Photophysical Properties of CdSe/CdS core/shell quantum dots with tunable surface composition

Sowers, Kelly L.; Hou, Zhentao; Peterson, Jeffrey J.; Swartz, Brett D.; Pal, Sougata; Prezhdo, Oleg V.; Krauss, Todd D.

doi:10.1016/j.chemphys.2015.09.010

Cited by 39 publications

(44 citation statements)

References 72 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To increase our understanding of the effect of the ZnS shell and how it affects TET and therefore photon upconversion, we performed time-resolved PL (TRPL) of the NCs both with and without PPO. NCs often show multi-exponential decays, even after shell growth 11 , 58 , 59 and a three exponential fit was required to achieve a satisfactory fit to the data. Both amplitude and intensity weighted average lifetimes, τ and τ̄ respectively, were extracted from the fits.…”

Section: Resultsmentioning

confidence: 99%

CdS/ZnS core–shell nanocrystal photosensitizers for visible to UV upconversion

et al. 2017

View full text Add to dashboard Cite

show abstract

Section: Resultsmentioning

confidence: 99%

CdS/ZnS core–shell nanocrystal photosensitizers for visible to UV upconversion

et al. 2017

View full text Add to dashboard Cite

show abstract

“…On the other hand, it decreases to 1.9 × 10 11 s −1 for MUA-NR. It has been noted that localized trap states lead to reduced radiative rates in CdSe@CdS QDs [63]. As has been discussed above, MUA-capping leads to hole-trap surface states, which then reduces the radiative rate of recombination.…”

Section: Photoluminescence Spectroscopymentioning

confidence: 86%

Influence of Surface Ligands on Charge-Carrier Trapping and Relaxation in Water-Soluble CdSe@CdS Nanorods

2020

View full text Add to dashboard Cite

In this study, the impact of the type of ligand at the surface of colloidal CdSe@CdS dot-in-rod nanostructures on the basic exciton relaxation and charge localization processes is closely examined. These systems have been introduced into the field of artificial photosynthesis as potent photosensitizers in assemblies for light driven hydrogen generation. Following photoinduced exciton generation, electrons can be transferred to catalytic reaction centers while holes localize into the CdSe seed, which can prevent charge recombination and lead to the formation of long-lived charge separation in assemblies containing catalytic reaction centers. These processes are in competition with trapping processes of charges at surface defect sites. The density and type of surface defects strongly depend on the type of ligand used. Here we report on a systematic steady-state and time-resolved spectroscopic investigation of the impact of the type of anchoring group (phosphine oxide, thiols, dithiols, amines) and the bulkiness of the ligand (alkyl chains vs. poly(ethylene glycol) (PEG)) to unravel trapping pathways and localization efficiencies. We show that the introduction of the widely used thiol ligands leads to an increase of hole traps at the surface compared to trioctylphosphine oxide (TOPO) capped rods, which prevent hole localization in the CdSe core. On the other hand, steric restrictions, e.g., in dithiolates or with bulky side chains (PEG), decrease the surface coverage, and increase the density of electron trap states, impacting the recombination dynamics at the ns timescale. The amines in poly(ethylene imine) (PEI) on the other hand can saturate and remove surface traps to a wide extent. Implications for catalysis are discussed.

show abstract

“…These defects strongly influence optical and photovoltaic properties of nanomaterials due to formation of states inside the fundamental bandgap. For instance, defects often lead to rapid electron‐phonon energy losses arising from decreased electronic energy gaps and increased electron‐phonon NA coupling . Generally, the NA electron‐phonon coupling is stronger for small/localized systems because it depends on the sensitivity of wave functions to nuclear motion: If wave functions are delocalized, they are less sensitive to system geometry than if they are localized.…”

Section: Photoexcitation Dynamicsmentioning

confidence: 99%

Nonadiabatic charge dynamics in novel solar cell materials

Long

Prezhdo

Fang

2017

WIREs Comput Mol Sci

View full text Add to dashboard Cite

The review describes recent research into the nonequilibrium phenomena in nanoscale materials, with focus on charge separation and recombination, that form the basis for photovoltaic and photocatalytic devices. Nonadiabatic molecular dynamics combined with ab initio real-time time-dependent density functional theory enable us to model time-resolved laser experiments at the atomistic level, emphasizing realistic aspects of the materials, such as defects, dopants, boundaries, chemical bonding, etc. A variety of systems have been considered, including bulk semiconductors sensitized by semiconducting/metallic nanoparticles and graphene, nanocrystal/molecule junctions, polymer interfaces with carbon nanotubes and nanoclusters, van der Waals heterojunctions, black phosphorus, and hybrid organic-inorganic perovskites. The detailed atomistic knowledge obtained from the explicit time-domain modeling generates comprehensive understanding of electron-vibrational dynamics in complex multicomponent systems, provides critical insights into quantum mechanical transport of energy and charge, and leads to valuable guidelines for improvement of solarto-electric power conversion in photovoltaic and photocatalytic applications and for efficient performance of transport devices. FIGURE 14 | Decay of populations of the first excited state in bilayer black phosphorus (BP) and at the BP/MoS 2 interface. BP/MoS 2 shows slower decay because of electron-hole separation across the interface.

show abstract

Photophysical Properties of CdSe/CdS core/shell quantum dots with tunable surface composition

Cited by 39 publications

References 72 publications

CdS/ZnS core–shell nanocrystal photosensitizers for visible to UV upconversion

CdS/ZnS core–shell nanocrystal photosensitizers for visible to UV upconversion

Influence of Surface Ligands on Charge-Carrier Trapping and Relaxation in Water-Soluble CdSe@CdS Nanorods

Nonadiabatic charge dynamics in novel solar cell materials

Contact Info

Product

Resources

About