EASILY REALIZABLE HETEROJUNCTION CdS/CuInSe2 FOR THIN FILMS PHOTOVOLTAIC APPLICATION (original) (raw)
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Materials Chemistry and Physics, 2011
Herein, we report engineering of nanostructured p-CuIn 3 Se 5 /n-CdS heterojunction thin film on a glass substrate, which is prepared at room temperature using simple wet chemical approach involving ion exchange reactions between CdS and Cu + , In 3+ and Se 2− ions in alkaline medium. The uniform deposition of heterojunction thin films is achieved by optimizing the pH, temperature and molarity of the reactant bath. The as-deposited thin-films were annealed at 200 • C in air for 1 h and further characterized for structural, optical and electrical properties using UV-Vis spectrophotometer, X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), Hall effect for type of conductivity, and I-V measurement to investigate the charge conduction phenomenon. The characteristic (1 1 2) and (1 1 0) planes in XRD and the electron diffraction pattern could confirm the formation of CuIn 3 Se 5. The chemical composition and the band gap energy E g = 1.4 eV of the nanostructured p-CuIn 3 Se 5 /n-CdS heterojunction thin-films were confirmed using XPS and the absorbance spectra, respectively. Based on the data and energy band gap calculations of CuIn 3 Se 5 and CdS thin films, the probable band alignment between the nanostructured p-CuIn 3 Se 5 /n-CdS heterojunction is proposed.
Advances in CuInSe2 and CdTe thin film solar cells
Solar Cells, 1991
Research on CuInSe2 and CdTe thin film solar cells is discussed. CuInSe2 was deposited by selenization of Cu/In layers and was used to make a 109/0 efficient CuInSe2/(CdZn)S cell. Characterization of the reaction mechanisms is described. The open-circuit voltage Voc of CuInSe2/(CdZn)S cells is dominated by recombination in the space charge region, so increasing the band gap or decreasing the width of this region should increase Voc. Increasing the band gap with a thin Cu(InGa)Se2 layer at the CuInSe2 surface has demonstrated increased Voc with collection out to the CuInSe2 band gap. A post-deposition treatment and contacting process for evaporated CdS/CdTe cells was developed and high efficiency cells were made. Several steps in the process, including a CdC12 coating, a 400 °C heat treatment, and a contact containing copper are critical. ZnTe films were deposited from an aqueous solution as a contact to CdTe. 0379-6779/91/$3.50
New Investigations Applied on Cadmium Sulfide Thin Films for Photovoltaic Applications
In this paper we present some new investigations made on nanocrystalline cadmium sulfide thin films used as photoactive components in CdS/CdTe photovoltaic cells. The cadmium sulfide (CdS) thin films were deposited by method of thermal vacuum evaporation, from a single source, on ITO covered optical glass substrates of different thicknesses and electrical resistances. In order to improve the structural and chemical properties of the prepared films, post-deposition thermal treatments combined with chemical treatments based on CdCl 2 vapors were performed on all samples. The transmission as well as the absorption spectra were recorded using a UV-VIS double beam spectrophotometer. From the absorption spectra, the optical band-gaps of the films were calculated. The structural characterization of the cadmium sulfide thin films was made by GIXRD (Grazing Incidence X – Ray Diffraction) for samples of different thicknesses. The morphological investigations were carried out by cross section ...
The photoresponse of CdS/CuInSe2 thin-film heterojunction solar cells
Ieee Transactions on Electron Devices, 1984
The effect of light bias on the spectral current response and spectral capacitance characteristics of CdS/CuInSe2 thin-film heterojunction solar cells has been investigated. Monochromatic light bias has been used to identify specific wavelength regions responsible for the spectral behavior seen under white light bias. Variations with light or voltage bias are consistent with the effect of the field on interface recombination in both high and low CdS resistivity devices. Devices with high CdS resistivity show spectrally dependent enhancement and quenching effects very similar to those reported for CdS/Cu2S devices in which the space charge region was primarily in the CdS. It is concluded that in high CdS resistivity devices the junction behavior is controlled by the photoconductive CdS as has been established in CdS/Cu2S cells. Low CdS resistivity CdS/CuInSe2 devices show none of these effects.
Electrodeposition of n-CdSe/p-Cu2Se Heterojunction Solar Cells
Engineered science, 2020
Thin film heterojunction photovoltaic (PV) solar cells play a vital role due to its large area, low cost and higher efficiency devices in solar energy conversion. In this work, low-temperature and cost-effective electrodeposition of n-CdSe and p-Cu2Se heterojunction solar cells are developed and explored. The individual part of heterojunction is screened for its structure, morphology, compositional, optical, and photoelectrochemical measurements. Then-CdSe/p-Cu2Se device designed onto an indium-tin-oxide conducting substrate with PEDOT layer sequencing followed gold contact for extracting charge carriers referring to appropriate band energy level diagram elucidate solar-cell type, behavior due easy charge transportation process of holes and electrons in a different direction of heterojunction. Despite a low power conversion efficiency due to weak current density and voltage.
Investigation of the Properties of Cadmium Sulphide Thin Films for Solar Cell Applications
The paper presents an investigation of the properties of Cadmium Sulphide (CdS) thin films and their suitability for use as solar cell material. Thin films of cadmium sulphide with thicknesses ranging from 0.8-3.26 µm were deposited on microscope glass slides using the chemical bath deposition method (CBD). The paper also presents some findings on how to optimize the chemical bath deposition technique to achieve improved quality of CdS thin films deposited on glass substrates. Some of the samples were annealed while others were left unannealed. All the samples were tested to investigate the physical, electrical and optical characteristics of the deposited thin films. The physical properties measured were the thickness and surface morphology of the samples. The electrical properties were the resistivity, conductivity type and charge carrier mobility while the optical property was the band gap energy. The resistivity of the samples was measured using the four point probe method while the band gap energy was measured using a UV/VIS spectrophotometer. The unannealed samples were found to have an average resistivity of 1.01217 ×10 3 Ωcm and average band gap energy of 2.493 eV. The average charge carrier mobility of the unannealed samples was 2209.4 cm 2 v-1 s-1 measured based on the Hall Effect principle. From the galvanometer deflection as measured against standard using the hot probe method was observed that CdS is an n-type semiconducting material. Comparing results obtained for both annealed and unannealed samples, it was observed that there is a decrease of 4.63% on resistivity and 0.72% on band gap energy of the annealed samples. The charge carrier mobility increased by 12.3% for the annealed samples as well. The quality of CdS thin film can be improved through annealing. This implies that the thin film developed in the current study could be used as a window layer for heterojunction solar cells of the types; Cadmium sulphide/ Cupper Indium Selenide (CdS/CuInSe 2) or Cadmium Sulphide/ Cadmium Telluride (CdS/CdTe).
Low-cost deposition of CuInSe 2 (CIS) films for CdS/CIS solar cells
Solar Energy Materials and Solar Cells, 1998
We discuss in this paper the development of inexpensive, high efficiency, large-area solar cells of the type thin-film ZnO/CdS/Cu(In,Ga)Se . It has been shown recently in research laboratory tests that polycrystalline thin-film cells of this general composition deposited onto inexpensive soda-lime glass substrates have solar-to-electric conversion efficiencies exceeding 17%. These small-area cells were deposited using vacuum technology which is difficult and expensive to scale up in area to square-meter flat-plate modules in a manufacturing arena. We discuss in this paper inexpensive, non-vacuum deposition technology which is inherently scalable to largearea deposition. We pay particular attention to electrodeposition of multilayer binary or ternary selenide precursors to be thermally annealed to form Cu(In,Ga)Se films of appropriate overall composition, elemental grading and smoothness.