CuInSe2 Powders Research Articles

PREPARATION AND CHARACTERIZATION OF CuInSe2 NANO-PARTICLES

CuInSe2 synthesized by a modified solvothermal route could be altered considerably by controlling the reaction temperature, reaction time and washing agents. Synthesized CuInSe2 powders were characterized by X-ray diffraction. The thermal properties of lattice strain (e), particle size (t), lattice parameters (a, c) and Debye-Waller factor (B) were determined from the half-widths and integrated intensities of the Bragg reflections. CuInSe2 powderwas strained by Temperature values 150 oc, 160 oc, 170 oc, 180 oc, and 190 oc. From a study of X-ray diffractograms recorded at different stages of different temperature values, it is observed that it has a systematic effect on the particle size. The particle shape was spherical when deionized water was used as a washing agent and Particles with the size down to 26.6nm were obtained. When the washing agent changed to ethanol, nano-rods with the diameter ranged from 100 to 200nm and the length of several micrometers were observed in the TEM. The variation of energy of vacancy formation as a function of lattice strain has been studied.

Microstructure and thermoelectric properties of CuInSe2/In2Se3 compound

CuInSe2 powders were synthesized by solvothermal method, and then the CuInSe2/In2Se3 bulk samples were fabricated by spark plasma sintering (SPS) technique. To investigate the phase composition, the powders were determined by X-ray diffraction (XRD). The microstructures of the powders and bulk samples were observed by scanning electron microscopy (SEM). The transportation of the electronic properties and thermal conductivity were measured at room temperature to 700 K. According to the results, the CuInSe2 powders appeared in flower-like patterns which ranged from 3 [Formula: see text]m to 6 [Formula: see text]m. CuInSe2 powders were synthesized at 180[Formula: see text]C with a chalcopyrite structure. The Seebeck coefficient increased significantly in composite thermoelectric materials up to [Formula: see text] at 623 K. The thermal conductivity of the sample significantly decreases from the room temperature to 700 K. The CuInSe2 bulk composite by solvothermal method achieves the highest ZT value of 0.187 at 700 K.

The effects of different technologies on synthesis of CuInSe2 prepared by coreduction.

Solution thermal method was used to synthesize CuInSe2 powders from metal chlorides and SeO2 at 160~200°C. The phases of product samples were analyzed by x-ray diffraction (XRD), the size and morphology of the products were observed by JSM6380LA scanning electron microscope (SEM). The aim is to explore the best technology to obtain the pure CuInSe2 powders. Experimental results show that, CuInSe2 phase can be formed with metal chlorides by reacting for 20 h at 160°C, 180°C and 200°C and has XRD peaks corresponding to (112), (204) and (312) crystal planes, respectively. It consists of irregular spherical grains with about 0.2~0.5 μm in diameter, which agglomerate larger particles with average particle size about 1~3 μm. CuInSe2 phase was formed more easily at the temperature higher than 180°C and shows better crystallinity.

Formation Pathway of CuInSe<sub>2</sub> through Solvothermal Route

CuInSe2 (CIS) is a promising material for thin film solar cell applications. In this work, CIS powders have been synthesized by solvothermal route at different reaction time. X-ray diffraction patterns and Raman spectra of the products reveal that the optimal reaction time is 36 h at 200 °C in order to obtain pure CIS phase. SEM images show an irregular morphology of synthesized CIS material. The formation pathway of CIS has also been studied. Cu-Se compounds are formed at the beginning of the reaction, which act as an important intermediate for the formation of CIS products. This result is not consistent with the reported mechanism.

Solvothermal Synthesis of CuInSe<sub>2</sub> Nanostructured Powders: Comparing Open-Air with Applying Internal Imposed Pressure

Nanocrystalline CuInSe2 (CIS) powders were synthesized with a simple open-air solvothermal method as well as under conditions of applying internal imposed pressure. No post-treating processes such as annealing or selenization were used in both methods. The synthesis processes involved the reaction of precursors in an autoclave for different process times. Structural, morphological, and opto-electronic properties of CIS powders were compared. X-ray diffraction patterns (XRD) confirmed the formation of chalcopyrite structure of CIS powders in both approaches at reaction temperature of 220 °C and for short process time. Field emission scanning electron microscopy (FESEM) results show that while CIS powders synthesized under the atmospheric condition are mostly agglomerated, particles have more specific shapes in samples synthesized under internal imposed pressure. Furthermore, the band gap energies of synthesized CIS powders were obtained using diffuse reflectance UV-vis spectroscopy (DRS) measurements.

Synthesis and Characterization of CuInS<sub>2</sub> and CuInSe<sub>2</sub> Compounds by Vacuum Sintering Method

We report herein synthesis and characterization of CuInS2and CuInSe2compounds by vacuum sintering method. In this study, the manual-milled and ball-milled precursors including copper, indium, and sulfur (selenium) elements were sintered under vacuum at different temperatures for synthesis of CuInS2and CuInSe2compounds, respectively. The crystal structure, morphology and Raman property of the sintered powder were investigated by X-ray diffraction, scanning electron microscope and Raman scattering spectroscopy, respectively. The results show that the structure of the products, which was sintered with the manual-milled and ball-milled precursors, were transformed into the single chalcopyrite phase CuInS2powder at 923K and 623K, and the grain size are about 2～3μm and 250 nm, respectively. In addition, the CuInSe2 powder was synthesized about 723K via using the ball-milled powder including copper, indium, and selenium elements as the precursor.

ChemInform Abstract: Preparation and Characterization of CuInSe2 Particles via the Hydrothermal Route for Thin‐Film Solar Cells.

AbstractWell‐crystallized CuInSe2 powders with chalcopyrite structure are obtained from the hydrothermal reaction of CuCl2, InCl3, Se, NaOH, and triethanolamine (H2O, autoclave, 180 °C, 1 h).

Comprehensive insights into point defect and defect cluster formation in CuInSe2

The concentration of native point defects in CuInSe2 powder material as a function of stoichiometry has been experimentally determined by neutron powder diffraction. A correlation between the Cu/In ratio and the density of VCu as well as InCu has been established and their concentrations are quantified. It is demonstrated, that assuming the spontaneous formation of defect pairs, the density of native point defects is reduced significantly by an order of magnitude. The functionality of a solar device, assuming same conditions like in the analyzed material, may be explained by a neutralization due to the formation of electrically inactive defect complexes.

Preparation and electrical properties of CuInSe2 thin films by pulsed laser deposition using excess Se targets

An effective way to prepare a robust CuInSe2 (CIS) target for subsequent vapor depositions of thin films is suggested in this work. The technique involves addition of excess Se to presynthesized CIS powder followed by cold pressing and sintering at a temperature as low as 300 °C. Phase-pure chalcopyrite CIS films were prepared at a substrate temperature of 300 °C from targets that contained different amounts of excess Se. The average size of particulates, typical of the pulsed laser deposition process, and their surface coverage decreased with increasing Se content up to 50 wt% in the targets. Films grown from the target with 50 wt% excess Se exhibited a hole concentration of ˜3 × 1019 cm−3 and a Hall mobility of ˜2 cm2/Vs. With the decrease of substrate temperature to room temperature, the resistivity increased from 1.1 × 10−1 to ˜7.5 × 108 Ω·cm, which is attributed to the potential contributions of Se interstitials, CuIn, and VIn defects.