Lee Tae-woo, Professor of Materials Engineering at Seoul National University, Research Team World's First Development of Perovskite Light-Emitting Materials Announcement on Nature Nanotechnology Attention is focused on 'Post OLED' display materials. Clears and cheaper, applied to extended reality

 

SN Display attended CES in Las Vegas earlier this month and introduced a prototype of a display using 75-inch perovskite light-emitting materials. The left is a perovskite display, and the right is a normal display. [Picture = Professor Lee Taewoo's research team]

Perovskite light-emitting materials are in the spotlight as next-generation display materials that will replace organic light-emitting diodes (OLEDs) due to their high luminous efficiency and color purity. A domestic research team has succeeded in developing perovskite light-emitting materials that show the best luminous efficiency in the world. By breaking the previous record set by the research team once again, the lifespan of the material has also improved by about 3,108 times compared to the previous one. It is expected that it will be a fundamental technology for Korea to maintain its position as a strong player in the global display industry.

The Ministry of Science and ICT announced on the 16th that a research team led by Lee Tae-woo, a professor of material engineering at Seoul National University, has successfully developed perovskite light-emitting materials with high efficiency and long life in the international academic journal Nature Nanotechnology.

Perovskite is a crystal structure that has a chemical formula in the form of "ABX3," such as "calcium titanate (CaTiO3)", and refers to a metal oxide with a special structure that shows not only the properties of nonconductors, semiconductors, and conductors but also superconductivity. It is also attracting attention as a next-generation solar cell material that will replace silicon solar cells because it produces electrons and holes that transmit electricity when receiving sunlight.

Recently, it has been evaluated as having high potential as a display material. The perovskite light-emitting material for display is made of a crystal structure composed of organic molecules, inorganic elements, metals, and halogen elements. Compared to quantum dots and oil-emitting materials of QLED, which are currently used as display materials, color purity is higher and color adjustment is easy, but production cost is low. It is used in augmented and virtual reality (AR and VR) devices that require high performance and is expected to lead the next-generation display industry.

But there is still a mountain to overcome. Perovskite light-emitting materials have lower luminous efficiency than commercially available organic light-emitting materials. Currently, the efficiency has reached 28.9%. Kim Sung-jin, a Ph.D. student who participated in the study as the first author, said, "The luminous efficiency of organic light-emitting materials is about 37 to 38%, so similar efficiency levels must be achieved for perovskite light-emitting materials to be commercialized."

SN Display set up a booth at CES held in Las Vegas earlier this month. Professor Lee Tae-woo of Seoul National University is posing with a display prototype using 75-inch perovskite light-emitting materials. [Picture = Professor Lee Taewoo's research team]

The research team achieved high efficiency by introducing a "Tandem" structure. The tandem structure is a structure in which two or more single structural materials are stacked, and simultaneously induces light emission in multiple light emitting layers. Accordingly, the luminous efficiency of the material may be greatly improved.

The research team merged perovskite light-emitting materials and organic light-emitting materials. It developed a perovskite light-emitting material in the form of a 'hybrid'. "It is the world's first hybrid perovskite light-emitting material," the research team said. "The luminous efficiency of this material is 37% very high," and "It is the maximum luminous efficiency that can be implemented in theory."

Professor Lee Tae-woo's team is considered the best group of experts in the field of perovskite light-emitting materials. In 2022, it also announced in the international academic journal Nature that it has developed a technology that dramatically improves the luminous efficiency and brightness of perovskite light-emitting materials. The research team was evaluated as proving the possibility that the perovskite light-emitting material at the time could go beyond the laboratory level and lead to commercialization.

The research team said, "This study differs from past studies in that it greatly improved the lifespan of perovskites." In fact, the newly developed perovskite has a lifespan of 5,596 hours. This is an improvement of about 3108 times compared to the previous 1.8 hours.

The research team also founded a company called "SN Display" in 2020, which focuses on perovskite light-emitting materials. SN Display attended CES in Las Vegas earlier this month and introduced a prototype of a display using 75-inch perovskite light-emitting materials. SN Display plans to continuously supplement its technology to spur the creation and preoccupation of related markets.

The remaining technical challenge is to develop blue and red perovskite light-emitting materials. The development in this study is a green light-emitting material. The research team said, "It is more technically difficult to make blue and red light-emitting materials," adding, "Improving the stability of light emission remains a task." After solving these challenges, it is expected that commercial products will be released within the next five years.

Professor Lee said, "This study presented guidelines for constructing materials to satisfy both efficiency and high color purity by stacking different light-emitting materials," adding, "Commercialization of perovskite light-emitting materials will be possible faster than expected."

■ Terminology Description ▶ Perovskite: a mineral with an unusual regular three-dimensional structure in which two cations and one anion are combined. It is attracting attention as a next-generation solar cell material to replace silicon solar cells because it creates electrons and holes that transmit electricity when exposed to sunlight, while drawing attention as a material to replace organic light emitting diodes (OLEDs), which are currently widely used as display materials.

 

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