CdS Thin Film Solar Cells Research Articles

Solution‐Processed Pure Sulfide Cu2(Zn0.6Cd0.4)SnS4 Solar Cells with Efficiency 10.8% Using Ultrathin CuO Intermediate Layer

Herein, it is demonstrated that incorporating ultrathin p‐type cupric oxide (CuO) enhances the performance and stability of solution‐processed Cu2(Zn0.6Cd0.4)SnS4 (CZCTS)/CdS thin film solar cells. In sol–gel CZCTS/CdS thin film solar cells, nanoscale CuO films (4–32 nm) are deposited on top of molybdenum (Mo) by magnetron sputtering and this is used as an intermediate layer (IL). The CuO IL thickness has a significant effect on the short‐circuit current density (JSC) in CZCTS/CdS solar cell devices. As a result, a maximum power conversion efficiency (PCE) of 10.77% is measured for the optimized device with 4 nm CuO compared with 10.03% for the reference device without a CuO layer. Furthermore, the stability of the devices is enhanced significantly by incorporating the CuO IL. This work demonstrates that through proper design of the CuO IL thickness, both the back interface quality and optical property of the CZCTS absorber can be tuned to enhance the device performance.

Photoresponse of novel mixed metal chalcogenide MoSb2-x Cux Se4 /CdS thin film solar cells fabricated by CBD method using citric acid

Photoresponse of novel mixed metal chalcogenide MoSb_2-x Cu_x Se₄ /CdS thin film solar cells fabricated by CBD method using citric acid

MICROSTRUCTURE ANALYSIS OF CDTE/CDS THIN-FILM SOLAR CELLS FOR OPTIMIZATION OF DEVICES FABRICATED AT LOW TEMPERATURE WITH PULSED LASER DEPOSITION

Low temperature fabrication of CdTe (1.25 μm)/CdS (120 nm) thinfilm solar cells was explored using in situ pulsed laser deposition (PLD) in order to control the CdTe grain morphology, crystallinity, and CdS/CdTe interface, which have proven to be crucial in CdTe/CdS solar cell performance. A comparative study was carried out on solar cells fabricated using PLD with the CdTe layer either grown directly at 400°C or at200°C followed with in situ annealing at 400°C for 5-40 minutes in 20 Torr Ar. The post annealed CdTe films exhibit better crystalline characteristics confirmed by optical transmittance and atomic force microscopy as well as improved CdTe/CdS p-n junction, which results in increasingly higher open circuit voltage and fill factor with increasing anneal times up to 20 minutes. Quantum efficiency measurements revealed that the post-annealed cells have more efficient electron collection, particularly below the CdS band edge, and a correlation is drawn between PLD annealing time and CdCl2 annealing time to optimize device efficiency. The results suggest that the in situ post PLD annealing process developed in this work is advantageous because of much improved crystallinity of CdS and CdTe, a considerably lower deposition thermal budget for better control of the CdS and CdTe interface, plus flexibility for in situ materials mixing for energy band gap engineering.

How the Starting Precursor Influences the Properties of Polycrystalline CuInGaSe2 Thin Films Prepared by Sputtering and Selenization

Cu(In,Ga)Se2 (CIGS)/CdS thin-film solar cells have reached, at laboratory scale, an efficiency higher than 22.3%, which is one of the highest efficiencies ever obtained for thin-film solar cells. The research focus has now shifted onto fabrication processes, which have to be easily scalable at an industrial level. For this reason, a process is highlighted here which uses only the sputtering technique for both the absorber preparation and the deposition of all the other materials that make up the cell. Particular emphasis is placed on the comparison between different precursors obtained with either In2Se3 and Ga2Se3 or InSe and GaSe as starting materials. In both cases, the precursor does not require any heat treatment, and it is immediately ready to be selenized. The selenization is performed in a pure-selenium atmosphere and only lasts a few minutes at a temperature of about 803 K. Energy conversion efficiencies in the range of 15%–16% are reproducibly obtained on soda-lime glass (SLG) substrates. Similar results are achieved if commercial ceramic tiles are used as a substrate instead of glass. This result is especially useful for the so-called building integrated photovoltaic. Cu(In,Ga)Se2-based solar cells grown directly on ceramic tiles are ideal for the fabrication of ventilated façades in low impact buildings.

Fabrication and Characterization of CdS Thin Film Synthesized by CBD Deposited from pH-Controlled Growth Solutions for Solar Cells Applications

This paper presents the fabrication and characterization of CdS thin film solar cells synthesized by chemical bath deposition using acid as a complexing agent with pH values between 10.1 and 11.3. We studied the influence of pH control of the reaction solution on the structural and optical properties of chemically deposited CdS thin films. Different films thicknesses of CdS were deposited onto a glass substrate. The structural surface morphology of as-deposited CdS thin films was characterized by scanning electron microscope, x-ray diffraction, profilometer, and ultraviolet–visible spectroscopy. The investigation of the effect of the synthesis method on the change the ammonium hydroxide by buffer pH 11 contributed in increases the growth kinetics, resulting thicker films. The films show high absorption and band gap values were found from 2.38 to 2.58 eV with different time deposition. The results are quite appreciable and high efficiency can be obtained from these CdS thin-film solar cells.

Modified equivalent circuits for $$\hbox {CuGaSe}_{2}$$ CuGaSe 2 thin films including space charge limited current

Current separation method has been used to identify the contribution of diode elements in the equivalent circuits of the thin film solar cells. This method is applied to analyse the current–voltage characteristics of the CuGaSe\(_2\)/CdS thin film solar cells measured under two different temperatures and several low illumination levels. The results reveal that the conventional double or single diode models are not well fitted to the experimental data under low illumination levels. However, the introduction of the space charge limited current element into the conventional equivalent circuits improves the fitness of the diode theory and experimental data. The voltage dependency of the space charge limited current is different under each operation condition. However, this voltage-dependency is not linear as was also reported in different literatures. For each single and double diode models, and for each illumination and operation temperature, the voltage dependency \((\hbox {V}^{\mathrm{m}})\) varies as \({\text {m}}=0.5, 1, 1.5, 2\).

04/01473 Method of determining heat value of fuel slurry and method of controlling combustion apparatus using the same: Nakajima, E. et al. Jpn. Kokai Tokkyo Koho JP 2003 161 404 (Cl. F23C10/28), 6 Jun 2003, Appl. 2001/360 126. (In Japanese)

In the processing of front-wall CdS thin film solar cells the films are given a strong HCl etch prior to formation of the Cu2S layer. This results in substantially higher cell outputs. Preliminary data are reported of a study of how HCl attacks CdS films and how the attack is affected by changes in the etching parameters, particularly time, temperature and acid concentration. Etched CdS films and replicas of etched CdS film surfaces were examined by scanning electron microscopy (SEM) and selected SEM photographs are presented to illustrate the effects. It is shown that etching textures the front surface of the CdS films and forms deep pits into the films. Pitting is the factor which varies most widely on differently processed films and which seems to correlate with the output level achievable from cells made from such films. the underlying substrate seems to be the factor having most influence on the etch pits.

The wet-topotaxial process of junction formation and surface treatments of Cu 2S–CdS thin-film solar cells

The particular properties of Cu 2S–CdS heterojunctions are revealed. The effects of lattice mismatch on epitaxy as well as wet- and dry-topotaxy are discussed and preconditions for successful application of topotaxy are elaborated. The influence of surface treatments of the cells and of additional semiconducting or metallic layers of monolayer-range thicknesses at the surface is demonstrated. The junction formation technology and the surface treatments appear to be relevant also to other photovoltaic devices.

Formation and Characterization of Electroless-Deposited NiTe2 Back Contacts to CdTe /CdS Thin-Film Solar Cells

The preparation and characterization of back contacts to CdTe/CdS cells are described. is formed on p-CdTe by electroless deposition at low reductant concentrations, producing devices that are superior (conversion efficiencies often exceeding 10%) to those contacted with electroless Ni. X-ray photoelectron spectroscopy and X-ray diffraction showed the product to be nickel(II) ditelluride produced, in the catalytic presence of ions, by the reaction of ions with a Te-rich CdTe surface, which is formed by an in situ etch in the chemical bath. Preliminary results indicate that Ni, from is not mobile within the cell structure, which is expected to be favorable for stability. Cells exhibit degradation when exposed to vapor. However, this effect was found to be reversible, with performance improving to near predegradation values following cell transfer to dry air conditions. © 2002 The Electrochemical Society. All rights reserved.

Characterization of [formula omitted] thin-film solar cells prepared using CBD

CuInSe 2 CdS thin-film heterojunction solar cells were fabricated entirely by chemical bath deposition technique. The illuminated J− V characteristics of the devices prepared with different thicknesses of CdS and CuInSe 2 were studied. The typical solar cell parameters obtained for the best cell are: V oc = 365 mV, J sc = 12 mA/cm 2, FF = 61%, and η = 3.1% under an illumination of 85 mW/cm 2 on a cell of active area 0.1 cm 2. The J− V and C− V characteristics under dark condition and the spectral response were also studied for the best cell. The diode quality factor obtained is 1.7.

Development of Cu 2SCdS thin film solar cells and transfer to industrial production

Development of Cu 2SCdS thin film solar cells and transfer to industrial production

CuxS/CdyZn1-yS and CuxS/CdyZn1-yS, CdS thin film solar cells using chemically sprayed films

Studies the effects of adding Zn to CdS films and solar cells. It was observed that the film surface structures were quite similar to CdS films although the electronic properties showed a marked difference as the film resistivity increased considerably with increasing Zn concentration. Measurements on uniformly doped CuxS/CdyZn1-yS solar cells showed no significant improvements in the photovoltaic response for concentrations up to 10% of Zn. Similar measurements on a CuxS/Cd0.9Zn0.1S, CdS solar cell, however, showed a significant increase in the open-circuit voltage, suggesting that the high series resistance in Zn-added films could be a cause for the observed low photovoltage.

Etching of CdS films

In the processing of front-wall CdS thin film solar cells the films are given a strong HCl etch prior to formation of the Cu 2S layer. This results in substantially higher cell outputs. Preliminary data are reported of a study of how HCl attacks CdS films and how the attack is affected by changes in the etching parameters, particularly time, temperature and acid concentration. Etched CdS films and replicas of etched CdS film surfaces were examined by scanning electron microscopy (SEM) and selected SEM photographs are presented to illustrate the effects. It is shown that etching textures the front surface of the CdS films and forms deep pits into the films. Pitting is the factor which varies most widely on differently processed films and which seems to correlate with the output level achievable from cells made from such films. the underlying substrate seems to be the factor having most influence on the etch pits.

A Comparative Study of Cu2S–ZnxCd1-xS and Cu2S–CdS Thin Film Solar Cells Prepared by Solid State Reaction

We report here all polycrystalline thin film solar cells of Cu2S–ZnxCd1-xS and Cu2S–CdS prepared by solid state reaction. The efficiencies in the range of 4 to 5% have been obtained without antireflection coating. The improvement in open circuit voltage is observed in Cu2S–ZnxCd1-xS cell with little sacrifice in short circuit current. A comparison is also made with the solar cell ZnxCd1-xS–Cu2S prepared by spray pyrolysis and the electrical conversion efficiency about 1.0% is obtained.

Status of Photovoltaic Power Technology

The status of photovoltaic power technology is reviewed primarily from the viewpoint of current and future applications of the technology to the exploration and utilization of space. The photovoltaic solar cell has been the electric power workhorse throughout the first decade of the space age. The technology has shown steady improvement in reliability, increased efficiency, reduced cost, increased power per unit of hardware weight and ability to withstand extremes of the space environment. New developments are underway to increase solar cell and array size, to reduce stowage volume during boosting into orbit and to improve resistance to space radiation and thermal cycling. Silicon cell electrical contacts and interconnections, low energy proton damage to small exposed cell areas and instability of CdS thin film solar cells are examples of problems receiving attention at this time. The ongoing development of large, 2500–3000 ft2, solar cell arrays to power the planned Apollo Applications Telescope/Workshop Cluster demonstrates the growing confidence in the ability of photovoltaic power to handle space missions of the future. As photovoltaic technology advances and economic conditions change, the solar cell may well find large scale terrestrial markets.

The history, design, fabrication and performance of CdS thin film solar cells

The history of the thin film CdS solar cell is traced from its first reduction to practice in 1955 to the present. The major factors which contributed to the evolution of the present 4–8% large area light weight cell are discussed. Various possible constructions of CdS thin film solar cells are described along with the advantages and disadvantages of each. A brief outline is given of the steps in fabricating the present design high efficiency cell, along with the more important process parameters. The operating characteristics of the best present state-of-the-art cells are presented in detail including the effect of light intensity and temperature on the voltage, current and power output, the spectral responses, and the factors affecting cell stability. There is a brief discussion of the possibilities for further improvements in these cells, and a listing of some of their probable applications in space and on earth.

The effects of electron and proton irradiation on thin film solar cells

Electron and proton radiation effects on GaAs, CdS and CdTe thin film solar cells noting proton damage, estimates on cell life, etc