Effect of Cu-ion\nDoping on Hot Electron Relaxation\nin CdSe Nanorods

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