Multiple Exciton Dissociation in CdSe Quantum Dots by Ultrafast Electron Transfer to Adsorbed Methylene Blue

Huang, Jier; Huang, Zhuangqun; Yang, Ye; Zhu, Haiming; Lian, Tianquan

doi:10.1021/ja100106z

Cited by 220 publications

(296 citation statements)

References 75 publications

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“…25,30 For the CdS-MV 2+ and CdS-AQ complexes, the recovery of 1S bleach is accompanied by the formation of reduced adsorbates (MV +á and AQ -radicals) signals at ~600 nm and ~630 nm, respectively ( Figure 1D and 1E). 29,[31][32][33] Therefore, the photoinduced ET processes from the excited QDs to adsorbates can be monitored by the kinetics of either the QD (1S exciton bleach recovery) or adsorbate (ground state bleach or radical formation) TA features, as shown in Figure S4.…”

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confidence: 95%

Auger-Assisted Electron Transfer from Photoexcited Semiconductor Quantum Dots

et al. 2014

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Although quantum confined nanomaterials, such as quantum dots (QDs) have emerged as a new class of light harvesting and charge separation materials for solar energy conversion, theoretical models for describing photoinduced charge transfer from these materials remains unclear. In this paper, we show that the rate of photoinduced electron transfer from QDs (CdS, CdSe and CdTe) to molecular acceptors (anthraquinone, methylviologen and methylene blue) increases at decreasing QD size (and increasing driving force), showing a lack of Marcus inverted regime behavior over an apparent driving force range of ~ 0-1.3 V. We account for this unusual driving force dependence by proposing an Auger-assisted electron transfer model, in which the transfer of the electron can be coupled to the excitation of the hole, circumventing the unfavorable Frank-Condon overlap in the Marcus inverted regime. This model is supported by computational studies of electron transfer and trapping processes in model QD-acceptor complexes.

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Auger-Assisted Electron Transfer from Photoexcited Semiconductor Quantum Dots

et al. 2014

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“…Although electronic interactions between QDs and organic molecules have been well established (9,10), often times QDs are coupled to other inorganic species, a pairing which has been elucidated to a lesser extent. Such interactions are fundamentally different from those in QD-molecular systems because inorganic materials possess a continuum of electronic states, as opposed to discrete states inherent to molecular acceptors.…”

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Photoinduced electron transfer from semiconductor quantum dots to metal oxide nanoparticles

Tvrdy

Frantsuzov²,

Kamat

2010

Proc. Natl. Acad. Sci. U.S.A.

623

786

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Quantum dot-metal oxide junctions are an integral part of nextgeneration solar cells, light emitting diodes, and nanostructured electronic arrays. Here we present a comprehensive examination of electron transfer at these junctions, using a series of CdSe quantum dot donors (sizes 2.8, 3.3, 4.0, and 4.2 nm in diameter) and metal oxide nanoparticle acceptors (SnO 2 , TiO 2 , and ZnO). Apparent electron transfer rate constants showed strong dependence on change in system free energy, exhibiting a sharp rise at small driving forces followed by a modest rise further away from the characteristic reorganization energy. The observed trend mimics the predicted behavior of electron transfer from a single quantum state to a continuum of electron accepting states, such as those present in the conduction band of a metal oxide nanoparticle. In contrast with dye-sensitized metal oxide electron transfer studies, our systems did not exhibit unthermalized hot-electron injection due to relatively large ratios of electron cooling rate to electron transfer rate. To investigate the implications of these findings in photovoltaic cells, quantum dot-metal oxide working electrodes were constructed in an identical fashion to the films used for the electron transfer portion of the study. Interestingly, the films which exhibited the fastest electron transfer rates (SnO 2 ) were not the same as those which showed the highest photocurrent (TiO 2 ). These findings suggest that, in addition to electron transfer at the quantum dot-metal oxide interface, other electron transfer reactions play key roles in the determination of overall device efficiency.Marcus theory | transient absorption spectroscopy | quantum dot sensitized solar cell | nanotechnology | energy conversion S emiconducting quantum dots (QDs) are a widely studied material with many interdisciplinary applications (1, 2). Perhaps the most appealing attribute of these materials, from both an academic and industrial perspective, is their size-dependent electronic structure-the ability to design systems and devices with tailor-made electronic properties simply by altering the size of one of the constituent materials (3). As less expensive and less complex routes are continually developed to synthesize a variety of QD materials, further implementation of QDs into nextgeneration devices and procedures is inevitable.The properties of QDs are often exploited in a system or device through their complexation with other materials of interest: functionalizing QDs with biomolecules for imaging (4); linking many QDs together with short-chain molecules to create nanostructured electronic arrays (5); creating highly emissive core-shell QD particles for sensors and optoelectronic displays (6); or sensitizing semiconducting systems with other semiconductors to create inexpensive, next-generation photovoltaic devices (7,8). In each of the aforementioned applications, QDs are utilized because of their size-dependent electronic structure.Although electronic interactions between QDs and organic molecules ...

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“…No entanto, as imagens por luminescência utilizadas nesta seção foram coletadas em posições distantes da região da interface que separa os dois filmes. (SHAW et al, 2010;HUANG et al, 2010). Ainda estamos estudando os efeitos da fase  nos processos de autoaniquilamento do éxciton no PFO.…”

Section: Processos Fotofísicos Nas Proximidades Da Interface Tio 2 /Pfounclassified

Fotogeração, migração e dissociação do éxciton em filmes de Polifluorenos (amorfos e ordenados) próximos de interface orgânica/inorgânica

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Multiple Exciton Dissociation in CdSe Quantum Dots by Ultrafast Electron Transfer to Adsorbed Methylene Blue

Cited by 220 publications

References 75 publications

Auger-Assisted Electron Transfer from Photoexcited Semiconductor Quantum Dots

Auger-Assisted Electron Transfer from Photoexcited Semiconductor Quantum Dots

Photoinduced electron transfer from semiconductor quantum dots to metal oxide nanoparticles

Fotogeração, migração e dissociação do éxciton em filmes de Polifluorenos (amorfos e ordenados) próximos de interface orgânica/inorgânica

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