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Facile microwave-assisted synthesis of Klockmannite CuSe nanosheets and their exceptional electrical properties.

Liu YQ, Wang FX, Xiao Y, Peng HD, Zhong HJ, Liu ZH, Pan GB - Sci Rep (2014)

Bottom Line: This is ascribed to the quantum size effect of NS and the presence of Schottky barrier.In addition, the influence of the molar ratio of Cu(2+)/SeO2, reaction temperature, and reaction time on the growth of CuSe NSs is explored.The template effect of oleylamine and the intrinsic crystal nature of CuSe NS are proposed to account for the growth of hexagonal CuSe NSs.

View Article: PubMed Central - PubMed

Affiliation: Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 215123 Suzhou, P. R. China.

ABSTRACT
Klockmannite copper selenide nanosheets (CuSe NSs) are synthesized by a facile microwave-assisted method and fully characterized. The nanosheets have smooth surface and hexagonal shape. The lateral size is 200-500 nm × 400-800 nm and the thickness is 55 ± 20 nm. The current-voltage characteristics of CuSe NS films show unique Ohmic and high-conducting behaviors, comparable to the thermally-deposited gold electrode. The high electrical conductivity of CuSe NSs implies their promising applications in printed electronics and nanodevices. Moreover, the local electrical variation is observed, for the first time, within an individual CuSe NS at low bias voltages (0.1 ~ 3 V) by conductive atomic force microscopy (C-AFM). This is ascribed to the quantum size effect of NS and the presence of Schottky barrier. In addition, the influence of the molar ratio of Cu(2+)/SeO2, reaction temperature, and reaction time on the growth of CuSe NSs is explored. The template effect of oleylamine and the intrinsic crystal nature of CuSe NS are proposed to account for the growth of hexagonal CuSe NSs.

No MeSH data available.


(a) Schematic illustration and (b) representative SEM image of a device based on CuSe NSs film. (c) I–V characteristics of CuSe NSs film before and after pyridine treatment. (d) I–V characteristics of thermally-deposited Au electrode.
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f6: (a) Schematic illustration and (b) representative SEM image of a device based on CuSe NSs film. (c) I–V characteristics of CuSe NSs film before and after pyridine treatment. (d) I–V characteristics of thermally-deposited Au electrode.

Mentions: To explore the electrical properties of CuSe NSs, a prototype device is fabricated (Fig. 6a). The device is fabricated by dropping 20 μL CuSe NS solution onto pre-patterned Au electrodes. The solvent is dried by vacuum-annealing at 40°C for 30 min. It can be seen that CuSe NSs are interconnected and stack into a compact film (Fig. 6b). Fig. 6c shows the typical current-voltage (I-V) characteristics of the device. The observation of almost linear response demonstrates an Ohmic rather than semiconducting behavior of CuSe NSs. Note that the device with pyridine treatment shows more excellent electrical conductivity than that without pyridine treatment. At a bias voltage of 500 mV, currents of about 10−5 and 10−2 A are recorded for the devices before and after pyridine treatment, respectively. This is a substantial increase in current by about three orders of magnitude. As discussed previously4041, the original OM adsorbed on CuSe NSs could be removed with pyridine treatment and consequently the charge mobility in NS thin film is improved significantly. The effect of pyridine is similar to short hydrocarbon ligands such as mercaptopropionic acid, ethylenediamine, and ethanedithiol, which are used to reduce inter-particle distance and enhance inter-particle coupling9. The high-conducting behavior is further explored by measuring the Hall Effect in the pyridine-treated CuSe NS film with the thickness of ~20 μm. The results show that the CuSe NS film resides in the P-type conduction. The hole mobility and the carrier density give the values of 1.87 cm2 V−1 s−1 and 3.01 × 1021/cm3, respectively, which is comparable with vapor-deposited Cu2-xSe thin films42. Moreover, the conductivity of pyridine-treated CuSe NS film is almost identical to that of thermally-deposited Au electrode (Fig. 6d). The above results enlighten us to develop a novel and promising low-cost semiconductor material in place of traditional noble metals (Au, Ag, Cu et al) for high-performance electronic conductors. In addition, in view of the band gap of CuSe NSs (Fig. 3b), the photoconductivity of CuSe NS thin film is also investigated. It is unexpected that the current shows no obvious changes before and after illumination (Fig. S8). This could be due to the intrinsic high carrier concentration of CuSe NSs, which may depress the changes in photo-excited carriers upon illumination9.


Facile microwave-assisted synthesis of Klockmannite CuSe nanosheets and their exceptional electrical properties.

Liu YQ, Wang FX, Xiao Y, Peng HD, Zhong HJ, Liu ZH, Pan GB - Sci Rep (2014)

(a) Schematic illustration and (b) representative SEM image of a device based on CuSe NSs film. (c) I–V characteristics of CuSe NSs film before and after pyridine treatment. (d) I–V characteristics of thermally-deposited Au electrode.
© Copyright Policy - open-access
Related In: Results  -  Collection

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f6: (a) Schematic illustration and (b) representative SEM image of a device based on CuSe NSs film. (c) I–V characteristics of CuSe NSs film before and after pyridine treatment. (d) I–V characteristics of thermally-deposited Au electrode.
Mentions: To explore the electrical properties of CuSe NSs, a prototype device is fabricated (Fig. 6a). The device is fabricated by dropping 20 μL CuSe NS solution onto pre-patterned Au electrodes. The solvent is dried by vacuum-annealing at 40°C for 30 min. It can be seen that CuSe NSs are interconnected and stack into a compact film (Fig. 6b). Fig. 6c shows the typical current-voltage (I-V) characteristics of the device. The observation of almost linear response demonstrates an Ohmic rather than semiconducting behavior of CuSe NSs. Note that the device with pyridine treatment shows more excellent electrical conductivity than that without pyridine treatment. At a bias voltage of 500 mV, currents of about 10−5 and 10−2 A are recorded for the devices before and after pyridine treatment, respectively. This is a substantial increase in current by about three orders of magnitude. As discussed previously4041, the original OM adsorbed on CuSe NSs could be removed with pyridine treatment and consequently the charge mobility in NS thin film is improved significantly. The effect of pyridine is similar to short hydrocarbon ligands such as mercaptopropionic acid, ethylenediamine, and ethanedithiol, which are used to reduce inter-particle distance and enhance inter-particle coupling9. The high-conducting behavior is further explored by measuring the Hall Effect in the pyridine-treated CuSe NS film with the thickness of ~20 μm. The results show that the CuSe NS film resides in the P-type conduction. The hole mobility and the carrier density give the values of 1.87 cm2 V−1 s−1 and 3.01 × 1021/cm3, respectively, which is comparable with vapor-deposited Cu2-xSe thin films42. Moreover, the conductivity of pyridine-treated CuSe NS film is almost identical to that of thermally-deposited Au electrode (Fig. 6d). The above results enlighten us to develop a novel and promising low-cost semiconductor material in place of traditional noble metals (Au, Ag, Cu et al) for high-performance electronic conductors. In addition, in view of the band gap of CuSe NSs (Fig. 3b), the photoconductivity of CuSe NS thin film is also investigated. It is unexpected that the current shows no obvious changes before and after illumination (Fig. S8). This could be due to the intrinsic high carrier concentration of CuSe NSs, which may depress the changes in photo-excited carriers upon illumination9.

Bottom Line: This is ascribed to the quantum size effect of NS and the presence of Schottky barrier.In addition, the influence of the molar ratio of Cu(2+)/SeO2, reaction temperature, and reaction time on the growth of CuSe NSs is explored.The template effect of oleylamine and the intrinsic crystal nature of CuSe NS are proposed to account for the growth of hexagonal CuSe NSs.

View Article: PubMed Central - PubMed

Affiliation: Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 215123 Suzhou, P. R. China.

ABSTRACT
Klockmannite copper selenide nanosheets (CuSe NSs) are synthesized by a facile microwave-assisted method and fully characterized. The nanosheets have smooth surface and hexagonal shape. The lateral size is 200-500 nm × 400-800 nm and the thickness is 55 ± 20 nm. The current-voltage characteristics of CuSe NS films show unique Ohmic and high-conducting behaviors, comparable to the thermally-deposited gold electrode. The high electrical conductivity of CuSe NSs implies their promising applications in printed electronics and nanodevices. Moreover, the local electrical variation is observed, for the first time, within an individual CuSe NS at low bias voltages (0.1 ~ 3 V) by conductive atomic force microscopy (C-AFM). This is ascribed to the quantum size effect of NS and the presence of Schottky barrier. In addition, the influence of the molar ratio of Cu(2+)/SeO2, reaction temperature, and reaction time on the growth of CuSe NSs is explored. The template effect of oleylamine and the intrinsic crystal nature of CuSe NS are proposed to account for the growth of hexagonal CuSe NSs.

No MeSH data available.