Toxic Materials Used in Thin Film Photovoltaics and Their Impacts on Environment

Photovoltaic industry has proved to be a growing and advantageous source of energy as it can be renewable, sustainable, reliable and clean. Significant improvements have been made in materials used and the production processes to reduce the costs, and to avoid possible issues induced by some hazardous materials. However, some health and environment challenges last, which must be overcome to make this technology a source of truly clean energy. This chapter provides an overview on the major environmental impacts of thin film technology associated with the use of toxic materials and the chemicals in the manufacturing processes. A summary of Environmental, Health and Safety issues associated with some thin film technologies like copper indium gallium diselenide (CIS/CIGS), cadmium telluride (CdTe) and amorphous silicon (a-Si) is done, in order to investigate potential infections induced by the environmental release of trace elements, usually coming from chemical vapor inhalation and eventually accidental spills during the manufacturing processes, on the health of humans and animals. Potential solutions will be provided to prevent some environmental issues

Optoelectronic characterization of CuInGa(S)2 thin films grown by spray pyrolysis for photovoltaic application

[EN] Copper-indium gallium disulfide (CIGS) is a good absorber for photovoltaic application. Thin films of CIGS were prepared by spray pyrolysis on glass substrates in the ambient atmosphere. The films were characterized by different techniques, such as structural, morphological, optical and electrical properties of CIGS films were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), spectrophotometer and Hall effect, respectively. After optimization, the deposited films structure, grain size, and crystallinity became more important with an increase of annealing time at 370 degrees C for 20 min. Transmission electron microscopy (TEM) analysis shows that the interface sheets are well crystallized and the inter planer distance are 0.25 nm, 0.28 nm, and 0.36 nm. The atomic force microscopy (AFM) observation shows that the grain size and roughness can be tolerated by optimizing the annealing time. The strong absorbance and low transmittance were observed for the prepared films with a suitable energy bandgap about 1.46 eV. The Hall effect measurement system examined that CIGS films exhibited optimal electrical properties, resistivity, carrier mobility, and carrier concentration which were determined to be 4.22 x 10(6) omega cm, 6.18 x 10(2) cm(2) V-1 S-1 and 4.22 x 10(6) cm(-3), respectively. The optoelectronic properties of CIGS material recommended being used for the photovoltaic application.Prof. Bouchaib HARTITI, The Senior Associate at ICTP, is very grateful to ICTP for permanent support. Prof. Mohamed Ebn Touhami, Director of the University Center for Analysis, Expertise, Transfer of Technology and Incubation, Kenitra, Morocco, is very grateful to CUA2TI for financial support. Thanks to Doctor Diogo M.F. Santos for the supervision of Amal Bouich's work during her research in CeFEMA research center. The authors also thank researchers from CeFEMA (IST-ULisboa, Portugal) and CUA2TI (FS-Kenitra Morocco) for their help.Bouich, A.; Hartiti, B.; Ullah, S.; Ullah, H.; Ebn Touhami, M.; Santos, DMF.; Marí, B. (2019). Optoelectronic characterization of CuInGa(S)2 thin films grown by spray pyrolysis for photovoltaic application. Applied Physics A. 125(8):1-9. https://doi.org/10.1007/s00339-019-2874-4S191258T. Feurer, P. Reinhard, E. Avancini, B. Bissig, J. Löckinger, P. Fuchs, S. Buecheler, Progress in thin film CIGS photovoltaics–Research and development, manufacturing, and applications. Prog. Photovolt. Res. Appl. 25(7), 645–667 (2017)A. Zegadi, M.A. Slifkin, M. Djamin, A.E. Hill, R.D. Tomlinson, A photoacoustic study of CuInxGa1− xSe2 alloys. Phys. Status Solidi (A) 133(2), 533–540 (1992)T.H. Sajeesh, A.R. Warrier, C.S. Kartha, K.P. Vijayakumar, Optimization of parameters of chemical spray pyrolysis technique to get n and p-type layers of SnS. Thin Solid Films 518(15), 4370–4374 (2010)J. Liu, D. Zhuang, H. Luan, M. Cao, M. Xie, X. Li, Preparation of Cu (In, Ga) Se2 thin film by sputtering from Cu (In, Ga) Se2 quaternary target. Progr. Nat. Sci. Mater. Int. 23(2), 133–138 (2013)M.I. Hossain, Fabrication and characterization of CIGS solar cells with In2 S3 buffer layer deposited by PVD technique. Chalcogenide Lett. 9(5), 185–191 (2012)M.A. Mughal, R. Engelken, R. Sharma, Progress in indium (III) sulfide (In2S3) buffer layer deposition techniques for CIS, CIGS, and CdTe-based thin film solar cells. Sol. Energy 120, 131–146 (2015)M. Powalla, M. Cemernjak, J. Eberhardt, F. Kessler, R. Kniese, H.D. Mohring, B. Dimmler, Large-area CIGS modules: Pilot line production and new developments. Sol. Energy Mater Sol. Cells 90(18–19), 3158–3164 (2006)M.E. Calixto, P.J. Sebastian, R.N. Bhattacharya, R. Noufi, Compositional and optoelectronic properties of CIS and CIGS thin films formed by electrodeposition. Sol. Energy Mater. Sol. Cells 59(1–2), 75–84 (1999)S. Jung, S. Ahn, J.H. Yun, J. Gwak, D. Kim, K. Yoon, Effects of Ga contents on properties of CIGS thin films and solar cells fabricated by co-evaporation technique. Curr. Appl. Phys. 10(4), 990–996 (2010)S. R. Ovshinsky, X. Deng, R. Young, U.S. Patent No. 5,231,047. Washington, DC: U.S. Patent and Trademark Office (1993).M. Kaelin, D. Rudmann, A.N. Tiwari, Low cost processing of CIGS thin film solar cells. Sol. Energy 77(6), 749–756 (2004)Fangdan Jiang, Jiayou Feng, Effect of temperature on selenization process of metallic Cu–In alloy precursors. Thin Solid Films 515(4), 1950–1955 (2006)S. Shirakata, Y. Kannaka, H. Hasegawa, T. Kariya, S. Isomura, Properties of Cu (In, Ga) Se2 thin films prepared by chemical spray pyrolysis. Jpn. J. Appl. Phys. 38(9R), 4997 (1999)Y.K. Kumar, G.S. Babu, P.U. Bhaskar, V.S. Raja, Effect of starting-solution pH on the growth of Cu2ZnSnS4 thin films deposited by spray pyrolysis. Phys. Status Solidi (A) 206(7), 1525–1530 (2009)M. Ajili, M. Castagné, N.K. Turki, Characteristics of CuIn1− xGaxS2 thin films synthesized by chemical spray pyrolysis. J. Lumin. 150, 1–7 (2014)B.J. Babu, S. Velumani, A. Kassiba, R. Asomoza, J.A. Chavez-Carvayar, J. Yi, Deposition and characterization of graded Cu (In1-xGax) Se2 thin films by spray pyrolysis. Mater. Chem. Phys. 162, 59–68 (2015)S.F. Varol, G. Babür, G. Çankaya, U. Kölemen, Synthesis of sol–gel derived nano-crystalline ZnO thin films as TCO window layer: effect of sol aging and boron. RSC Adv. 4(100), 56645–56653 (2014)J.A. Frantz, R.Y. Bekele, V.Q. Nguyen, J.S. Sanghera, A. Bruce, S.V. Frolov, I.D. Aggarwal, Cu (In, Ga) Se2 thin films and devices sputtered from a single target without additional selenization. Thin Solid Films 519(22), 7763–7765 (2011)C. Calderón, G. Gordillo, P. Bartolo-Pérez, F. Mesa, Effect of the deposition conditions on the optical, morphological and compositional properties of CuIn1− xGaxSe2 thin films prepared by a multistage process. 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Optik 183, 137–147 (2019

The optical parameters of CuInS2 thin films deposited by spray pyrolysis method for photovoltaic applications

International audienceIn this work, CuInS2 (CIS) thin films were prepared by spray pyrolysis method, and optical properties were investigated. CuInS2 in the form of films is prepared at different deposition conditions by a simple and economical spray pyrolysis method. Optical constants such as band gap Eg, extinction coefficient k, refractive index n, and dielectric constants e1 and e2 were determined from the measured transmittance and absorption spectra in the wavelength range between 550-850 nm. Furthermore, the optical band gap values were calculated by the Tauc model. The absorption spectra of the films showed that this compound is a direct band gap material. The major result of this study is optical properties of CuInS2. © 2015 IEEE

Characteristics of CuInS2 thin films synthesizes by chemical spray pyrolysis

International audienceCuInS2 multi-component semiconductors thin films were prepared by chemical spray pyrolysis at different deposition conditions. The structural, optical, and electrical properties of the films were investigated. Samples were characterized using Raman spectroscopy, spectrophotometric and the 4-point probe method. Raman spectra indicate that the sprayed thin films are grown only with CH-ordering. Optical analysis by means of transmittance T(λ) and absorption A(λ) measurements in the wavelength range between 550 and 850 nm allow us to determine the direct band gap energy. Resistivity studies of the samples revealed that HK-S1 was less resistive than the other samples

Determination of the optimal conditions for the deposition of Cadmium sulfide thin films by chemical bath deposition using Taguchi method

International audienceThin films of Cadmium sulfide (CdS) is one of the promising semiconductor materials which can be used as a tampon materials deposited by chemical bath deposition (CBD) in thin film solar cells thanks to its tunable direct band gap energy, large transmission coefficient and cost effective. The role of the CdS layer is still debated within the scientific community, but the material efficiency obtained with this fine n-type semiconductor layer is very high. It could protect the damage associated with the following spray deposits of defects in the surface of the absorber or adapt the width of the energy band gap between the absorber (∼1.2 (eV)) and the window layer (∼3.3 (eV)). The aim of this present study is to investigate the influence of deposition parameters of CdS thin films using the L9 orthogonal array of the Taguchi's design of experiments (DOE) elaborated by CBD method on ordinary glass substrate. The Taguchi design was used to evaluate the effects of four deposition parameters called factors namely the ratios [Cd]/[S], time of deposition, Ammonia concentration [NH4Cl] and volume ratio V(H2O)/V(NH3) on optical properties of elaborated films. The identification of the most influent factor of the deposition process on the band gap energy of elaborated films is also done by employing the analysis of variance (ANOVA). The Taguchi analysis employed in the present investigation led to optimize process parameters for the most optimal deposition conditions. Under the optimized configuration, the CdS films showed optimal gap energy of 2.42 (eV) [1]. The Taguchi analysis employed in the present investigation led to optimize process parameters for the most optimal deposition conditions. © 2015 IEEE

Effect of different S/In ratio of In2S3 films prepared by chemical spray pyrolysis method

International audienceIn2S3 thin films were prepared using chemical spray pyrolysis technique. An aqueous solution of InCl3 and CS(NH2)2 was sprayed on to glass substrates and kept at 300 °C, using air as a carrier gas. Stoichiometry of the films was varied by adjusting the molarity of the spray solution. Structure and properties of films with different S/In ratios have been investigated. Raman spectroscopy present bands at 302 and 329 cm-1 indicating the presence of the β-phase in all the films. Optical transmittance of films is over 80% in the visible region and its energy band gap decreases from 2.7 to 2.67 ev. PL emission in the wavelength range 300-800 nm was recorded

Influence of silver doped indium sulfide on the structural and optical properties of spray pyrolyzed indium sulfide thin films

International audienceSilver doped indium sulfide thin films were deposited on ordinary glass substrates at 350°C, using chemical spray pyrolysis (CSP) technique. The samples have been prepared by varying the Ag/In ratio in solution from 0 % to 4 %. The effect of silver on structural and optical properties of In2S3Ag thin films has been investigated in detail using various characterization tools. XRD patterns confirmed that all the films have a nanocrystalline nature. The Raman spectroscopy showed the main mode at 306 cm-1 and 327 cm-1 indicating the presence of the β-phase in all films. Optical transmittance of spray pyrolyzed films exceeds 80% in the visible region and band gaps are estimated varying from 2.60 eV to 2.73 eV. © 2016 IEEE

Synthesis and characterization of CuO thin films grown by chemical spray pyrolysis

International audienceIn this study, nanostructured cupric oxide (CuO) thin films were deposited using simple spray pyrolysis technique on glass substrates with a fixed temperature at 375 ∘C. The films were deposited at different precursor molarities 0.035, 0.05 and 0.1 M using (CuCl2· 2 H2O) as precursor. The characterizations used such as X-ray diffraction (XRD) shows the formation of pure polycrystalline CuO with tenorite phase which belongs to a monoclinic structure. Raman spectroscopy confirms what we obtained in XRD. The films deposited with 0.1 M show high absorbance. The gap energy decreased from 1.58 to 1.53 eV with increasing precursor concentration from 0.035 to 0.1 M. Other optical parameters such as refractive index, extinction coefficient and dielectric constants were calculated through absorbance/transmittance data extracted from spectrophotometry. © 2017, Springer Science+Business Media New York