Topics that shape the future
- Closer look at research results -

The research topic this time is "Development of an easily recyclable curved, ultra-lightweight crystalline silicon solar cell module."
The general solar cell modules currently used outdoors are mainly made of crystalline silicon, but to make them less likely to break in the harsh outdoor environment, which includes various shocks and temperature changes, they are firmly sealed with a resin called an encapsulant and reinforced glass on the surface. This is why, despite being a delicate electronic device, they can be installed outdoors for over 20 years and still be used even when exposed to the environment.
Currently, the introduction of solar power generation is progressing rapidly around the world, but the lifespan of these solar cell modules is said to be around 20 to 30 years, so it is expected that a large amount of waste will eventually be generated. Recycling technologies to reuse usable materials are being considered and developed, but current solar cell modules are tightly sealed with glass and resin, so they must be crushed to separate the materials, which is very time-consuming and costly.
Therefore, we have been working on the development of an easily recyclable module that does not use resin sealing in collaboration with Professor Keisuke Ohira of the Japan Advanced Institute of Science and Technology since 2021 as part of the NEDO Leading Research Program "Development of a New Concept Crystalline Silicon Solar Cell Module." Since then, with the cooperation of private companies, we have continued the development since 2023 as "Development of an Easily Recyclable Curved and Ultra-Lightweight Crystalline Silicon Solar Cell Module."

Making the structure easy to disassemble will make it easier to recover and reuse the materials used in constructing the modules, and will reduce the discharge of solar cell modules as industrial waste. Solar cell modules in Japan, which have been rapidly introduced since around 2010, will suddenly reach the end of their lifespan after 2030, and according to NEDO's calculations, the amount of waste generated will increase from approximately 3,000 tons in 2020 (0.03% of the final disposal amount of industrial waste in 2015) to approximately 170,000 to 280,000 tons in 2036 (1.7% to 2.7%).

Currently, not all installed solar cell modules will break down at the same time. Due to differences in the performance of the parts used in each module, it is expected that they will gradually reach the end of their lifespan. However, as I mentioned at the beginning, it is thought that many modules will reach their limit after 2030, so we are working with external partners to develop the new modules we are developing in this project, with the expectation that they will be in practical use by that time.

My current research field is photoelectric conversion materials such as solar cells, thermoelectric conversion materials, and their devices and reliability, but I first became interested in solar cells when I was in elementary school. I read an article in a science magazine that said, "One hour of sunlight is enough energy to power the human race on Earth for one year," and even as a child I was so impressed that it inspired me to embark on this path.
After that, by the time I was in high school, I had completely forgotten about that thought, but when I was taking a lecture on semiconductors at university and heard about solar cells, the interest I had as a child was suddenly revived, so I went straight to the library after the lecture and read several related books in one go. I researched solar cells in graduate school, and my career there has continued to the present day.
Semiconductors are used in all kinds of electronic devices, including the smartphones we all carry in our hands, but when they are used in solar cells, they become materials that generate energy rather than consume it. This interest is a major reason why I decided to fully pursue this research field.
My impression of the students at our university, including those in my lab, is that they are very frank and serious, and if they don't understand something, they will come to me and ask me. Our faculty also provides an environment where they can enjoy learning according to their interests. If you lose interest in your research topic, studying becomes less fun, but College of Science and Engineering at Aoyama Gakuin University has a wide variety of research topics, so I think it is an environment that can be recommended to those who want to conduct research activities according to their own interests.

Currently, there are two major barriers to solar power generation. The first is the barrier of photoelectric conversion efficiency. The efficiency of converting light into electrical energy in typical solar cells currently used outdoors is already approaching its theoretical limit. The other problem is that current solar power generation modules require a vast installation area. There are only a limited number of places where equipment can be installed without problems, and in mountainous areas, there are problems such as deforestation. Naturally, guidelines regarding installation have been established, but will they be properly followed? Another major issue is whether or not space can be secured to increase power generation in the future.