Principal Investigator Kazumi Wada
Solar energy is clean, and an infinite power source as far as lifetime of the human beings on the earth is concerned. Another feature of solarcells "distributed power sources" will be even more important in terms of home-land security. Kazumi Wada's current activity is focused on Si solarcell with an enhanced efficiency beyond the current record (24.5%). To breakthrough the low efficiency the low absorption coefficient of Si has to be engineered especially near bandgap region because it is too weak due to the indirect bandgap characteristics. His approach is to implement photonic nano-structures with solution chemistry and to realize the superprism effect to enhance bandedge light absorption (Super Solarcells). He is also working to generate electricity from heat so far wasted, based on monolithically integrated Ge thermo-photovoltaic cells on Si.