Femtosecond Spectroscopy of Carrier Relaxation Dynamics in Type II CdSe/CdTe Tetrapod Heteronanostructures

Abstract

Branched nanocrystal heterostructures synthesized from CdSe and CdTe exhibit a type II band structure alignment that induces separation of charge upon photoexcitation and localizes carriers to different regions of the tetrahedral geometry. The dynamics of carrier relaxation examined with femtosecond pump-probe spectroscopy showed heterostructures having rise times and biexponential decays longer than those of nanorods with similar dimensions. This is attributed to weaker interactions with surface states and nonradiative relaxation channels afforded by the type II alignment.

Theory of coherent phonons in carbon nanotubes and graphene nanoribbons

“…The development of ultrafast, femtosecond laser sources has enabled researchers to study dynamical properties of molecular systems, semiconductor nanostructures, and carbon nanotubes [20,[60][61][62][63][64][65][66]. Ultrafast femtosecond lasers are ideal for studying electron and hole dynamics since scattering rates typically range from 10 to 100s of femtoseconds in most semiconductors [67,68].…”

Atomistic Simulations of Functional Au144(SR)60 Gold Nanoparticles in Aqueous Environment

“…7 Other size-dependent properties include surface plasmon resonance in metal NPs,8 quantum confinement effects in semiconductor NPs (quantum dots), 9 and superparamagnetism in magnetic materials. 10 The changes in physical properties are not always desirable, and,…”

“…6 For phase-change materials used in optical data storage and nonvolatile computer memory, chalcogenide (e.g., GeTe) NPs offer an intriguing route of manufacturing composite materials with tuned (size-dependent) melting point and recrystallization temperature. 7 Other size-dependent properties include surface plasmon resonance in metal NPs, 8 quantum confinement effects in semiconductor NPs (quantum dots), 9 and superparamagnetism in magnetic materials. 10 The changes in physical properties are not always desirable, and, e.g., the magnetization direction of small ferromagnetic NPs can switch at low temperature, making them unsuitable for applications.…”

“…3,4 Nanoparticles often display fascinating optical properties because of quantum effects, and, e.g., gold nanoparticles (AuNPs) appear from yellow to deep red and black in solution depending on their size. 5 In photovoltaic cells, absorption of solar radiation is much higher for semiconductor materials comprised of NPs than for continuous sheets of thin films (e.g., CdTe, ZnO).6 For phase-change materials used in optical data storage and nonvolatile computer memory, chalcogenide (e.g., GeTe) NPs offer an intriguing route of manufacturing composite materials with tuned (size-dependent) melting point and recrystallization temperature.7 Other size-dependent properties include surface plasmon resonance in metal NPs,8 quantum confinement effects in semiconductor NPs (quantum dots), 9 and superparamagnetism in magnetic materials. 10 The changes in physical properties are not always desirable, and,…”

Supported plasma-made 1D heterostructures: perspectives and applications

“…Numerous examples are available in the most recent literature where different supported 1D nanostructures are prepared by using wet chemical and electrochemical routes [13], vapour phase condensation methods (e.g. vapour-liquid-solid, VLS methods) [14], solution-phase methods [15], template directed synthesis [16] or other evaporation based approaches [17,18], etc. An important advantage of the 1D over the 2D nanostructures and thin films is the facile fabrication of 1D defect-free heterostructures, and the tailored synthesis of multicomponent materials and heterojunctions with controlled 1D morphology (e.g., core@shell nanofibres, metal decorated CNTs and oxide nanowires, nanobrushes, segmented, cross junctions or branched 1D nanostructures) [10,[19][20][21].…”