Element doping-induced effects in Zn-doped CdTe quantum-dot system: Insights from an ultrafast dynamics perspective

Element doping can have a profound impact on the photoelectrochemical properties of quantum dots (QDs); nevertheless, the hitherto known information in this regard is mainly from the steady-state characterizations and remains lacking input from the dynamics perspective. Herein, we present a systematic scrutiny of the element doping-induced effects in Zn-doped CdTe QDs. By means of steady-state/time-resolved/temperature-dependent photoluminescence spectroscopy and ultrafast transient absorption spectroscopy, we reveal that the slight Zn-doping in CdTe QDs can greatly affect the involved carrier relaxation dynamics through a density-of-state modification for both near-band-edge and localized surface trap states. Furthermore, such slight doping is found to be quite significant in modulating the photoreduction efficiency (of particular relation to the localized surface trap states) as well as altering the involved relaxation/reaction activation energy and phonon effect in this QDs system. This work enriches our fundamental understanding of the element doping-induced surface/interface effects, from the dynamics perspective in particular, and, hence, offers helpful guidance for QDs-based photoelectrochemical design and optimization.