Will Flexible Solar Cells Give Japan a Leading Edge in Renewable Energy?

The past 15 years have seen significant advancements in the research and development of perovskite solar cells (PSCs). Developed by a Japanese researcher, PSCs are lightweight and film-like. These solar cells, which use a mineral called "perovskite," offer several advantages over traditional silicon-based cells.

For one, PSCs are flexible and can be installed in various settings. Also, their production process emits less carbon, making them more eco-friendly. For Japan, they add an element of economic security as the raw materials lead and iodine can be sourced domestically. 

A Seminal Paper

Specially Appointed Professor Tsutomu Miyasaka is a leading figure in PSC research. Following his tenure at Fujifilm Corporation, Miyasaka joined Toin University of Yokohama. In 2009, his laboratory published a paper that laid the foundation for PSC research. Since then, the conversion efficiency of these solar cells has massively improved to 26%, comparable to silicon-based solar cells.

Solar cells were first developed in the United States in the 1950s using silicon-based technology. Even today, over 90% of the market is dominated by silicon-based products, most of which are manufactured in China. 

In the early 2000s, amidst rising interest in renewable energy, Japanese pioneers like Sharp Corporation, Kyocera Corporation, and Sanyo Electric spearheaded the solar cell industry. However, as mass production and aggressive price competition intensified, Chinese companies quickly took over. China's solar cell industry is supported by national policy, and the silicon used in these solar cells is also primarily sourced from China.

A Turning Point

The development of perovskite solar cells requires both physical and chemical advancements. In 2012, a graduate student from the University of Oxford, who studied under Miyasaka, announced a conversion efficiency exceeding 10%. This milestone accelerated global research and development efforts. Ironically, one of Miyasaka's Chinese students returned to China to start a perovskite solar cell business, becoming a competitor in the field.

The practical application of perovskite solar cells faces several hurdles, primarily concerning durability and cost. PSCs have yet to reach the 20-year lifespan of silicon-based solar cells.

The installation of silicon-based solar panels in Japan faces constraints due to its small land area. However, the thin and lightweight design of PSCs offers greater versatility. They can be installed on various surfaces, such as poles and walls. Additionally, silicon-based panels are challenging to maintain once installed.

Latest Developments

The Tokyo Metropolitan Government has installed PSCs manufactured by Sekisui Chemical at the Tokyo International Cruise Terminal, one of Japan's largest port facilities. Sekisui Chemical aims to commercialize film-type perovskite by 2025. 

Furthermore, Panasonic Holdings is researching and developing glass-integrated perovskite solar cells for commercialization by 2028.

Meanwhile, railway companies, real estate firms, and local governments are collaborating to test the durability and efficiency of PSCs. University startups are also participating in PSC research. To promote widespread adoption, Japan's industry ministry plans to launch a public-private consortium comprising around 150 organizations, including central government agencies, private companies, and local governments.

Since Miyasaka's seminal paper in 2009, global research and development in PSCs has surged, but Japan lags behind. Whether perovskite solar cells can pave the way for Japan's economy remains to be seen. To avoid repeating the issues encountered with silicon-based solar cells, Japan needs to prioritize research, development, and widespread adoption initiatives for PSCs.

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(Read the article in Japanese.)

Author: Hidemitsu Kaito