Scientists invented colloidal quantum dots double-layer solar cells

The research team led by Ted Sargent, professor of electrical and computer engineering at the University of Toronto, Canada, has for the first time developed a colloidal quantum dots (CQD) double-layer solar cell that can significantly increase conversion efficiency. Colloidal quantum dots are semiconductor particles that can absorb visible light and absorb invisible light. The theoretical conversion efficiency can reach 42%. The research results were published in the latest edition of Nature Materials magazine.

Scientific research proves that quantum dots are a very promising method that can be sprayed onto various surfaces including plastics, effectively reducing solar cell production costs.

One of the biggest challenges in this area is how to achieve the best combination of convenience and performance. The ideal design is to connect the quantum dots closely. Because of the larger spatial distance of the quantum dots, the photoelectric conversion efficiency is lower.

So far, all quantum dots are blocked in organic molecules. In order to solve the long-range movement of electrons, scientists used inorganic ligands and atoms smaller than nanometers to combine quantum dots. The close-packed arrangement and removal of the negative charge trap ensures that the electrons can move quickly and smoothly in the solar cell, providing conversion efficiency.

In this double-layer solar cell developed by the researchers, one layer of quantum dots is modulated to capture visible light while the other layer is capable of capturing infrared light. In addition, they also introduced a transition layer consisting of four different film-like metal oxides. This method can reduce the interlayer resistance. They choose transparent oxides for this layer so that light can pass through them to the underlying battery.

At present, the conversion efficiency of this double-layer solar cell is 4.2%. The team’s goal is to increase conversion efficiency to 10% over the next five years.

This double-layer battery has the maximum current and the highest conversion efficiency of colloidal quantum dot solar cells. The experimental results have been recognized by Newport, which is certified by the National Renewable Energy Laboratory.

John Asbury, a professor of chemistry at Pennsylvania State University, points out that the team at the University of Toronto has increased the theoretical efficiency from 30% to more than 40% because of the ability to fabricate multilayer quantum dot solar cells.

Sargent said: "The world and the market need innovation to break the existing performance and cost balance. Through the contract with the University of Toronto and the King Abdullah University of Technology, we can turn existing research into real innovation and achieve business. Application." (Translation: Owen)