Quantum innovation advances low-cost alternative solar technology

A team of researchers from the University of Toronto's Faculty of Applied Science and Engineering have used quantum mechanics to modify the active layer within a device known as an inverted perovskite solar cell, a technology that could one day result in mass-market solar cells.

Most commercial solar cells are made from high-purity Silicon, which takes a lot of energy to produce. Alternative solar technologies that could be manufactured and installed with less energy and cost are being explored by researchers.

One of the alternatives being studied is known as perovskite. The power of the materials comes from their unique crystal structure, which allows them to absorb light in a very thin layer and convert it into electricity efficiently.

Perovskite crystals are made from liquid ink and coated onto surfaces using technology that is already well-established in industry such as roll-to-roll printing.

Because of this, perovskite solar cells have the potential to be mass produced at much lower energy costs than Silicon. The challenge is that perovskite solar cells are not stable. We wanted to close that gap in this study.

The co-lead authors are using a strategy based on inverted solar cell structure.

In most prototype perovskite solar cells, electrons exit through a negative electrode at the bottom layer of the cell, with holes at the top.

Past research has shown that alternate manufacturing techniques can improve the stability of the perovskite layer by Reversing this arrangement. The change has a cost in terms of performance.

It is difficult to get good contact between the top and bottom layers. holes can go through this passivation layer in the traditional orientation. electrons are blocked by this layer, so when you invert the cell it becomes a big problem.

The physical principle that states the behavior of materials at very small length scales is different from what is observed at larger ones was taken advantage of by the team.

In our prototype solar cells, the perovskites are confined to an extremely thin layer, only one to three crystals in height. We have the ability to control what wavelength of light the perovskites absorb, or how electrons move within the layer.

The team used a chemical technique to create a two-dimensional surface on their solar cell. The need for the organic layer was eliminated because of this.

The team increased the thickness of the layer from one crystal to three. The prediction was made in the lab that the change would change the energy landscape enough to allow electrons to escape into an external circuit.

After 1,000 hours of operation at room temperature, the power conversion efficiency of the team's cells was at 23.9%. After more than 500 hours of use, the performance only decreased by eight percent when subjected to an industry-standard accelerated aging process.

Future work will focus on increasing the stability of the cells. The current cells are only five square millimeters in size, so the team would like to build cells with a larger surface area.

The current results bode well for the future of alternative solar technology.

In our paper, we compare our prototypes to both traditional and inverted perovskite solar cells that have been recently published in the scientific literature.

The combination of high stability and high efficiency we achieved really stood out. We should keep in mind that Silicon has been worked on for 70 years, while the technology for perovskite is only a couple of decades old. There are still improvements to be made.

More information: Hao Chen et al, Quantum-size-tuned heterostructures enable efficient and stable inverted perovskite solar cells, Nature Photonics (2022). DOI: 10.1038/s41566-022-00985-1 Journal information: Nature Photonics Citation: Quantum innovation advances low-cost alternative solar technology (2022, April 8) retrieved 8 April 2022 from https://phys.org/news/2022-04-quantum-advances-low-cost-alternative-solar.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.