3月4日、第55回 有機エレクトロニクス研究センター講演会を有機エレクトロニクス研究センター（10号館）4階 会議室にて開催しました。
今回は、フロリダ大学からDr. Franky Soを講師としてお迎えし、「Energetic Disorder and Carrier Transport in Photovoltaic Polymers」という題で講演をして頂きました。
講演会には、50名を超える多くの研究者、学生が参加し、盛況のうちに終了しました。
 当日の会場の様子 |  Dr. Franky So, R.E. Hummel Professor in Electronic Materials and Associate Chair of Research Department of Materials Science and Engineering, University of Florida |
日時 | 3月4日（月） 午前10時30分～午後12時00分 |
会場 | 有機エレクトロニクス研究センター（10号館）4階 会議室 |
講師 | Dr. Franky So, R.E. Hummel Professor in Electronic Materials and Associate Chair of Research Department of Materials Science and Engineering, University of Florida |
演題 | "Energetic Disorder and Carrier Transport in Photovoltaic Polymers" |
Solution processable polymeric solar cells have drawn a lot of attention due to their potential for low cost roll-to-roll manufacturing. Compared with inorganic semiconductors, polymer semiconductors have relatively low carrier mobilities and therefore carrier transport is considered a limiting factor determining the performance of a polymer solar cell. In addition to carrier mobility, carrier lifetime in the polymer:fullerene blends is another important parameter determining the cell efficiency. We have extensively studied the carrier transport and recombination properties of several donor-acceptor conjugated polymers. We found that while low mobilities in polymers lead to charge imbalance, high mobilities do not always lead to high power conversion efficiencies. In this presentation, we will present our device results based on dioctyldithieno silole (DTS) polymers with a wide-absorption band and excellent transport properties. Even though the DTS polymers have a high hole mobility, the power conversion efficiency of the resulting solar cells is limited by the low fill factor. In order to study the loss mechanism of the photo-current, we carried out transient photo-voltage (TPV) measurements to probe the bimolecular recombination of photo-carriers under open circuit condition. Based on our photo-CELIV (carrier extraction by linearly increasing voltage) data, we found that the carrier recombination rate is strongly related to the energetic disorder of the semiconductor polymers. Finally, we will report on our recent progress of high efficiency polymer solar cells based on a low band-gap polymer having an alternating dithienogermole-thienopyrrolodione repeat unit (PDTG-TPD).
