BEIJING, March 29 (Xinhua) -- Scientists in the Netherlands and the United Kingdom have used a nano-textured structure to make thin-film silicon photovoltaic cells opaque and thus enhance their efficiency in absorbing sunlight. The experimental results show that the thin-film cells designed with the new method can absorb 65 percent of sunlight, which is the highest light absorption rate ever exhibited by a thin silicon film and is close to the theoretical absorption limit of about 70 percent, promising flexible, lightweight and efficient silicon photovoltaic cells. The research was published in the journal American Chemical Society - Photonics.

Silicon solar cells, with their high efficiency and raw material of silicon, which is abundant in the earth, are considered highly efficient photovoltaic technologies. However, they require the use of thick, hard, heavy wafers, so their use is limited. Using thin films reduces silicon use by 99% and makes the cells lighter and more robust, easily integrated into urban buildings and even small everyday devices. However, thin silicon films can only absorb 25% of the sun's rays. With this in mind, researchers at the National Institute for Atomic Molecular Research (AMOLF) in the Netherlands, the University of Surrey in the UK and Imperial College have improved it.

The researchers explain that the nanostructures they designed using the new method have a super-uniform distribution pattern on the surface that confines direct sunlight to an angular range, thereby trapping more light within the silicon film. The more light that is trapped, the greater the chance that it will be absorbed. Studies have shown that ultra-uniformly distributed patterns can better confine the angle of incidence of sunlight, allowing more sunlight to be absorbed.

In addition, there are two key challenges to capturing sunlight into thin silicon: sunlight contains multiple colors, and silicon films are limited in size, and silicon absorbs each color of light differently. The study found that thick silicon solar cells with a pyramid-shaped surface coating and patterns similar in size to the wavelength of light could solve this problem.

We estimate that 1-micron-thick carbon-silicon cells can achieve photovoltaic conversion efficiencies of more than 20 percent, a major breakthrough for flexible, lightweight carbon-silicon photovoltaic cells," said Esther Alakan Lado of AMOLF, who led the latest study. The study also found that high-efficiency thin silicon cells could be made from low-quality silicon, which would reduce the energy requirements for purifying raw silicon and shorten energy recovery times."

The researchers noted that although such high-efficiency thin-film cells are still some distance away from applications, ultra-uniform patterned thin-film photovoltaic cells are highly promising.

Translated with www.DeepL.com/Translator (free version)