Alloyed (ZnSe)x(CuInSe2)1–x and CuInSexS2–x Nanocrystals with a Monophase Zinc Blende Structure over the Entire Composition Range

Li, Shenjie; Zhao, Zechen; Liu, Qinghui; Huang, Lizhen; Wang, Gang; Pan, Daocheng; Zhang, Hongjie; He, Xingquan

doi:10.1021/ic201083r

Cited by 47 publications

(38 citation statements)

References 39 publications

(84 reference statements)

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“…The small variation of a VBM potential at lower x value than 0.5 is because of the relatively large bandgap bowing of (ZnSe) x (CIGS) 1-x material system. The results for both the lattice parameter and the VBM are similar to those reported for (ZnSe) x (CuInSe 2 ) 1-x by Li et al, and for (ZnS) x (CuGaS 2 ) 1-x by Quintans et al [36,37] It should be noted that the Mott-schottky plots revealed that the flat-band potential of (ZnSe) 0.89 (CIGS) 0.11 is about 0.2 V higher than that of CIGS indicating the about 0.2 V deeper VBM potential of (ZnSe) 0.89 (CIGS) 0.11 than that of CIGS. (see Figure S12 in the Supporting Information) The variation of the VBM potential between (ZnSe) 0.89 (CIGS) 0.11 and CIGS estimated by Mott-Schottky plots are consistent with PESA results.…”

supporting

confidence: 89%

A Novel Photocathode Material for Sunlight‐Driven Overall Water Splitting: Solid Solution of ZnSe and Cu(In,Ga)Se₂

Kaneko

Minegishi

Nakabayashi

et al. 2016

Adv Funct Materials

105

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content; a similar effect has been found for other material systems. [21][22][23] As shown in Scheme 1, for a solid solution of ZnSe and CIGS, the VBM is expected to be deeper than that for CIGS, and the absorption edge longer than that for ZnSe. In this work, we investigated the PEC properties of (ZnSe) x (CIGS) 1-x thin-film photocathodes. The VBM was 0.25 V deeper than that for CIGS, and the onset potential was 0.89 V RHE , which is 0.17 V higher than that for CIGS. This higher onset potential allows PEC cells to be fabricated with a variety of photoanodes without the need for an external bias voltage. [24][25][26][27] Moreover, (ZnSe) 0.85 (CIGS) 0.15 contains much less of the rare metals indium and gallium. Therefore, (ZnSe) 0.85 (CIGS) 0.15 offers advantages over CIGS from the viewpoint of large-scale applications.Using a (ZnSe) 0.85 (CIGS) 0.15 photocathode with a BiVO 4 photoanode, [28] PEC overall water splitting without the need for an external bias voltage was demonstrated. The two-electrode cell produced stoichiometric amounts of H 2 and O 2 under simulated sunlight. The maximum STH was 0.91%, which is one of the highest values reported for a PEC cell containing a photoanode and a photocathode. [4] Results and Discussion PEC Properties of (ZnSe) 0.85 (CIGS) 0.15 PhotocathodesCurrent density versus potential curves for Pt and Pt/CdS modified (ZnSe) 0.85 (CIGS) 0.15 photocathodes are shown in Figure 1a. This composition was found to produce the largest photocurrent at 0.5 V RHE , as discussed in the next section.Whereas the photocathode modified by Pt alone showed a small cathodic photoresponse, the photocathode modified with both Pt and CdS exhibited a large photocurrent density of 6.5 mA cm −2 at 0 V RHE with a relatively high onset potential of 0.81 V RHE , which was defined as a cathodic photocurrent density of 0.05 mA cm −2 . It has been reported that an n-type CdS layer enhances the degree of charge separation by forming a p-n junction at the solid-liquid interface with the underlying p-type layer, which leads to a larger photocurrent and a higher onset potential because of the change in the band alignment. [29,30] As shown in Figure S1 (Supporting Information), the Pt/CdS/(ZnSe) 0.85 (CIGS) 0.15 photocathode showed no decay in the photocurrent at 0.1 V RHE over a period of more than 1 h. Such stable hydrogen evolution from water is similar to that reported for photocathodes based on chalcopyrites. [30][31][32] The incident photon to current conversion efficiency (IPCE) spectrum shown in Figure 1b indicates that the absorption edge is located around 900 nm. Despite the relatively high fraction of ZnSe, whose absorption edge is about 460 nm, the absorption edge for (ZnSe) 0.85 (CIGS) 0.15 is close to that for CIGS (≈1100 nm). Thus, due to its bandgap and onset potential, (ZnSe) 0.85 (CIGS) 0.15 is the promising material for sunlightdriven hydrogen production from water.Furthermore, insertion of 3-nm-thick Mo and Ti layers between the Pt and CdS improves the photocurrent around the onset potentia...

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supporting

confidence: 89%

A Novel Photocathode Material for Sunlight‐Driven Overall Water Splitting: Solid Solution of ZnSe and Cu(In,Ga)Se₂

Kaneko

Minegishi

Nakabayashi

et al. 2016

Adv Funct Materials

105

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“…Analysis of the PXRD pattern indicates a cubic-like crystal structure for the synthesized nanocrystals. 26 The measured peak locations for the 111, 220, and 311 planes are located between those of CuInS 2 and ZnS, as expected for the alloy material according to Vegard's law. 27 The interplanar spacings calculated from the XRD have been confirmed using the fast Fourier transform (FFT) diffractogram from the HRTEM image (see S.I.).…”

supporting

confidence: 70%

Synthesis of (CuInS₂)_0.5(ZnS)_0.5 Alloy Nanocrystals and Their Use for the Fabrication of Solar Cells via Selenization

Graeser¹,

Hages²,

Yang³

et al. 2014

Chem. Mater.

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As solar cell absorber materials, alloys of CuIn(S,Se) 2 and Zn(S,Se) provide an opportunity to reduce the usage of indium along with the ability to tune the band gap. Here we report successful synthesis of alloyed (CuInS 2 ) 0.5 (ZnS) 0.5 nanocrystals by a method that solely uses oleylamine as the liquid medium for synthesis. The reactive sintering of a thin film of these nanocrystals via selenization at 500 °C results in a uniform composition alloy (CuIn(S,Se) 2 ) 0.5 (Zn(S,Se)) 0.5 layer with micron size grains. Due to the large amount of zinc in the film, the sintered grains exhibit the zinc blende (sphalerite) structure instead of the usual chalcopyrite structure of CuIn(S,Se) 2 films. The use of the selenide films as a p-type absorber layer has yielded solar cells with total area power conversion efficiencies as high as 6.7% (7.4% based on active area). These preliminary results are encouraging and indicate that with further optimization this class of materials has promise as the absorber layer in solar cells.Chalcogenide materials have received significant attention as absorbers for thin film photovoltaic devices. Notably, materials such as CuIn x Ga 1-x Se 2 (CIGSe) 1-6 and CdTe 7 have been successfully used for this purpose and currently provide the most efficient thin-film solar cells. 8 However, recent efforts have focused on reducing the use of costly elements, such as indium and tellurium, in favor of more earth-abundant, lowcost alternatives. To this end, the Cu 2 ZnSn(S z Se 1-z ) 4 (CZTSSe) material system 9-14 has received increased attention for its potential role as a viable earth-abundant alternative to CIGSe and CdTe absorbers, though to-date this technology has been unable to reach the performance level of the best performing CIGSe and CdTe devices.An alternative technology that can be employed for reducing the use of indium in photovoltaic absorbers is the (CuInSe 2 ) y (ZnSe) 1-y (CZISe) material system, where ternary chalcopyrite CuInSe 2 is alloyed with binary cubic zinc blende ZnSe. This alloying has the potential to decrease the net use of indium in the absorber layer. In this alloy material system, the optical band gap of the absorber can be adjusted from 1.05 eV 15 to 3.7 eV 16 by controlling the degree of alloying between CuInSe 2 and ZnSe, as well as through partial or complete substitution of selenium with sulfur. Additionally, the structure of the CZISe alloy can be shifted from tetragonal chalcopyrite to cubic zinc blende by increasing the ratio of ZnSe to CuInSe 2 in the final film. 17 The simpler crystal structure could make the device processing for this material to be more robust. ZnSe is an n-type semiconductor, while CuInSe 2 is a p-type semiconductor; thus, control of ZnSe and CuInSe 2 alloying can potentially lead to control of the defect characteristics of the absorber layer. These attributes could allow for this material system to reach the performance of the best CZTSSe and CIGSSe devices. This material system has previously been utilized for a variety of semiconduct...

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“…The ZnSe shell may provide higher efficiencies than the ZnS shell since ZnSe has a relatively small, 2% lattice mismatch with CISe, 36 while the lattice mismatch for CISe–ZnS is ∼7%. 24 A lattice mismatch between core and shell materials can prevent the passivation of surface traps, which hamper the bright PL.…”

Section: Results and Disscussionmentioning

confidence: 99%

Highly Luminescent, Size- and Shape-Tunable Copper Indium Selenide Based Colloidal Nanocrystals

et al. 2013

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We report a simple, high-yield colloidal synthesis of copper indium selenide nanocrystals (CISe NCs) based on a silylamide-promoted approach. The silylamide anions increase the nucleation rate, which results in small-sized NCs exhibiting high luminescence and constant NC stoichiometry and crystal structure regardless of the NC size and shape. In particular, by systematically varying synthesis time and temperature, we show that the size of the CISe NCs can be precisely controlled to be between 2.7 and 7.9 nm with size distributions down to 9–10%. By introducing a specific concentration of silylamide-anions in the reaction mixture, the shape of CISe NCs can be preselected to be either spherical or tetrahedral. Optical properties of these CISe NCs span from the visible to near-infrared region with peak luminescence wavelengths of 700 to 1200 nm. The luminescence efficiency improves from 10 to 15% to record values of 50–60% by overcoating as-prepared CISe NCs with ZnSe or ZnS shells, highlighting their potential for applications such as biolabeling and solid state lighting.

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Alloyed (ZnSe)_x(CuInSe₂)_1–x and CuInSe_xS_2–x Nanocrystals with a Monophase Zinc Blende Structure over the Entire Composition Range

Cited by 47 publications

References 39 publications

A Novel Photocathode Material for Sunlight‐Driven Overall Water Splitting: Solid Solution of ZnSe and Cu(In,Ga)Se₂

A Novel Photocathode Material for Sunlight‐Driven Overall Water Splitting: Solid Solution of ZnSe and Cu(In,Ga)Se₂

Synthesis of (CuInS₂)_0.5(ZnS)_0.5 Alloy Nanocrystals and Their Use for the Fabrication of Solar Cells via Selenization

Highly Luminescent, Size- and Shape-Tunable Copper Indium Selenide Based Colloidal Nanocrystals

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Alloyed (ZnSe)x(CuInSe2)1–x and CuInSexS2–x Nanocrystals with a Monophase Zinc Blende Structure over the Entire Composition Range

Cited by 47 publications

References 39 publications

A Novel Photocathode Material for Sunlight‐Driven Overall Water Splitting: Solid Solution of ZnSe and Cu(In,Ga)Se2

A Novel Photocathode Material for Sunlight‐Driven Overall Water Splitting: Solid Solution of ZnSe and Cu(In,Ga)Se2

Synthesis of (CuInS2)0.5(ZnS)0.5 Alloy Nanocrystals and Their Use for the Fabrication of Solar Cells via Selenization

Highly Luminescent, Size- and Shape-Tunable Copper Indium Selenide Based Colloidal Nanocrystals

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Product

Resources

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Alloyed (ZnSe)_x(CuInSe₂)_1–x and CuInSe_xS_2–x Nanocrystals with a Monophase Zinc Blende Structure over the Entire Composition Range

A Novel Photocathode Material for Sunlight‐Driven Overall Water Splitting: Solid Solution of ZnSe and Cu(In,Ga)Se₂

A Novel Photocathode Material for Sunlight‐Driven Overall Water Splitting: Solid Solution of ZnSe and Cu(In,Ga)Se₂

Synthesis of (CuInS₂)_0.5(ZnS)_0.5 Alloy Nanocrystals and Their Use for the Fabrication of Solar Cells via Selenization