江口 大地

Hot electrons in semiconductors have excess energy compared to the band gap, and their utilization holds promise for enhancing the efficiency of photoenergy conversion materials. Copper doping has emerged as a powerful strategy for suppressing hot electron relaxation in colloidal quantum dots (QDs). However, their impact on nanorods (NRs) remains unclear. NRs exhibit a substantial absorption cross-section relative to QDs, rendering them promising materials for enhancing the photoenergy conversion efficiency. In this study, we synthesized Cu-doped CdSe NRs and analyzed their elementary exciton processes using picosecond luminescence and femtosecond transient absorption spectroscopy. Although Cu-ion doping slightly suppressed the relaxation of hot electrons, its efficacy was not comparable to that observed in QDs, even with ∼10% Cu-ion doping. Temperature-dependent experiments revealed that the relaxation of hot electrons in CdSe NRs proceeds mainly by phonon scattering. This research offers a foundational framework for hot electron utilization in NRs, highlighting the pivotal role of phonon manipulation in effectively harnessing their potential.