Two-step synthesis of high-quality water-soluble near-infrared emitting quantum dots via amphiphilic polymers

Zhao, Haiguang; Wang, Defa; Zhang, Teng; Chaker, Mohamed; Ma, Dongling

doi:10.1039/c0cc00067a

Cited by 82 publications

(126 citation statements)

References 18 publications

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“…As previously reported, the shell of PbS@CdS QDs is mainly composed of CdS. 20,21 The average overall diameter of the pure PbS QDs or the core@shell QDs was estimated from TEM images. As-synthesized PbS and core@shell QDs exhibit a very well dened rst-exciton absorption peak and PL peak.…”

Section: Synthesis and Structure Of Pbs@cds Core@shell Qdsmentioning

confidence: 92%

“…1g and h. The core size was estimated from the exciton absorption peak. 21 The overall QD diameter (d total ), core diameter (d core ), CdS shell thickness (d shell ), the maximum absorbance and PL peaks are listed in Table 1. The pure PbS and core@shell PbS@CdS QDs range from 3 nm to 6 nm with a typical QY of 19-85% in toluene, a <9% size distribution and a lifetime of 1-3 ms, indicating that our synthesis yields good quality QDs, consistent with the PbS QDs reported in the literature.…”

Section: Synthesis and Structure Of Pbs@cds Core@shell Qdsmentioning

confidence: 99%

“…The pure PbS and core@shell PbS@CdS QDs range from 3 nm to 6 nm with a typical QY of 19-85% in toluene, a <9% size distribution and a lifetime of 1-3 ms, indicating that our synthesis yields good quality QDs, consistent with the PbS QDs reported in the literature. 20,21 In fact, even with very thin shell, around 0.1-0.3 nm, the QY and stability of plain PbS QDs can be largely enhanced. 20,24 The electron transfer behavior of PbS@CdS QDs was investigated by loading QDs on mesoporous thin lms prepared by standard tape casting oxide paste onto transparent glass substrates.…”

Section: Synthesis and Structure Of Pbs@cds Core@shell Qdsmentioning

confidence: 99%

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Controlling photoinduced electron transfer from PbS@CdS core@shell quantum dots to metal oxide nanostructured thin films

et al. 2014

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N-type metal oxide solar cells sensitized by infrared absorbing PbS quantum dots (QDs) represent a promising alternative to traditional photovoltaic devices. However, colloidal PbS QDs capped with pure organic ligand shells suffer from surface oxidation that affects the long term stability of the cells.Application of a passivating CdS shell guarantees the increased long term stability of PbS QDs, but can negatively affect photoinduced charge transfer from the QD to the oxide and the resulting photoconversion efficiency (PCE). For this reason, the characterization of electron injection rates in these systems is very important, yet has never been reported. Here we investigate the photoelectron transfer rate from PbS@CdS core@shell QDs to wide bandgap semiconducting mesoporous films using photoluminescence (PL) lifetime spectroscopy. The different electron affinity of the oxides (SiO 2 , TiO 2 and SnO 2 ), the core size and the shell thickness allow us to fine tune the electron injection rate by determining the width and height of the energy barrier for tunneling from the core to the oxide.

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Section: Synthesis and Structure Of Pbs@cds Core@shell Qdsmentioning

confidence: 92%

Section: Synthesis and Structure Of Pbs@cds Core@shell Qdsmentioning

confidence: 99%

Section: Synthesis and Structure Of Pbs@cds Core@shell Qdsmentioning

confidence: 99%

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Controlling photoinduced electron transfer from PbS@CdS core@shell quantum dots to metal oxide nanostructured thin films

et al. 2014

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“…Compared with the control devices made with P3HT and PCBM mixtures, the power conversion efficiency of the hybrid cells increased by approximately 18 %, due to the enhanced absorption and transportation of photoexcited charges related to the QDs and MWCNTs, respectively. Considering the stability issue of plain PbS QDs and significantly improved photo-and thermal-stability of the PbS/CdS core-shell QDs, [66,[89][90][91] it is interesting to explore the use of these coreshell QDs in solar cells. One negative factor, however, could be the inefficient charge transfer in these seemingly type-I QDs, where, unlike in type-II QDs, the shell may serve as a barrier for charge transfer.…”

Section: Hybrid Polymer-qd Solar Cellsmentioning

confidence: 99%

Semiconductor and Metallic Core–Shell Nanostructures: Synthesis and Applications in Solar Cells and Catalysis

Kim

Chen

et al. 2014

Chemistry A European J

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Nano-heterostructures have attracted great attention due to their extraordinary properties beyond those of their single-component counterparts. This review focuses on a specific type of hybrid structures: core-shell structures. In particular, we present and discuss the recent wet-chemical synthesis approaches for semiconductor and metallic core-shell nanostructures, and their relevant properties and potential applications in photovoltaics and catalysis, respectively.

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“…然而, 由于有机金属热解法制备的量子点表面存在大量的悬键和缺陷 [7] , 以及常用有机配体 (如三辛基硫膦、油酸等)对量子点表面钝化不足 [8] , 使得光致电子发生非辐射耦合, 降低了量子点的光学性能 [9] . 同时, 这些悬键和缺陷还会导致量子点表面发生光氧化、光漂白和光降解反应, 降低了量子点的稳定性 [10] .…”

Section: 引言unclassified

Utilizing Cation Exchange Method to Produce Core/Shell PbS/CdS Quantum Dots with Stable Infrared Emission

李谦¹,

张腾²,

古宏伟³

et al. 2013

Acta Chim. Sinica

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PbS quantum dots (QDs) have enormous potential for applications ranging from tunable infrared lasers to solar cells due to their efficient emission over a large spectral range in the infrared. Especially, multiple exciton generation has been observed in PbS QDs, which makes PbS QDs have great potential for high-efficiency solar cells. However, these applications have been limited by instability in emission quantum yield and peak position on exposure to ambient conditions. An effective strategy to improve PbS QDs' stability is overgrowth with a shell of a more stable semiconductor, such as CdS, resulting in core/shell PbS/CdS QDs. The PbS/CdS QDs were fabricated in a two-step method. In the first step, PbS QDs with a 4.8 nm diameter were prepared by using organic metal. Second, PbS/CdS QDs with 3.8 nm PbS core and 0.5 nm CdS shell were fabricated by exposing PbS QDs in Cd 2＋ solution for 24 h at 65 ℃. In this article, cation exchange method was adopted to moderate reaction temperature in a low temperature, so that Ostwald ripening in high temperature was avoided. The results of transmission electron microscopy (TEM) and high resolution TEM showed that PbS QDs were sphere and in a cubic cystal without obvious lattice defects. After PbS QDs being cation exchanged, PbS/CdS QDs' size and crystalline form almost kept the same. The results of X-ray diffraction also showed both the crystalline form of PbS and PbS/CdS QDs were cubic. That PbS/CdS QDs had strong absorption and bright photo fluorescence in near infrared region was proved in UV/Vis/NIR and PL spectrum. The stability was proved by comparing fresh QDs' and 3 months later QDs' PL spectrum, in which little blue shift and decrease in PL intensity was found in PbS/CdS QDs. Besides, the results showed that the degree of cation exchange was limited on the surface of the QDs. For example, 0.5 nm CdS shell was formed on the surface of PbS QDs after being exchanged for 24 h in 65 ℃. Thin as CdS shell was, it could effectively passivate PbS QDs' surface defects and significantly improve the photooxidation stability. By employing cation exchange method, highly crystallized core/shell PbS/CdS QDs with superior and stable infrared emission were fabricated at a low temperature.

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Two-step synthesis of high-quality water-soluble near-infrared emitting quantum dots via amphiphilic polymers

Cited by 82 publications

References 18 publications

Controlling photoinduced electron transfer from PbS@CdS core@shell quantum dots to metal oxide nanostructured thin films

Controlling photoinduced electron transfer from PbS@CdS core@shell quantum dots to metal oxide nanostructured thin films

Semiconductor and Metallic Core–Shell Nanostructures: Synthesis and Applications in Solar Cells and Catalysis

Utilizing Cation Exchange Method to Produce Core/Shell PbS/CdS Quantum Dots with Stable Infrared Emission

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