| 초록 |
Strong van der Waals interaction between large planes of neighboring nanoplatelets (NPLs) induces rapid clustering of NPLs into microstructures. The aggregation typically results in significant drop of photoluminescence (PL) quantum yield (QY) as a result of energy transfer. In this study, we report that assembled Cu-doped CdSe NPLs exhibit increased PL QY (31.1%) in reference to the colloidal solution in hexane (21.0%). The increase presents stark contrast to the case of assembled undoped CdSe NPLs, whose PL QY took a substantial hit from 24.5% to 4.6% upon clustering. Analyses on PL decay dynamics and photobrightening phenomenon reveal that the increase in PL QY of assembled Cu-doped CdSe NPLs results from suppression of electron trapping, since the electrons travelling across neighboring NPLs fill electron trap sites effectively. Unfluctuating conduction band edge energy is responsible for this unique trend because of absence of inhomogeneous broadening of NPL. |
