Tarun Chandel

Electrochemical growth and studies of CuInSe2 thin films

Thin films of CuInSe2 were grown on fluorine doped tin oxide (<10 Ω/) coated glass using the electrodeposition technique. The electrodeposition was carried out potentiostatically using an aqueous bath consisting of solutions of CuCl2, InCl3 and SeO2 with ethylenediamine-dihydrochloride (EDC) added for complexation. CuInSe2 films were also deposited without using any complexing agent in the bath. To improve the crystallinity the CuInSe2 films were annealed in vaccum at 300 °C for one hour. The annealed films were analyzed by x-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive analysis of x-rays (EDAX), atomic force microscopy (AFM) and optical spectra. The results obtained in this work show that by adding a suitable complexing agent to the electrochemical bath, nanocrystalline CuInSe2, 20 nm to 30 nm in size, can be grown. The composition of the CuInSe2 films can be controlled by means of the bath composition and stoichiometric films can be obtained for a bath with ionic Cu:In:Se composition close to 1:4:2. AFM micrographs show that the particles are generally oval shaped for near stoichiometric compositions. However for extreme copper rich layers, the morphology is completely different, the particles in this case appearing in the form of nanoflakes. Each flake has a thickness in the nano range, but the surface extends to a length of several microns.

Growth of nanocrystalline Cu2ZnSnS4 thin films using the spray pyrolysis technique and their characterization

Nanocrystalline thin films of Cu2ZnSnS4 (CZTS) were grown on the glass substrates using the spray pyrolysis technique. The films were grown at a substrate temperature of 300 °C after which they were annealed at 350 °C in vacuum. X-ray diffraction (XRD) studies showed that the films crystallized in the kesterite structure. Energy dispersive analysis of X-rays (EDAX) studies showed that the films possess the desired stoichiometry i.e. the proportion of Cu:Zn:Sn:S in the CZTS solid solution is close to 2:1:1:4. Secondary Ions Mass Spectroscopy (SIMS) depth profiling confirmed the uniformity in elemental composition along the depth of the films. SEM studies showed that the films are covered with CZTS particles forming sheet like structures. AFM studies show that the size of the particles on the surface of the films is around 10-15 nm. UV-VIS-NIR transmission spectra were used to determine the optical band gap of the CZTS films which was found to be around 1.55eV.Nanocrystalline thin films of Cu2ZnSnS4 (CZTS) were grown on the glass substrates using the spray pyrolysis technique. The films were grown at a substrate temperature of 300 °C after which they were annealed at 350 °C in vacuum. X-ray diffraction (XRD) studies showed that the films crystallized in the kesterite structure. Energy dispersive analysis of X-rays (EDAX) studies showed that the films possess the desired stoichiometry i.e. the proportion of Cu:Zn:Sn:S in the CZTS solid solution is close to 2:1:1:4. Secondary Ions Mass Spectroscopy (SIMS) depth profiling confirmed the uniformity in elemental composition along the depth of the films. SEM studies showed that the films are covered with CZTS particles forming sheet like structures. AFM studies show that the size of the particles on the surface of the films is around 10-15 nm. UV-VIS-NIR transmission spectra were used to determine the optical band gap of the CZTS films which was found to be around 1.55eV.

Structural, optical and photoelectric properties of sprayed CdS thin films

In this study, CdS thin films were grown via a facile spray pyrolysis technique. The crystalline phase, morphological, compositional and optical properties of the CdS thin films have been studied using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and UV-vis absorption spectroscopy, respectively. XRD patterns show that the grown CdS films crystallized in the hexagonal structure. Scanning electron microscopy (SEM) study shows that the surfaces of the films are smooth and are uniformly covered with nanoparticles. EDAX results reveal that the grown films have good stochiometry. UV-vis spectroscopy shows that the grown films have transparency above 80% over the entire visible region. The photo-electric response of the CdS films grown on glass substrates has been observed.In this study, CdS thin films were grown via a facile spray pyrolysis technique. The crystalline phase, morphological, compositional and optical properties of the CdS thin films have been studied using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and UV-vis absorption spectroscopy, respectively. XRD patterns show that the grown CdS films crystallized in the hexagonal structure. Scanning electron microscopy (SEM) study shows that the surfaces of the films are smooth and are uniformly covered with nanoparticles. EDAX results reveal that the grown films have good stochiometry. UV-vis spectroscopy shows that the grown films have transparency above 80% over the entire visible region. The photo-electric response of the CdS films grown on glass substrates has been observed.

Synthesis and characterization of spin-coated ZnS thin films

In this paper, we report synthesis of ZnS thin films using a sol-gel method. A unique aprotic solvent, dimethlysulphoxide (DMSO) has been used to obtain a homogeneous ZnS gel. Zinc acetate and thiourea were used as the precursor sources for Zn and S, respectively, to deposit nanocrystalline ZnS thin films. Optical, structural and morphological properties of the films were studied. Optical studies reveal high transmittance of the samples over the entire visible region. The energy band gap (Eg) for the ZnS thin films is found to be about 3.6 eV which matches with that of bulk ZnS. The interference fringes in transmissions spectrum show the high quality of synthesized samples. Strong photoluminescence peak in the UV region makes the films suitable for optoelectronic applications. X-ray diffraction studies reveal that sol-gel derived ZnS thin films are polycrystalline in nature with hexagonal structure. SEM studies confirmed that the ZnS films show smooth and uniform grains morphology having size in 20-25 nm range. The EDAX studies confirmed that the films are nearly stoichiometric.In this paper, we report synthesis of ZnS thin films using a sol-gel method. A unique aprotic solvent, dimethlysulphoxide (DMSO) has been used to obtain a homogeneous ZnS gel. Zinc acetate and thiourea were used as the precursor sources for Zn and S, respectively, to deposit nanocrystalline ZnS thin films. Optical, structural and morphological properties of the films were studied. Optical studies reveal high transmittance of the samples over the entire visible region. The energy band gap (Eg) for the ZnS thin films is found to be about 3.6 eV which matches with that of bulk ZnS. The interference fringes in transmissions spectrum show the high quality of synthesized samples. Strong photoluminescence peak in the UV region makes the films suitable for optoelectronic applications. X-ray diffraction studies reveal that sol-gel derived ZnS thin films are polycrystalline in nature with hexagonal structure. SEM studies confirmed that the ZnS films show smooth and uniform grains morphology having size in 20-25 nm ...

Structural, morphological and optical studies of F doped SnO2 thin films

Highly conducting and transparent FTO (flourine doped tin Oxide) thin films were grown on the glass substrates using a low cost spray pyrolysis technique. The films were characterized for their structural, morphological and optical studies using XRD, SEM and UV-Vis spectroscopy. XRD studies show that the FTO films crystallize in Tetragonal cassiterite structure. Morphological analysis using SEM show that the films are uniformly covered with spherical grains albeit high in surface roughness. The average optical transmission greater than 80% in the visible region along with the appearance of interference fringes in the transmission curves confirms the high quality of the films. Electrical studies show that the films exhibit sheet resistance below 10 Ω ϒ-1.Highly conducting and transparent FTO (flourine doped tin Oxide) thin films were grown on the glass substrates using a low cost spray pyrolysis technique. The films were characterized for their structural, morphological and optical studies using XRD, SEM and UV-Vis spectroscopy. XRD studies show that the FTO films crystallize in Tetragonal cassiterite structure. Morphological analysis using SEM show that the films are uniformly covered with spherical grains albeit high in surface roughness. The average optical transmission greater than 80% in the visible region along with the appearance of interference fringes in the transmission curves confirms the high quality of the films. Electrical studies show that the films exhibit sheet resistance below 10 Ω ϒ-1.

PEDOT: PSS: rGO nanocomposite as a hole transport layer (HTLs) for P3HT:PCBM based organic solar cells

This paper reports the fabrication process of organic solar cell (OSCs) having structure ITO/PEDOT:PSS:rGO/P3HT:PCBM/Al. In this cell, poly (3, 4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS) is ultrasonically mixed with thermally reduced graphene oxide (rGO), which was used as a hole transport layer (HTLs). In order to investigate structural, morphological and optical properties of nanocomposite, XRD, FE-SEM and UV-vis spectroscopy were carried out. We have observed, Jsc = 6.5mA/cm2, Voc = 212 mV, FF=0.31 and PCE of 0.43% from fabricated organic solar cell.This paper reports the fabrication process of organic solar cell (OSCs) having structure ITO/PEDOT:PSS:rGO/P3HT:PCBM/Al. In this cell, poly (3, 4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS) is ultrasonically mixed with thermally reduced graphene oxide (rGO), which was used as a hole transport layer (HTLs). In order to investigate structural, morphological and optical properties of nanocomposite, XRD, FE-SEM and UV-vis spectroscopy were carried out. We have observed, Jsc = 6.5mA/cm2, Voc = 212 mV, FF=0.31 and PCE of 0.43% from fabricated organic solar cell.

Sol-gel derived ZnO as an electron transport layer (ETL) for inverted organic solar cells

In this work, we present the study of the fabrication process of the sol-gel derived zinc oxide (ZnO) as an electron transport layer (ETL.). The solution processed inverted bulk heterojunction organic solar cells based on a thin film blend of poly (3-hexylthiophene 2, 5-diyl) and [6,6]-phenyl-C61-butyric acid methyl ester is prepared. ZnO thin films are annealed at different temperature to optimize the solar cell performance and their characterization for their structural and optical properties are carried out. We have observed Voc=70mV, Jsc=1.33 µA/cm2 and FF=26% from the inverted heterojunction solar cell.

Growth and properties of vacuum evaporated ZnSe thin films

Thin films of ZnSe were obtained on glass substrates in the temperature range 200 °C - 350 °C employing a Vacuum Co-evaporation method under a pressure of 1×106-2×10 6 torr. X-ray diffraction, SEM, AFM and Energy dispersive analysis of X-rays (EDAX) studies were performed to investigate the structural, morphological and compositional properties of the films. The optical properties of the films were also studied and some of the optical constants like refractive index, optical absorption coefficient (a) and optical bandgap (Eg) were determined using the transmission spectra.

Growth and characterization of ZnSe nanoparticles

ZnSe nanoparticles were prepared using a chemical bath deposition technique. X-ray diffraction study shows that the ZnSe crystallizes in the cubic phase. The crystallite size of the ZnSe samples calculated using the Scherrer’s formula was found to be slightly smaller than the Bohr exciton radius of bulk ZnSe. SEM studies show the growth of a mixture of nanorods and spherical nanoparticles. EDAX analysis confirms that the synthesized ZnSe nanoparticles are of good stiochiometry. Optical studies show the blue shift in the absorption edge for ZnSe nanoparticles caused by quantum confinement.