Korean-Style 'Bakmaktayangjeonji' Achieves World’s Highest Efficiency

Two types of particle size distributions and liquid residues observed in the cross-section of the CZTS light-absorbing layer and solar cell

[Asia Economy Reporter Junho Hwang] Domestic researchers have developed next-generation thin-film solar cell technology that significantly improves efficiency using inexpensive materials. The research team has entered the commercialization phase and is expected to contribute to the advancement of solar technology and the thin-film solar cell industry in the future. On the 15th, Daegu Gyeongbuk Institute of Science and Technology (DGIST) announced that Dr. Jin-kyu Kang's research team at the Thin-Film Solar Cell Research Center discovered for the first time a liquid phase (L-CTSe) that aids the growth of particles necessary for synthesizing the light-absorbing layer during the CZTS thin-film solar cell process.

Unveiling the Secret of the Thin-Film Solar Cell Light-Absorbing Layer

The research team observed the manifestation of a liquid phase in the light-absorbing layer of the CZTS thin-film solar cell and identified for the first time that this liquid phase is related to the formation of the light-absorbing layer. They also found that controlling the liquid phase allows the formation of the light-absorbing layer even at low temperatures.

The CZTS thin-film solar cell forms a thin film by placing related materials?molybdenum, zinc, copper, and tin?on a glass substrate and using a vacuum process. This metal thin film is synthesized through a heat treatment process to become the light-absorbing layer that absorbs sunlight. During this process, a liquid phase containing copper, tin, and selenium appears inside the thin film.

The research team observed particles of various sizes composed of copper, zinc, tin, sulfur, and selenium inside the thin film containing the liquid phase. Small particles easily dissolved in the liquid phase and combined with larger particles, growing even bigger. These grown particles formed the light-absorbing layer composed of copper, zinc, tin, sulfur, and selenium compounds.

World-Class Photoconversion Efficiency

Director Kang Jin-kyu (front right) of the Thin-Film Solar Cell Research Center, Principal Researcher Kim Dae-hwan (front left), and the research team

The CZTS thin-film solar cells developed at the DGIST Thin-Film Solar Cell Research Center use inexpensive and nearly non-toxic copper, tin, and zinc as the main materials. Unlike CIGS thin-film solar cells, which use expensive indium and gallium, or perovskite cells containing toxic heavy metals like lead, CZTS cells are easier to mass-produce. In particular, the CZTS thin-film solar cells developed by the DGIST research team have achieved a world-class photoconversion efficiency of 12.6%, and commercialization research is underway.

Daehwan Kim, principal researcher at the Thin-Film Solar Cell Research Center, said, "We confirmed that residual solid-state materials formed as the liquid phase cooled exist partially at particle boundaries. If these can be removed through further research, device efficiency can be further improved." Center Director Jin-kyu Kang stated, "We aim to continue leading future solar material technology using universal materials and contribute to the development of the thin-film solar cell industry."

Meanwhile, the research results were published in April in the international energy journal Advanced Energy Materials.

This content was produced with the assistance of AI translation services.