A new simple route for the preparation of nanosized copper selenides under different conditions

This article appeared in a journal published by Elsevier. The attachedcopy is furnished to the author for internal non-commercial researchand education use, including for instruction at the authors institution

and sharing with colleagues.

Other uses, including reproduction and distribution, or selling orlicensing copies, or posting to personal, institutional or third party

websites are prohibited.

In most cases authors are permitted to post their version of thearticle (e.g. in Word or Tex form) to their personal website orinstitutional repository. Authors requiring further information

regarding Elsevier’s archiving and manuscript policies areencouraged to visit:

http://www.elsevier.com/authorsrights

http://www.elsevier.com/authorsrights

Author's personal copy

CERAMICSINTERNATIONAL

Available online at www.sciencedirect.com

Ceramics International 40 (2014) 8173–8182

A new simple route for the preparation of nanosized copper selenides underdifferent conditions

Azam Sobhania, Masoud Salavati-Niasarib,n

aDepartment of Chemistry, Kosar University of Bojnord, Bojnord, Islamic Republic of IranbInstitute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box. 87317-51167, Islamic Republic of Iran

Received 21 December 2013; received in revised form 29 December 2013; accepted 3 January 2014Available online 23 January 2014

Abstract

In this paper copper selenide nanostructures were synthesized via a simple hydrothermal method based on the reaction between copper salt andSeCl4 in water. The reduction reaction of SeCl4 to Se and then Se2� was carried out by three types of reductants: N2H4.H2O, KBH4, and metallicZn. Different compositions of copper selenides were obtained by changing the molar ratio of the precursors. At the temperature of 120 1C for a12 h period of time, when the molar ratio of Cu/Se is 1:1 or 2:1, the product is pure and found to be CuSe and Cu1.8Se, respectively. A mixture ofthe different phases of copper selenides is obtained by making use of 1:2, 3:2 and 3:1 M ratios between Cu and Se. With an increasing reactiontemperature up to 210 1C, the mixture of Cu3Se2 and CuSe is prepared from 1:1 M ratio of precursors. The effects of copper salt, surfactant,amount of hydrazine, reaction time and temperature on the morphology and particle size of products are also investigated. The synthesis can beperformed conveniently and safely. The products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM),transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) analysis. Photoluminescence (PL) is used to study theoptical property of copper selenides.& 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Keywords: B. Electron microscopy; B. Grain size; C. Chemical properties; C. Optical properties

1. Introduction

Extensive attention has been paid to the preparation andcharacterization of metal selenides owing to their interestingproperties and potential applications [1–7]. Copper selenidesare semiconductors with p-type conductivity, and have exten-sively been studied due to their potential applications in solarcells [8–10], optical filters and superionic materials. Compar-ing with other promising metallic selenides, copper selenideshave more stoichiometries and phases [11]. Different stoichio-metric (α-Cu2Se, Cu3Se, CuSe and CuSe2) and nonstoichio-metric (Cu2�xSe) compositions and structural forms of themare well-documented. It has been reported that the thermalstability and the band gap of copper selenides vary dependingon their stoichiometries or phases [12,13].

A number of methods for the synthesis of copper selenideshave been explored, such as the mechanical alloying [14],gamma-irradiation [15], microwave [16], ultrasonic synthesis[17,18], hydrothermal [19], vacuum evaporation [20], electrodeposition [21], sol–gel [22], solid-state [23] and solution-phasechemical reaction [24]. Traditionally, bulk copper selenide can beprepared by heating Cu and Se powders at high temperature inflowing Ar. The composition and the crystal structure of the finalproducts are usually dependent on the preparation methods [25–27]. However, the preparation methods and size or shape controlof copper selenides are less flexible than other metal selenidessuch as CdSe, and the studies relating to their optical propertiesare limited. Therefore, it is necessary to develop new methods forpreparing and controlling the size and shape of copper selenidenanostructures.Herein, we report a hydrothermal process for the preparation

of copper selenide nanostructures. Some papers have reportedon the synthesis of the copper selenides via hydrothermal route

www.elsevier.com/locate/ceramint

0272-8842/$ - see front matter & 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.http://dx.doi.org/10.1016/j.ceramint.2014.01.013

nCorresponding author. Tel.: þ98 361 5555 333; fax: þ98 361 555 29 30.E-mail address: [email protected] (M. Salavati-Niasari).


[19], but until now, SeCl4 has not been used as a Se source inthese routes, and effects of different agents together on themorphology, the particle size and the phase of the productshave not been investigated. In this research, we presentthe results of our perfect experiments on the dependence ofthe morphology, particle size, and phase of the products on thekind of Cu salt, surfactant, molar ratio of Cu and Se, kind andamount of reductant, reaction time and temperature. We alsopropose a mechanism for the synthesis of copper selenides.

2. Experimental

2.1. Materials

All the chemicals used in our experiments were of analyticalgrade, were purchased from Merck and were used as receivedwithout further purification. A Teflon-lined stainless steelcylindrical closed chamber with 150 ml capacity was usedfor the synthesis.

2.2. Physical measurements

XRD patterns were collected from a diffractometer ofPhilips Company with X'PertPro monochromatized Cu Kαradiation (λ¼1.54 Å). Microscopic morphology of productswas visualized by a LEO 1455VP scanning electron microscope.TEM image was obtained on a Philips EM208S transmissionelectron microscope with an accelerating voltage of 100 kV.EDS analysis with 20 kV accelerated voltage was done. Roomtemperature photoluminescence was studied on a Perkin Elmer(LS 55) fluorescence spectrophotometer.

2.3. Synthesis of copper selenide nanostructures

In a typical procedure, CuCl2.2H2O was dissolved in water,then a certain amount of cetyltrimethyl ammonium bromide(CTAB) was added under stirring followed by adding SeCl4.The original molar ratio between CuCl2.2H2O and SeCl4 wasselected to be 1:2, 1:1, 3:2, 2:1 and 3:1. After stirring thesolution for 15 min, 2 ml hydrazine was added drop-wise.Finally, the mixture was transferred into a Teflon-linedstainless steel container, then was sealed and maintained at120 1C for 12 h. When the reaction was completed, theproducts were filtered and washed with water followed byabsolute ethanol, then were dried in vacuum before characteriza-tion. Some control experiments, in which CuCl2.2H2O, CTAB,hydrazine and its amount, temperature 120 1C and time 12 h werereplaced by other salts, surfactants, reductants, temperatures andtimes, and other operational processes were unchanged, wereperformed. The results have been listed in Table 1.

3. Results and discussion

3.1. Effect of the molar ratio of Cu and Se in the precursors

In this work, a series of experiments were performed bychanging the molar ratio of CuCl2.2H2O and SeCl4. The XRDpatterns in Figs. 1 and 2 indicate that the copper selenides withvarious phases are produced from different ratios of thereactants. When the molar ratio of Cu/Se is high low (1:2),the product is hexagonal CuSe and a little cubic CuSe2, asshown in Fig. 1a. The peaks which have been indexed withgreen (or star) and orange colors in Fig. 1 indicate the CuSe2and CuSe, respectively. When the molar ratio of Cu/Se is 1:1,

Table 1The reaction conditions of copper selenides synthesized in this work.

Sample no. Cu salt Cu:Se Surfactant Time (h) T (1C) Reductant agent Morphology Size

1 CuCl2.2H2O 1:2 CTAB 12 120 N2H4.H2O (2 ml) Hexagonal nanoparticles 4 100 nm2 CuCl2.2H2O 1:1 CTAB 12 120 N2H4.H2O (2 ml) Hexagonal nanoparticles 4 50 nm3 CuCl2.2H2O 3:2 CTAB 12 120 N2H4.H2O (2 ml) Semi-spherical nanoparticles � 50 nmþmicrostructures4 CuCl2.2H2O 2:1 CTAB 12 120 N2H4.H2O (2 ml) Semi-spherical nanoparticles 50�300 nm5 CuCl2.2H2O 3:1 CTAB 12 120 N2H4.H2O (2 ml) Semi-spherical nanoparticles � 50 nm6 Cu(ClO4)2.6H2O 1:1 CTAB 12 120 N2H4.H2O (2 ml) Coalesced particles �7 CuSO4.5H2O 1:1 CTAB 12 120 N2H4.H2O (2 ml) Hexagonal nanoparticles Non uniform8 Cu(CH3COO)2.H2O 1:1 CTAB 12 120 N2H4.H2O (2 ml) Nanoparticles o 100 nm9 Cu(NO3)2.3H2O 1:1 CTAB 12 120 N2H4.H2O (2 ml) Nanoparticles Uneven10 CuCl2.2H2O 1:1 CTAB 12 180 N2H4.H2O (2 ml) Coalesced particles and bulk structures Microstructures11 CuCl2.2H2O 1:1 CTAB 12 210 N2H4.H2O (2 ml) Hexagons Non uniform12 CuCl2.2H2O 1:1 CTAB 18 180 N2H4.H2O (2 ml) Coalesced particles Microstructures13 CuCl2.2H2O 1:1 CTAB 24 180 N2H4.H2O (2 ml) Coalesced particles Microstructures14 CuCl2.2H2O 1:1 CTAB 12 120 N2H4.H2O (4 ml) Aggregated nanoparticles � 100 nm15 CuCl2.2H2O 1:1 CTAB 12 120 N2H4.H2O (6 ml) Aggregated nanoparticles � 100 nm16 CuCl2.2H2O 1:1 PEG4000 12 180 N2H4.H2O (2 ml) Hexagonal and spherical nanoparticles 150�450 nm17 CuCl2.2H2O 1:1 PEG4000 12 180 Zn Nanoparticlesþrod-like structures Length of 750 nm�2.5 mm18 CuCl2.2H2O 1:1 PEG4000 12 180 KBH4 Rod-like structures Length of 1�3 mm19 CuCl2.2H2O 1:1 � 12 180 N2H4.H2O (2 ml) Spherical and hexagonal nanoparticles Uneven20 CuCl2.2H2O 1:1 PVA 12 180 N2H4.H2O (2 ml) Spherical and hexagonal nanoparticles Uneven21 CuCl2.2H2O 1:1 PEG600 12 180 N2H4.H2O (2 ml) Spherical and hexagonal nanoparticles Uneven

A. Sobhani, M. Salavati-Niasari / Ceramics International 40 (2014) 8173–81828174


the product is found to be pure CuSe (Fig. 1b). The mixture ofcubic Cu1.8Se and tetragonal Cu3Se2 is obtained by making useof a higher molar ratio (3:2) as shown in Fig. 2a. When themolar ratio increases up to 2:1, the product is pure cubicCu1.8Se (space group: Fm-3m) with cell constantsa¼b¼c¼0.576 nm (Fig. 2b). With the molar ratio of 3:1,apart from Cu1.8Se, some cubic Cu2O was also produced dueto the increase of Cu content (Fig. 2c). The peaks which havebeen indexed with black, red (or star) and blue (or .) colors inFig. 2 indicate the Cu1.8Se, Cu3Se2 and Cu2O, respectively.Changing of the ratio of Cu/Se from 1:2 to 1:1 and then 3:2,crystallinity of the as-prepared products is increased. Withmore increase of copper content in molar ratios of 2:1 and 3:1(Cu:Se), crystallinity of the products is decreased.

Fig. 3 shows the morphologies of the products obtained withdifferent molar ratios of the precursors. From the images, it canbe seen that agglomerated nanoparticles with different shapeshave been formed after the synthesis in all samples. The size ofthe nanoparticles decreases regularly with increasing coppercontent. At the temperature of 120 1C for a 12 h period of timeand in the presence of hydrazine and CTAB, when the molarratio of Cu/Se is 1:2 (sample no. 1) or 1:1 (sample no. 2),hexagonal nanoparticles are formed (Fig. 3a and b). Increasingcopper content in samples nos. 3, 4 and 5, with molar ratios of3:2, 2:1 and 3:1 (Cu/Se), respectively, semi-spherical nano-particles are formed (Fig. 3c–e). Figs. 1–3 show that the molarratio of Cu/Se in the precursors plays an important role in thephase transformation, morphology and particle size of copperselenides.

EDS measurements provide further information for theevaluation of the composition and purity of copper selenides.In the EDS spectra of samples nos. 2 and 4 as shown in Fig. 3fand g, the characteristic peaks of Cu and Se are observed,which indicate the formation of pure copper selenides.

3.2. Effect of the copper salt precursors

The morphologies of samples prepared from differentcopper salts in the presence of CTAB and hydrazine at120 1C for 12 h have been characterized by SEM and shownin Fig. 4. The SEM images reveal that morphology and particlesize of products change when different copper salts are used.The product obtained from perchlorate salt (sample no. 6) iscoalesced particles as shown in Fig. 4a. Whereas, in the case ofsample no. 7 which is obtained by sulfate salt, hexagonalassemblies of nanoparticles are formed (Fig. 4b). The nano-particles are also formed when acetate (sample no. 8) andnitrate (sample no. 9) salts are used. According to Fig. 4cand d, with a change at the metal salt from acetate to nitrate,the size and agglomeration of the nanoparticles are increased.The sample no. 8 with a grain diameter less of 100 nm hasnearly even distribution, whereas the sample no. 9 has unevengrain diameter.

3.3. Effect of the reaction temperature

In our experiments, the hexagonal nanoparticles are obtainedin the presence of CTAB and hydrazine at 120 1C for 12 h, as

Fig. 1. XRD patterns of prepared samples from CuCl2.2H2O and SeCl4 in the presence of CTAB and hydrazine at 120 1C for 12 h with different ratios of Cu/Se:(a) 1:2 (sample no. 1) and (b) 1:1 (sample no. 2). (For interpretation of the references to color in this figure, the reader is referred to the web version of this paper.)

A. Sobhani, M. Salavati-Niasari / Ceramics International 40 (2014) 8173–8182 8175


shown in Fig. 3b. On increasing the reaction temperature from120 1C to 180 1C (Fig. 5a), coalesced particles and bulkstructures are formed. With an increase of temperature up to210 1C in sample no. 11, hexagonal copper selenides withlarger diameters are formed (Fig. 5b). The crystallization of thehexagons obtained at 210 1C was characterized by XRD(Fig. 5c). The peaks which have been indexed with red andorange (or star) colors in this figure indicate the Cu3Se2 andCuSe, respectively. In the case of product prepared at 120 1C(sample no. 2), XRD pattern in Fig. 1b shows that CuSe is theonly crystalline phase present. With an increasing reactiontemperature up to 210 1C, the product is found to be themixture of hexagonal Cu3Se2 and cubic CuSe. In our experi-mental conditions, the ideal temperature for the synthesis ofCuSe is 120 1C, because at this temperature pure CuSe withmore favored morphology is formed.

3.4. Effect of the reaction time

Figs. 5a and 6a and b depict SEM images of thecopper selenides in the presence of CTAB and hydrazine at180 1C for 12, 18 and 24 h, respectively. These images revealthe formation of coalesced particles in these three differentperiods of time. With increasing reaction time, the size of thesestructures is decreased.

3.5. Effect of the amount of hydrazine

The SEM images of the as-prepared samples at 120 1C for12 h in the presence of CTAB and different amounts ofhydrazine (samples nos. 2, 14 and 15) have been shown inFigs. 3b and 6c and d, respectively. Fig. 3b shows the SEMimage of copper selenide prepared in the presence of 2 ml

Fig. 2. XRD patterns of prepared samples from CuCl2.2H2O and SeCl4 in the presence of CTAB and hydrazine at 120 1C for 12 h with different ratios of Cu/Se: (a)3:2 (sample no. 3), (b) 2:1 (sample no. 4), and (c) 3:1 (sample no. 5). (For interpretation of the references to color in this figure, the reader is referred to the webversion of this paper.)



Fig. 3. SEM images and EDS patterns of samples prepared from CuCl2.2H2O and SeCl4 in the presence of CTAB and hydrazine at 120 1C for 12 h with differentratios of Cu/Se (a) 1:2, (b) 1:1, (c) 3:2, (d) 2:1, (e) 3:1, (f) 1:1, and (g) 2:1.



hydrazine. In this figure, hexagonal nanoparticles with unevendiameters can be observed. With increasing the amount ofhydrazine from 2 to 4 and 6 ml, semi-spherical nanoparticleswith nearly even distribution are formed, that is their agglom-eration and growing are lower than those of the sample no. 2.

3.6. Effect of the reductant

In continuation, the effect of the sort of reductant on themorphology of the copper selenides in the presence ofpolyethylene glycol (PEG4000) was investigated. Fig. 7 showsthat the reductant plays a key role in the morphology and size,and therefore the properties, of copper selenides. Among someof the chemical reducing agents the borohydrides, hydrazine,citrates and alcohols are commonly used. Different reducingagents have different reducing abilities that influence the rateof reductions. Therefore, one of the advantages of employingchemical reducing agent is that varying the preparationcondition can control the formation of the products. Apartfrom this, only a small amount is needed to complete areaction. In this study, three reducing agents were applied thatinclude N2H4.H2O, Zn and KBH4. The reduction with KBH4

and N2H4.H2O proceed in a homogeneous way, the metalcation solution and the reductant solution are liquid, but thereduction of the liquid metal cation solution with the solid Znpowder is a heterogeneous process being limited by theinterface area of the Zn surface and the solution in contactwith this surface. The strong reductant hydrazine, in combina-tion with stirring rapidly, creates a large number of nuclei andso further growth of the nuclei is limited. As a result, in our

reaction conditions many small particles are obtained (tem-perature 180 1C, time 12 h and in the presence of PEG4000)that are hexagon in shape, as shown in Fig. 7a. In the presenceof Zn, the rate of reduction is further limited by the masstransport of the metal cation solution to the Zn surface.Therefore, depletion of metal cations near the interface mightoccur. As a consequence of the rate and surface area limitation,crystal growth is favored over nucleus formation as the resultof larger particles [28]. In our reaction conditions and in thepresence of Zn, particles elongated along the c-axis and rod-like structures are formed. In the presence of KBH4 (sampleno. 18) the rod-like shape is preferential morphology as shownin Fig. 7e.The XRD patterns of samples prepared in the presence of

hydrazine, Zn and KBH4 are depicted in Fig. 7b, d and f,respectively. The products obtained in the presence of hydra-zine (sample no. 16) are CuSe and CuSe2. With exchange ofreductant agent from hydrazine to Zn (sample no. 17) andKBH4 (sample no. 18), the samples are found to be the mixtureof Se and CuSe2. The diffraction peaks at 29.8˚, 32.8˚, 36.1˚,49.4˚, 54˚ and 56.2˚ in the XRD patterns in Fig. 7 (indexedwith ▼) can be indexed to the (200), (210), (211), (311), (230)and (321) planes of CuSe2, respectively. Obviously, theproduct is made of hexagonal CuSe (in case of sample no.16) or Se (in case of samples nos. 17 and 18) with little CuSe2at 180 1C for 12 h and in the presence of PEG4000 and threetype reductants. So, the reductant hydrazine is not substituteddue to its suitable reducing ability.The detailed morphology of the copper selenides was further

analyzed with TEM. Fig. 8a and b shows the TEM images of

Fig. 4. SEM images of samples prepared in the presence of CTAB and hydrazine at 120 1C for 12 h from different copper salts: (a) Cu(ClO4)2.6H2O (sample no. 6),(b) CuSO4.5H2O (sample no. 7), (c) Cu(CH3COO)2.H2O (sample no. 8) and (d) Cu(NO3)2.3H2O (sample no. 9).



sample prepared in the presence of PEG4000 and 2 mlhydrazine at 180 1C for 12 h (sample no. 16). From theimages, we can see that the particles prepared under these

conditions are hexagonal nanoparticles with diameters in therange 150–450 nm, and also nearly spherical nanoparticleswith diameters of about 30 nm.

Fig. 5. SEM images and XRD pattern of samples prepared from CuCl2.2H2O and SeCl4 in the presence of CTAB and hydrazine at different temperatures for 12 h:(a) 180 1C (sample no. 10), (b) and (c) 210 1C (sample no. 11). (For interpretation of the references to color in this figure, the reader is referred to the web version ofthis paper.)

Fig. 6. SEM images of samples prepared from CuCl2.2H2O and SeCl4 in the presence of CTAB and: (a) 2 ml hydrazine at 180 1C for 18 h (sample no. 12), (b) 2 mlhydrazine at 180 1C for 24 h (sample no. 13), (c) 4 ml hydrazine at 120 1C for 12 h (sample no. 14), and (d) 6 ml hydrazine at 120 1C for 12 h (sample no. 15).



Fig. 8c shows EDS pattern of sample no. 16. In the pattern,only the characteristic peaks of Cu and Se are observed, whichindicate the formation of pure copper selenide.

3.7. Effect of the surfactant

Figs. 5, 7a and 9a–c show the SEM images of thecopper selenides prepared in the presence of different surfac-tants (samples nos. 10, 16, 19, 20 and 21, respectively). It canbe observed that nearly spherical and hexagonal nanoparticleswith different diameters are formed at 180 1C for 12 h, in thepresence of hydrazine and different surfactants.

3.8. Optical properties

One of the impressive features of semiconductors is theirability to emit light. Upon excitation with wavelength shorteror equivalent to the absorption onset, an electron is promoted

from the valance band to the conduction band and uponrelaxation a phonon of light is emitted. Copper selenides arewell known as a p-type semiconductor possessing a directband gap (Eg), as well as an indirect band gap [29]. However,their band gap value varies with the change of their stoichio-metry or phase. The room temperature PL spectra of thecopper selenides in ethanol (Fig. 10) show relatively narrowGaussian distributed curves signifying a monodispersed parti-cles population. The emission maximum of copper selenides atan excitation wavelength of 250 nm is located at 400 nm insample no. 2, while in the case of sample no. 4, it is observedat 425 nm. The difference in the optical properties of twosamples prepared from various molar ratios of Cu/Se is notsurprising because sample no. 2 is hexagonal CuSe, whereassample no. 4 is agglomerated Cu1.8Se with quasi-sphericalmorphology. The optical properties of semiconductor nanoparti-cles are different from those of the corresponding bulk material.The most striking feature of these particles is the increase in the

Fig. 7. SEM images and XRD patterns of samples prepared from CuCl2.2H2O and SeCl4 at 180 1C for 12 h, in the presence of PEG4000 and different reductants:(a) and (b) hydrazine (sample no. 16), (c) and (d) Zn (sample no. 17), (e) and (f) KBH4 (sample no. 18) (▼¼CuSe2).



optical band gap due to the quantum confinement effect observedwhen the size of the particle is comparable to the size of the Bohrexciton radius of the material. This increase in the band gap isobserved as a blue shift in the absorption spectra. Using the PLspectra in Fig. 10, band gaps of about 3.1 and 2.9 eV are obtainedfor CuSe (sample no. 2) and Cu1.8Se (sample no. 4), respectively.These values are higher than the reported band gaps of 2.0–2.2 eVof CuSe [30] and 1.0–1.4 eV of Cu2�xSe [31], and are blue-shifted compared to the bulk samples.

3.9. Reaction mechanism

In our experiment, when SeCl4 is added in the deionized water,a completely clear acidic solution is obtained that contains H2SeO3.We have considered and checked a mechanism for the reaction.This possibility is that H2SeO3 is reduced to elemental Se duringthe first step by hydrazine quickly upon heating solution. Theelemental Se has high reactivity and is easy to be disproportionate

into Se2– ion under alkaline conditions. The Se2� ion reacts withCu2þ ion during the next step to form different phases ofcopper selenides. The proposed mechanism for the synthesis ofcopper selenides can be expressed in the following equations:

SeCl4þ3H2O-H2SeO3þ4HCl (1)

H2SeO3þN2H4.H2O-Se↓þN2↑þ3H2O (2)

3Seþ6OH–-2Se2–þSeO32–þ3H2O (3)

Cu2þþSe2–-CuSe↓ (4)

CuSeþSe-CuSe2↓ (5)

Cu2SeþCuSe-Cu3Se2↓ (6)

Fig. 8. (a) and (b) TEM images and (c) EDS pattern of sample prepared at 180 1C for 12 h and in the presence of PEG4000 (sample no. 16).

Fig. 9. SEM images of samples prepared from CuCl2.2H2O and SeCl4 at 180 1C for 12 h and: (a) in the absent of surfactant (sample no. 19), (b) in the presence ofpolyvinyl alcohol (PVA) (sample no. 20), (c) in the presence of PEG600 (sample no. 21).



4. Conclusion

In summary, copper selenide semiconductors were successfullyproduced by a hydrothermal method. A variety of synthesisparameters, such as kind of Cu salt, surfactant, reductant, molarratio of Cu and Se, reaction time and temperature, have asignificant effect on the particle size, phase purity and morphologyof the obtained products. In our reaction conditions the hydrazine isnot substituted due to its suitable reducing ability. A little Se as animpurity is obtained in the presence of Zn and KBH4. This methodis proved to be an efficient and quick way. SeCl4 and Cu salt assimple precursors have been utilized.

Acknowledgment

Authors are grateful to the Council of University of Kashanfor providing financial support to undertake this work.

References

[1] M. Esmaeili-Zare, M. Salavati-Niasari, A. Sobhani, Simple sonochemicalsynthesis and characterization of HgSe nanoparticles, Ultrason. Sono-chem 19 (2012) 1079–1086.

[2] M. Salavati-Niasari, M. Esmaeili-Zare, A. Sobhani, Synthesis andcharacterisation of cadmium selenide nanostructures by simple sono-chemical method, Micro Nano Lett 7 (2012) 831–834.

[3] M. Salavati-Niasari, M. Esmaeili-Zare, A. Sobhani, Cubic HgSe nano-particles: sonochemical synthesis and characterisation, Micro Nano Lett 7(2012) 1300–1304.

[4] A. Sobhani, M. Salavati-Niasari, Sodium dodecyl benzene sulfonate-assisted synthesis through a hydrothermal reaction, Mater. Res. Bull 47(2012) 1905–1911.

[5] A. Sobhani, F. Davar, M. Salavati-Niasari, Synthesis and characterizationof hexagonal nano-sized nickel selenide by simple hydrothermal methodassisted by CTAB, Appl. Sur. Sci 257 (2011) 7982–7987.

[6] A. Sobhani, M. Salavati-Niasari, F. Davar, Shape control of nickelselenides synthesized by a simple hydrothermal reduction process,Polyhedron 31 (2012) 210–216.

[7] M. Salavati-Niasari, A. Sobhani, Effect of nickel salt precursors onmorphology, size, optical property and type of products (NiSe or Se) inhydrothermal method, Optical Mater 35 (2013) 904–909.

[8] S.T. Lakshmikvmar, A.C. Rastogi, Selenization of Cu and In thin filmsfor the preparation of selenide photo-absorber layers in solar cells usingSe vapour source, Sol. Energy Mater. Sol. Cells 32 (1994) 7–19.

[9] S. Menezes, J. Kessler, D. Schmid, H.W. Schock, R.J. Matson, Use of n-type (Cu2Se)x(In2Se3)1�x ordered defect chalcopyrite films for solar cellabsorber layers, Sol. Energy Mater. Sol. Cells 41 (1996) 325–334.

[10] S.C. Park, D.Y. Lee, B.T. Ahn, K.H. Yoon, J. Song, Fabrication ofCuInSe2 films and solar cells by the sequential evaporation of In2Se3 andCu2Se binary compounds, Sol. Energy Mater. Sol. Cells 69 (2001)99–105.

[11] Powder Diffraction File, Inorganic Phases, Alphabetical Index, JCPDS,PA, 1985, pp. 264, 671.

[12] R.D. Heyding, The copper/selenium system, Can. J. Chem. 44 (1966)1233–1236.

[13] A. Schafer, M. Kouwitz, R. Ahlrichs, Electronic excitation energies incopper selenide clusters, J. Chem. Phys. 104 (1996) 7113–7122.

[14] T. Ohtani, M. Motoki, K. Koh, K. Ohshima, Synthesis of binary copperchalcogenides by mechanical alloying, Mater. Res. Bull. 30 (1995)1495–1504.

[15] Z.P. Qiao, Y. Xie, J.G. Xu, X.M. Liu, Y.J. Zhu, Y.T. Qian, Synthesis ofnanocrystalline Cu2�xSe at room temperature by γ-irradiation, Can. J.Chem. 78 (2000) 1143–1146.

[16] J. Zhu, O. Palchik, S. Chen, A. Gedanken, Microwave assisted prepara-tion of CdSe, PbSe, and Cu2–xSe nanoparticles, J. Phys. Chem. B 104(2000) 7344–7347.

[17] T. Ohtani, T. Nonaka, M. Araki, Sonochemical synthesis of copper andsilver chalcogenides, J. Solid State Chem. 138 (1998) 131–134.

[18] Y. Xie, X.W. Zheng, X.C. Jiang, J. Lu, L.Y. Zhu, Sonochemicalsynthesis and mechanistic study of copper selenides Cu2�xSe, β-CuSe,and Cu3Se2, Inorg. Chem. 41 (2002) 387–392.

[19] S. Xu, H. Wang, J.J. Zhu, H.Y. Chen, Sonochemical synthesis ofcopper selenides nanocrystals with different phases, J. Cryst. Growth234 (2002) 263–266.

[20] M. Kemmler, M. Lazell, P. O'Brien, D.J. Otway, J.H. Park, J.R. Walsh,The growth of thin films of copper chalcogenide films by MOCVD andAACVD using novel single-molecule precursors, J. Mater. Sci.: Mater.Electron. 13 (2002) 531–535.

[21] C. Ricardo, L. Cristina, O. Marco, G. Paula, S. Ricardo, R. Rodrigo,Electrosynthesis of Cu�Se films on copper electrodes in alkaline media:a voltammetric, electrochemical quartz crystal microbalance and I/ttransient study, J. Phys. Chem. B 109 (2005) 3212–3221.

[22] V.S. Gurin, A.A. Alexeenko, S.A. Zolotovskaya, K.V. Yumashev,Copper and copper selenide nanoparticles in the sol–gel matrices:structural and optical, Mater. Sci. Eng. C 26 (2006) 952–955.

[23] C. Kaito, A. Nonaka, S. Kimura, N. Suzuki, Y. Saito, Size effect onsolid–solid reaction growth between Cu film and Se particles, J. Cryst.Growth 186 (1998) 386–392.

[24] R.S. Mane, S.P. Kajve, C.D. Lokhande, S.H. Han, Studies on p-typecopper (I) selenide crystalline thin films for hetero-junction solar cells,Vacuum 80 (2006) 631–635.

[25] W.Z. Wang, P. Yan, F.Y. Liu, Y. Xie, Y. Geng, Y.T. Qian, Preparationand characterization of nanocrystalline Cu2–xSe by a novel solvothermalpathway, J. Mater. Chem. 8 (1998) 2321–2322.

[26] Z.H. Han, Y.P. Li, H.Q. Zhao, S.H. Yu, X.L. Yin, Y.T. Qian, A simplesolvothermal route to copper chalcogenides, Mater. Lett. 44 (2000)366–369.

[27] H.L. Su, Y. Xie, Z.P. Qiao, Y.T. Qian, Formation of Cu2�xSe(en)2 in asolvothermal process and conversion to nanocrystalline Cu2�xSe, Mater.Res. Bull. 35 (2000) 1129–1135.

[28] A. Trifonova, M. Wachtler, M.R. Wagner, H. Schroettner,Ch. Mitterbauer, F. Hofer, K.-C. Möller, M. Winter, J.O. Besenhard,Influence of the reductive preparation conditions on the morphology andon the electrochemical performance of Sn/SnSb, Solid State Ionics 168(2004) 51–59.

[29] A.M. Hermann, L. Fabick, Research on polycrystalline thin-film photo-voltaic devices, J. Cryst. Growth 61 (1983) 658–664.

[30] H.-L Li, Y.-C Zhu, S. Avivi, O. Palchik, J.-p Xiong, Y. Koltypin,V. Palchik, A. Gedanken, Sonochemical process for the preparation of α-CuSe nanocrystals and flakes, J. Mater. Chem. 12 (2002) 3723–3727.

[31] K.L. Chopra, S.R. Das, Thin Film Solar Cells, Plenum, New York, 1983.

Fig. 10. PL spectra of samples prepared from CuCl2.2H2O and SeCl4 with themolar ratios of 1:1 (sample no. 2) and 2:1 (sample no. 4) at 120 1C for 12 h andin the presence of CTAB and hydrazine.


A new simple route for the preparation of nanosized copper selenides under different conditions

Documents

Transcript of A new simple route for the preparation of nanosized copper selenides under different conditions