[11p-M103-1~10] 13.6 ナノ構造・量子現象・ナノ量子デバイス

▲ [11p-M103-1] Multiple exciton generation rate in CsPbI₃ quantum dots

〇Dolf Timmerman¹、Eichi Matsubara²、Leyre Gomez³、Masaaki Ahida¹、Tom Gregorkiewicz^3,1、Yasufumi Fujiwara¹ (1.Osaka Univ.、2.Osaka Dental Univ.、3.Univ. of Amsterdam)

キーワード：Multiple exciton generation, Perovskite, Quantum dot

The multiple exciton generation (MEG) process has been extensively investigated in a wide variety of quantum dots. After absorption of high energy photons, hot excitons are formed, which will subsequently cool down to the band edge. The splitting of a hot exciton into two, or more, lower energy excitons, is also possible. In general, the carrier generation yield is determined by the competition of exciton cooling processes and the MEG rate. Although the determination of cooling rates is well-established, a direct observation of the MEG rate has so far been lacking, resulting from the short timescales and fast competing cooling processes. Here, we present a study on the ultrafast carrier dynamics of CsPbI₃ quantum dots and determine both the exciton energy cooling and MEG rates. We find an exciton energy cooling time of 1 eV/ps and MEG rate of 2.5 s^-1, respectively. For the first time the MEG process is also observed directly, as a delayed carrier buildup following an excitation pulse.