Vol.5 No.4 2013
Research paper : Development of switchable mirror glass (K. Yoshimura et al.)−269−Synthesiology - English edition Vol.5 No.4 (2013) the conventional electrochromic material that uses tungsten oxide thin film as the switchable layer, the switchable mirror using the magnesium alloy thin film had not been realized. Initially, the device was fabricated by layering the switchable, electrolyte, and counter electrode layers according to the structure of conventional all-solid-state switchable electrochromic element, but the device did not work. As a result of reviewing why it did not function, we thought that the layers should be reversed for the switchable mirror. We created a device with the reverse structure, and were able to develop a device with a good switching function. This reversed multi-layer thin film structure is our original idea.4 Organization of the issues for achieving practical use of the switchable mirror glassQuestion (Kazuo Igarashi, Institute of National Colleges of Technology, Japan)As the three issues in achieving the practical use of the switchable mirror glass, you mention the improvement of optical property, the improvement of durability, and the development of an electrochromic method. While the former two are essential issues that must be cleared, the third does not seem to be a requirement since it depends on the use. What are your thoughts on this?Answer (Kazuki Yoshimura)Since the usage of a gaschromic method is very limited, switching by an electrochromic method is important in achieving practical use. In 2002, we had no idea whether switching could be done by an electrochromic method for the magnesium alloy thin film, and it was an important point in the practical use research of the switchable mirror.5 Positioning of the upsizing technology in achieving practical use of the switchable mirror glassQuestion (Kazuo Igarashi)In upsizing from the laboratory level to actual use level, it can be expected that new issues will arise such as optical property or durability. Therefore, I think upsizing was a major issue in practical use, but it is not mentioned in this paper. How should I consider the positioning of upsizing in the practical use strategy?Answer (Kazuki Tajima)Upsizing can be done relatively easily for the gaschromic method, while it is a problem for the electrochromic method. I added some description on this point.6 Durability of the switchable mirrorQuestion (Norimitsu Murayama)You mention that the durability for repeated switching in achieving practical use of the switchable mirror is currently about 1,500 times. What is the prospect of extending the durability to about 10,000 times?Answer (Yasusei Yamada)For durability, there was a major progress recently, and we are finding out that we may be able to develop a switchable mirror material with hardly any deterioration. By developing this technology, we have the prospect of creating a material with durability of about 10,000 times within this fiscal year.7 Efforts for achieving practical use of the switchable mirror glassQuestion (Norimitsu Murayama)You quantitatively demonstrated the energy-saving effect of the switchable mirror glass at the Environment Friendly Experiment Building. As a result, how did the way the industry look at switchable mirror glass change? Also, do you have any plans such as setting up some corporate consortium as the scenario for achieving practical use of the switchable mirror glass?Answer (Kazuki Yoshimura)For the switchable mirror, the people of the glass manufacturers have been paying attention to it since 2003 as a new switchable material. However, due to the historical progress as described in this paper, they decided to sit and wait to see whether this material could actually be put to use. In such a situation, fabricating the switchable mirror windowpane that can be actually installed in a building and demonstrating the large cooling load reduction effect compared to other energy-saving glass materials were regarded with great enthusiasm. The glass manufacturers are specifically considering joint research.To take the switchable mirror glass to the stage of an actual product that can be used as the windowpane for buildings, the developments of parts other than the switchable mirror thin film, such as the switching system that can be used in actual windowpanes and its power supply system are necessary. Currently, the research is being continued, and the prospect for practical use is good if these issues are solved. At that point, we plan to make powerful appeals to the glass manufacturers and accelerate the practical use research by perhaps forming a consortium.