From the Department of Energy and Electronic Materials, Korea Institute of Materials Science, Dr. A research team led by Jung Dae-Kwon has succeeded in creating the world’s first transparent thin-film solar cell on a flexible substrate that exhibits different reflective colors. does not significantly reduce the efficiency of the solar cell. The results of the research were published at: Journal of Chemical Engineering.

It is a technology that provides a reflective color in a single material by periodically adding hydrogen to aluminum-doped zinc oxide, which is a transparent electrode, creating a difference in the refractive index.

By developing a multilayer thin film with a refractive index difference of less than 5%, the reflection loss in the visible light region absorbed by the solar cell device is minimized. It can be applied to a variety of absorbers for thin-film solar cells because it hardly reduces the efficiency of solar cells due to color rendering. Additionally, it is expected to serve as a reference point to improve the aesthetics of transparent thin-film solar cells with flexible substrates for BIPV (Building Integrated Photovoltaic) and VIPV (Vehicle Integrated Photovoltaic).

To date, multilayer thinning technology for materials with large refractive index differences, color-controlled thin-film coating technology to improve optical properties, and structural color technology to imitate natural structure have been used as color application methods to improve the aesthetics of transparent thin materials. film solar panels. Cells However, these technologies are not suitable for solar cells that absorb visible light due to the wide reflectance band and high reflectivity, or require complex technologies that are difficult to implement industrially in terms of two or more materials and processes.

The research team created multilayer thin films with different refractive indices using periodic hydrogen reactions during the deposition of zinc oxide thin films using a vacuum sputtering method used in common semiconductor and solar cell manufacturing processes. They then adjusted the thickness of the multilayer thin film to achieve the three primary colors of light. At that time, the color of the electrode was well noticeable even when applied to a solar cell that absorbs light in the visible light range.

Multilayer transparent thin film electrode based on a single material does not require additional processing. Color diversity and high efficiency of thin-film solar cells are expected to be realized at low cost. Also, since the reflective color is applied as an optical filter, it can be applied to various fields such as image sensors, photolithography masks and infrared shielding.

Principal investigator Dr. Jeong Dae-Kwon said: “When this technology is commercialized, it will assist in the development of simple and process-free light filter technology and high-efficiency thin-film solar cells with transparent colored flexible substrate, as well as the realization of modern BIPV systems. Buildings and VIPV systems for vehicles with aesthetic properties. “.

This research was carried out as part of the Korea Institute of Materials Science Basic Research Project and the Korea Energy Technology Evaluation and Planning Institute Energy Technology Development Project. Based on this work, the research group is actively conducting further research in the field of color-expressing solar modules, considering both the aesthetic and practical aspects of BIPV. Source