Development of organic inorganic perovskite high performance solar cells

The global solar industry is growing year on year on the back of silicon solar cells, which are currently the only efficient and affordable technology for large-scale use. Although silicon has many advantages, silicon cells dramatically reduce their output voltage in weak light conditions and because of opaque body they cannot be applied to window, which comprises much of the cladding on today's skyscrapers. Miyasaka has been working for perovskite-based solar cells since his first discovery in 2009. When applied to sunlight absorber, the perovskite, an organic inorganic hybrid semiconductor, was found to be capable of high power conversion efficiency beyond 23%, which approaches the top efficiency of silicon solar cell. Miyasaka says: 'Preparation of high purity metallic silicon ingot requires a melting temperature of 1400oC and the manufacturing process requires a large up-front investment in high temperature and vacuum equipment'. This process cost constrains supply and puts a bottom limit on prices. Competitive materials under development and currently entering the market are either based on rare or toxic materials, or are not yet performing in line with silicon. He says: 'Perovskite solar cells (PSCs) can be made quite cheaply and have superior performance under weak light, gifted by its high-voltage-output performance which is enabled by defect-tolerance nature of the hybrid perovskite material.' He adds: 'PSCs can also be made into mechanically flexible and lightweight thin-films for attachment to clothes and windows, for powering the Internet of Things (IoT) and whole buildings.' His devices are also being tested for use in space and are showing good resistance to bombardment by radiation. He expects his research to yield commercially viable perovskite-based solar cells within the next five years.

Miyasaka has a broad range of collaborators and believes his ability to build networks and be open-minded to other research fields enabled him to discover the solar-absorbing properties of wide-spectrum lead halide perovskites. He says: 'Collaboration with people working in different areas is necessary to achieve innovative work,' adding: 'my present collaborators are 50 per cent physicists because perovskite research requires an interdisciplinary approach'. He has Japanese collaborators who are experts in the electron structures of semiconductor materials and is also working with JAXA. In Europe, he collaborates with crystallographers, theoretical chemists and other researchers examining the optical properties of perovskites. Miyasaka says: 'China is likely to be commercialising perovskite-based solar cells within the next two years'. Miyasaka also talks regularly with research groups around the world working on what could be considered competitive materials.