensitized solar cells, charge-trapping defects assist photoconversion and increase efficiency by supporting charge transfer to the electrodes. https://t.co/4cp3Tba98B pic.twitter.com/YMv1reOFnJ
— Nature Energy (@NatureEnergyJnl) May 22, 2020
Not only did the researchers demonstrate highly efficient devices, they also revealed the mechanism underlying their remarkable defect tolerance. Instead of impeding photovoltaic performance, the defect states in copper indium selenide quantum dots actually assist the photoconversion process.
Quantum dots have already found many uses, and more are coming. In particular, they are very efficient light emitters. They are distinct from other types of light-emitting materials, as their color is not fixed and can be easily tuned by adjusting the quantum dot size. This property has been utilized in displays and televisions, and soon will help make more efficient, color-adjustable light bulbs.
They have a high photoconversion efficiency combined with a remarkable defect tolerance and the free composition of toxic elements. These characteristics make these quantum dots very promising for implementing cheap solar cells that are easily scalable and potentially disposable.
The conclusions were published in scientific magazine Nature.
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