Effect of shell thickness on electrochemical property of wurtzite CdSe/CdS core/shell nanocrystals

Fan, Kai; Liao, Chen; Xu, Ruilin; Zhang, Huichao; Cui, Yiping; Zhang, Jiayu

doi:10.1016/j.cplett.2015.05.006

Cited by 7 publications

(9 citation statements)

References 29 publications

(68 reference statements)

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“…The sample preparation was conducted within a pure Ar‐filled glove box and the electrochemical cell was thoroughly sealed, because the electrolyte solution should be in deoxygenated atmosphere. [ 23,24 ]…”

Section: Resultsmentioning

confidence: 99%

“…The electrical band gap (

E_{gap}^{e l}

) is larger than the optical band gap (

E_{gap}^{o p t}

) for all QDs because the

E_{gap}^{o p t}

value is related to the

E_{gap}^{e l}

value by

E_{gap}^{o p t} = E_{gap}^{e l} - J_{e, h}

, where J e , h is the Coulomb interaction energy of the electron–hole pair. [ 24,25 ] As a result, the J e , h value of the InP core‐only QDs was estimated to be 0.17 eV and that of both InP/ZnSe/ZnS QDs was approximately ≈0.55 eV. This occurs because the

E_{gap}^{e l}

value in core‐shell‐shell QDs becomes larger due to an activation barrier that the electron should surmount to migrate into the core.…”

Section: Resultsmentioning

confidence: 99%

“…It implies that the electrochemical response includes the properties of external surroundings (shell and ligand) as well as the internal core of the nanocrystal. [ 24 ]…”

Section: Resultsmentioning

confidence: 99%

“…The sample preparation was conducted within a pure Ar-filled glove box and the electrochemical cell was thoroughly sealed, because the electrolyte solution should be in deoxygenated atmosphere. [23,24] Figure 2a displays the fundamental optical properties of InP QDs dispersed in solution. Figure 2b presents the cyclic voltammogram (CV).…”

Section: Fundamental Electrical and Optical Propertiesmentioning

confidence: 99%

“…, where J e,h is the Coulomb interaction energy of the electron-hole pair. [24,25] As a result, the J e,h value of the InP core-only QDs was estimated to be 0.17 eV and that of both InP/ZnSe/ZnS QDs was approximately ≈0.55 eV. This occurs because the E el gap value in core-shell-shell QDs becomes larger due to an activation barrier that the electron should surmount to migrate into the core.…”

Section: Fundamental Electrical and Optical Propertiesmentioning

confidence: 99%

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Electrochemical Charging Effect on the Optical Properties of InP/ZnSe/ZnS Quantum Dots

Park

Won

Kim

et al. 2020

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fabrication of blue-emitting Cd-free QDs are still under development. [7-10] Above all, the charging of QDs is an obstacle for manufacturing QD-LEDs with good performance. [11] The simple mechanism of EL is that electrons and holes are formed by charge injection, and light is generated by the electron-hole pair recombination. Hence, it is essential to understand the charging process by mimicking EL processes. The complementary combination of spectroscopic technology and electrochemical control helps emulate EL and explain the charging process whether the charges occupy quantum states or trap states. Recently, there has been an increase in research to improve QD luminescence capabilities and charge extraction properties by performing electrochemical charging studies on QD films. [1,12,13] Li et al. [13] have shown that electron injection into the ground excitonic state of CdSe/CdS QDs leads to the bleaching of 1S 3/2 1S e transition because of 1S e state filling. Qin et al. [14] have investigated how the photoluminescence (PL) lifetime changes in CdSeS/ZnS QD under electrochemical control with blinking dynamics. Gooding et al. [15] have studied the effects of hole and electron injection on the PL of CdSe/ CdS/ZnS QDs. Many studies have revealed the effect of electron injection on the optical properties in Cd-based QDs, which leads to environmental issues. Environmentally friendly III-V semiconductors, especially InP QDs, have recently emerged as the best alternative to toxic II-VI semiconductors. [16-17] Meanwhile, the surfaces of InP core QDs are easily oxidized when they are exposed to oxygen environments. As a countermeasure, overcoating nanocrystals with wider band-gap materials has proven to be the best option to increase stability against photo-oxidation and to enhance the photoluminescence quantum yield (PL QY). [5,18,19] For example, the inorganic core can be surrounded by the shell, such as ZnSe and ZnS. [20] Möbius et al. reported that the electrical charges generated by application of a mechanical load are injected into the QDs, leading to PL quenching in InP/ZnS-based device. [17] However, the spectroelectrochemical properties were not yet reported in InP QDs to the best of our knowledge. Recently, we have reported highly luminescent InP/ZnSe/ZnS QDs synthesized with as much high efficiency as state-of-the-art Cd-based QDs. [21] In this study, we analyze the spectroelectrochemical properties depending on mid-shell thickness to identify the effect of charging on highly luminescent InP Semiconductor quantum dots (QDs) are spotlighted as a key type of emissive material for the next generation of light-emitting diodes (LEDs). This work presents the investigation of the electrochemical charging effect on the absorption and emission of the InP/ZnSe/ZnS QDs with different mid-shell thicknesses. The excitonic peak is gradually bleached during electrochemical charging, which is caused by 1S e (or 1S h) state filling when the electron (or hole) is injected into the InP core. Additional charges also lead to photo...

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Section: Resultsmentioning

confidence: 99%

“…The electrical band gap (

E_{gap}^{e l}

) is larger than the optical band gap (

E_{gap}^{o p t}

) for all QDs because the

E_{gap}^{o p t}

value is related to the

E_{gap}^{e l}

value by

E_{gap}^{o p t} = E_{gap}^{e l} - J_{e, h}

E_{gap}^{e l}

value in core‐shell‐shell QDs becomes larger due to an activation barrier that the electron should surmount to migrate into the core.…”

Section: Resultsmentioning

confidence: 99%

“…It implies that the electrochemical response includes the properties of external surroundings (shell and ligand) as well as the internal core of the nanocrystal. [ 24 ]…”

Section: Resultsmentioning

confidence: 99%

Section: Fundamental Electrical and Optical Propertiesmentioning

confidence: 99%

Section: Fundamental Electrical and Optical Propertiesmentioning

confidence: 99%

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Electrochemical Charging Effect on the Optical Properties of InP/ZnSe/ZnS Quantum Dots

Park

Won

Kim

et al. 2020

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Role of Copper Doping in Heavy Metal‐Free InP/ZnSe Core/Shell Quantum Dots for Highly Efficient and Stable Photoelectrochemical Cell

Zhao

Cai

et al. 2021

Advanced Energy Materials

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the emerging global energy crisis. [1] To boost the hydrogen production efficiency, the rational design and fabrication of semiconductor photoelectrodes with broad light absorption, adequate exciton generation, efficient charge separation/transfer, and long-term stability are highly desired. [2] Recently, semiconductors quantum dots (QDs) have demonstrated huge potential as light sensitizers in photoanodes for high efficiency solar-driven PEC application due to their size/shape/composition-tunable optical properties that features considerable overlap with solar spectrum. [3] However, the state-of-the-art QDs used in current PEC systems still suffer from major limitations including highly toxic heavy metal elements (Pb, Cd etc.), insufficient charge separation/transfer, and low photo-stability. [1b,4] Developing eco-friendly core/shell structured QDs is a promising strategy to address these issues, while a proper selection of core and shell materials is necessary to obtain core/shell QDs with tailored band structure, optimized optical properties/ charge dynamics, and enhanced photo/chemical stability for high performance and stable solar-to-hydrogen conversion.Among various semiconductor QDs, heavy metal-free InP QDs have recently attracted great attention due to their large absorption coefficient, narrow band gap (≈1.34 eV in bulk), and wide wavelength tunability. [5] Nevertheless, bare InP QDs can exhibit abundant surface defect states, resulting in severe non-radiative recombination for largely reduced quantum yield (QY, usually <5%) and photo/chemical stability. [6] Generally, inorganic shell (such as ZnS and ZnSe) were coated on InP core QDs to form type I band alignment with improved radiative emission and photo/chemical stability. [7] Considering the stress-induced defects at the core/shell interface, the ZnSe shell with a lower lattice mismatch (3.4%) as compared to ZnS (7.6%) is more appropriate to coat on InP core for optimized optical characteristics. [8] In 2019, Jang et al. synthesized InP/ZnSe/ZnS QDs to fabricate a red QDs-light-emitting diode (QLED) with an external quantum efficiency of 21.4%, which is considered as a milestone for the display application based on environmentally friendly QDs, demonstrating the huge potential of InP-based core/shell QDs as building blocks in optoelectronic devices. [9] However, to date, most of the investigations regarding InP-based core-shell QDs are mainly focused on enhancing As emerging eco-friendly alternatives to traditional Cd/Pb-based quantum dots (QDs), InP/ZnSe(S) core/shell QDs have demonstrated huge potential in light-emitting technologies. So far, these QDs have been rarely employed in solar energy conversion applications due to their type-I band structure offering limited photo-induced charge carrier separation and transfer. Here, a controllable Cu shell doping approach is reported to engineer the optoelectronic properties of InP/ZnSe core/shell QDs and realize high performance and stable solar-driven photoelectrochemical (PEC) hydrogen evol...

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Advancements in Ruthenium (Ru)‐Based Heterostructure Catalysts: Overcoming Bottlenecks in Catalysis for Hydrogen Evolution Reaction

Kuang,

Yang,

Feng

2024

Advanced Energy Materials

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Investigating clean and sustainable hydrogen generation from water splitting requires cost‐effective and highly efficient electrocatalysts for the hydrogen evolution reaction (HER). Ruthenium (Ru)‐based heterostructure catalysts have emerged as promising alternatives to precious Pt, offering significant potential to overcome current bottlenecks. Recent advancements in Ru‐based heterostructure catalysts have focused on achieving a balance between catalytic activity and stability. An overview of these developments provides insights into catalytic mechanisms and facilitates the development of novel catalysts. This review begins with an exploration of the enhanced activity of heterostructure catalysts, followed by a critical summary of synthetic strategies employed to fabricate these catalysts and their catalytic performances for HER. Attention is then directed to experimental endeavors aimed at enhancing the HER performance of Ru‐based heterostructure catalysts. Finally, the opportunities and challenges in developing heterostructure catalysts from the perspectives of material design and synthesis are discussed. Through these discussions, a comprehensive understanding of Ru‐based heterostructure catalysts and inspiring future research directions is the aim to provide.

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Effect of shell thickness on electrochemical property of wurtzite CdSe/CdS core/shell nanocrystals

Cited by 7 publications

References 29 publications

Electrochemical Charging Effect on the Optical Properties of InP/ZnSe/ZnS Quantum Dots

Electrochemical Charging Effect on the Optical Properties of InP/ZnSe/ZnS Quantum Dots

Role of Copper Doping in Heavy Metal‐Free InP/ZnSe Core/Shell Quantum Dots for Highly Efficient and Stable Photoelectrochemical Cell

Advancements in Ruthenium (Ru)‐Based Heterostructure Catalysts: Overcoming Bottlenecks in Catalysis for Hydrogen Evolution Reaction

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