These Quantum Dot Solar Cells Have No Toxic Elements

The conversion efficiency of quantum dots is fast approaching the efficiency of conventional solar cells


Researchers at the Los Alamos National Laboratory (LANL) have come up with new quantum dot solar cells that can match the efficiency of the existing quantum dot-based devices.

The best part of this development is that these quantum dot solar cells don’t use lead or any other toxic elements that most solar cells rely on. The news was made public by the laboratory in a report featured in the science journal, Nature Energy.

Speaking on this latest development and the future of quantum dot cells, Viktor Klimov, lead author of the report, said, “This quantum-dot approach shows great promise for a new type of toxic-element-free, inexpensive solar cells that exhibit remarkable defect tolerance.”

The researchers at the laboratory demonstrated the process underlying the defect tolerance of these devices. Instead of impeding the photovoltaic functions, the defect states in copper indium selenide quantum dots helped in increasing the photoconversion process of these devices.

As per the study, quantum dots are great light emitters and are now being used in several devices like color displays, televisions, and very soon, they will be used in the making of color adjustable light bulbs.

The unique nature of nanosized quantum dots has fascinated researchers for long, and the best part of these nanocrystals is that they can be manipulated at the fundamental level. Because of this nature, they are called “quantum dots.”

According to the study, one among the many properties of quantum dots is that they can capture sunlight, which is of great use in the solar-energy conversion. The conversion efficiency of quantum dots is fast approaching the efficiency of conventional solar cells, and these dots don’t contain any heavy toxic elements like lead or cadmium, which are present in traditional thin-film solar cells.

The researchers added that high-quality quantum dots were free from any toxic elements. The team at the laboratory used a reaction of copper, indium, and selenium, with the addition of zinc to developing zinc-doped quantum dots. These zinc dots were then added into the voids of titania film, and the film was then exposed to the sunlight, which led to the release of the tightly bound electrons producing a photocurrent.

“Due to their very complex composition, these dots are prone to defects. Despite these imperfections, they showed nearly perfect performance in our solar cells—per each 100 absorbed photons, we detected 85 photogenerated electrons, implying that the photon-to-electron conversion efficiency was 85 percent,” added Klimov.

The high conversion efficiency of quantum dots along with high defect tolerance and the absence of any toxic material make these quantum dots a promising proposition for the development of highly efficient solar cells in the near future, which are inexpensive and readily scalable.

In February this year, researchers at the University of Queensland came up with a flexible skin that can be put over hard surfaces to convert solar energy to electricity. The team of researchers at the University achieved 16.6% efficiency for quantum dots surpassing the previous world record of 13.4%.

Earlier, Mercom had reported that combining thin-film solar modules based on perovskite semiconductors with semiconductors made of copper, indium, gallium, and selenium, solar module technology could cross the 30% efficiency mark, according to a study conducted by the Karls-ruhe Institute of Technology, Nice Solar Energy, and the Centre for Solar Energy and Hydrogen Research Baden-Württemberg.

Image credit: LANL