CdSe(Te)/CdS/CdSe Rods Versus CdTe/CdS/CdSe Spheres: Morphology-Dependent Carrier Dynamics for Photon Upconversion

Colloidal quantum dot (QD) hybrid nanostructures have been shown to upconvert two low-energy photons into one high-energy photon and have wide ranging applications, including in photovoltaics, where additional current in the solar cell can be generated from the absorption of upconverted light emitted from the nanostructures. Both double QDs (via nanorod formation) and quantum dot-quantum well structures have been studied previously, but there has been no systematic study of the dependence of carrier dynamics on nanostructure morphology. Here, we synthesize both core/multishell colloidal QD and core/rod complexes and use steady-state and time-resolved photoluminescence to elucidate carrier separation and transfer dynamics. Understanding these dynamics provides important information for optimizing the nanostructure morphology to create more efficient photon upconversion and, thus, enhance net solar conversion efficiencies.