Submit to Coatings Review for Coatings Propose a Special Issue

Journal Browser

► Journal Browser

Novel Thin Film Materials for Photovoltaic Applications

Special Issue Editors
Special Issue Information
Keywords
Published Papers

A special issue of Coatings (ISSN 2079-6412).

Deadline for manuscript submissions: closed (31 August 2015) | Viewed by 138822

Share This Special Issue

Special Issue Editors

Prof. Dr. Francesco Di Benedetto

E-Mail Website
Guest Editor

Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via La Pira 4, 50121 Firenze, Italy

Prof. Dr. Susan Schorr

E-Mail Website
Guest Editor

Crystallography, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, Berlin, Germany

Special Issue Information

Dear Colleagues,

The energy predicament, due to the impending Hubbert’s Peak Oil theory combined with the environmental consequences of CO₂ emissions, dictate the need for a rapid transition from fossil fuels to renewable and sustainable energy sources to power the social and economic global metabolism. The last few years have witnessed an exponential growth of renewable power produced in major developed countries, mostly from wind farms and photovoltaic (PV) plants.
The growing demand of energy represents the main driving force of research in the field of new PV materials and new technological solutions, in order to confront two apparent problems: the rarefaction of the mineral resources and the need of developing an environmentally friendly and sustainable energy supply system.
The aim of this Special Issue consists of attracting worldwide researchers in participating to create a state-of-the-art summary of the recent increase in scientific and technological knowledge on new materials for thin film technology. This could include specific references to the synthetic routes for absorber powders and crystals, to the strategies for the realization of thin film devices, the characterization of the mineralogical, crystal chemical, structural, thermodynamic and physical properties of substrates and devices, and perspectives for the subject.
In this respect, special emphasis will be given to new data on consolidated materials for thin film technology, such as for example, cadmium telluride (CdTe), copper indium gallium sulfides and selenides, Cu(In,Ga)S₂/Se₂ (CIGS, CIGSe), new promising materials such as kesterites,Cu₂ZnSnS₄ or Cu₂ZnSnSe₄ (CZTS, CZTSe), as well as other emerging materials for thin film solar cell applications.

Prof. Dr. Francesco Di Benedetto
Prof. Dr. Susan Schorr
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

photovoltaic materials
thin film technology
CdTe
chalcopyrites
CIGS
kesterites
CZTS
new materials
materials and thin film characterization

Published Papers (11 papers)

Download All Papers

Research

Jump to: Review

768 KiB

Open AccessArticle

Fabrication and Characterization of a Perovskite-Type Solar Cell with a Substrate Size of 70 mm

by Takeo Oku, Taisuke Matsumoto, Atsushi Suzuki and Kohei Suzuki

Coatings 2015, 5(4), 646-655; https://doi.org/10.3390/coatings5040646 - 13 Oct 2015

Cited by 24 | Viewed by 10315

Abstract

A perovskite-type solar cell with a substrate size of 70 mm × 70 mm was fabricated by a simple spin-coating method using a mixed solution. The photovoltaic properties of the TiO₂/CH₃NH₃PbI₃-based photovoltaic devices were investigated by current density-voltage characteristic and incident photon to current conversion efficiency measurements. Their short-circuit current densities were almost constant over a large area. The photoconversion efficiency was influenced by the open-circuit voltage, which depended on the distance from the center of the cell. Full article

(This article belongs to the Special Issue Novel Thin Film Materials for Photovoltaic Applications)

► Show Figures

Figure 1

990 KiB

Open AccessArticle

Electrical and Optical Properties of Fluorine Doped Tin Oxide Thin Films Prepared by Magnetron Sputtering

by Ziad Y. Banyamin, Peter J. Kelly, Glen West and Jeffery Boardman

Coatings 2014, 4(4), 732-746; https://doi.org/10.3390/coatings4040732 - 30 Oct 2014

Cited by 203 | Viewed by 17424

Abstract

Fluorine doped tin oxide (FTO) coatings have been prepared using the mid-frequency pulsed DC closed field unbalanced magnetron sputtering technique in an Ar/O₂ atmosphere using blends of tin oxide and tin fluoride powder formed into targets. FTO coatings were deposited with a thickness of 400 nm on glass substrates. No post-deposition annealing treatments were carried out. The effects of the chemical composition on the structural (phase, grain size), optical (transmission, optical band-gap) and electrical (resistivity, charge carrier, mobility) properties of the thin films were investigated. Depositing FTO by magnetron sputtering is an environmentally friendly technique and the use of loosely packed blended powder targets gives an efficient means of screening candidate compositions, which also provides a low cost operation. The best film characteristics were achieved using a mass ratio of 12% SnF₂ to 88% SnO₂in the target. The thin film produced was polycrystalline with a tetragonal crystal structure. The optimized conditions resulted in a thin film with average visible transmittance of 83% and optical band-gap of 3.80 eV, resistivity of 6.71 × 10⁻³ Ω·cm, a carrier concentration (N_d) of 1.46 × 10²⁰ cm⁻³ and a mobility of 15 cm²/Vs. Full article

(This article belongs to the Special Issue Novel Thin Film Materials for Photovoltaic Applications)

► Show Figures

Figure 1

3397 KiB

Open AccessArticle

Fabrication of CdS/CdTe-Based Thin Film Solar Cells Using an Electrochemical Technique

by I. M. Dharmadasa, P. A. Bingham, O. K. Echendu, H. I. Salim, T. Druffel, R. Dharmadasa, G. U. Sumanasekera, R. R. Dharmasena, M. B. Dergacheva, K. A. Mit, K. A. Urazov, L. Bowen, M. Walls and A. Abbas

Coatings 2014, 4(3), 380-415; https://doi.org/10.3390/coatings4030380 - 27 Jun 2014

Cited by 95 | Viewed by 14691

Abstract

Thin film solar cells based on cadmium telluride (CdTe) are complex devices which have great potential for achieving high conversion efficiencies. Lack of understanding in materials issues and device physics slows down the rapid progress of these devices. This paper combines relevant results from the literature with new results from a research programme based on electro-plated CdS and CdTe. A wide range of analytical techniques was used to investigate the materials and device structures. It has been experimentally found that n-, i- and p-type CdTe can be grown easily by electroplating. These material layers consist of nano- and micro-rod type or columnar type grains, growing normal to the substrate. Stoichiometric materials exhibit the highest crystallinity and resistivity, and layers grown closer to these conditions show n → p or p → n conversion upon heat treatment. The general trend of CdCl₂ treatment is to gradually change the CdTe material’s n-type electrical property towards i-type or p-type conduction. This work also identifies a rapid structural transition of CdTe layer at 385 ± 5 °C and a slow structural transition at higher temperatures when annealed or grown at high temperature. The second transition occurs after 430 °C and requires more work to understand this gradual transition. This work also identifies the existence of two different solar cell configurations for CdS/CdTe which creates a complex situation. Finally, the paper presents the way forward with next generation CdTe-based solar cells utilising low-cost materials in their columnar nature in graded bandgap structures. These devices could absorb UV, visible and IR radiation from the solar spectrum and combine impact ionisation and impurity photovoltaic (PV) effect as well as making use of IR photons from the surroundings when fully optimised. Full article

(This article belongs to the Special Issue Novel Thin Film Materials for Photovoltaic Applications)

► Show Figures

Figure 1

760 KiB

Open AccessArticle

Microstructures and Photovoltaic Properties of Zn(Al)O/Cu₂O-Based Solar Cells Prepared by Spin-Coating and Electrodeposition

by Takeo Oku, Tetsuya Yamada, Kazuya Fujimoto and Tsuyoshi Akiyama

Coatings 2014, 4(2), 203-213; https://doi.org/10.3390/coatings4020203 - 31 Mar 2014

Cited by 39 | Viewed by 10984

Abstract

Copper oxide (Cu₂O)-based heterojunction solar cells were fabricated by spin-coating and electrodeposition methods, and photovoltaic properties and microstructures were investigated. Zinc oxide (ZnO) and Cu₂O were used as n- and p-type semiconductors, respectively, to fabricate photovoltaic devices based on In-doped tin oxide/ZnO/Cu₂O/Au heterojunction structures. Short-circuit current and fill factor increased by aluminum (Al) doping in the ZnO layer, which resulted in the increase of the conversion efficiency. The efficiency was improved further by growing ZnO and Cu₂O layers with larger crystallite sizes, and by optimizing the Al-doping by spin coating. Full article

(This article belongs to the Special Issue Novel Thin Film Materials for Photovoltaic Applications)

► Show Figures

Figure 1

820 KiB

Open AccessArticle

Spray-on PEDOT:PSS and P3HT:PCBM Thin Films for Polymer Solar Cells

by Morteza Eslamian and Joshua E. Newton

Coatings 2014, 4(1), 85-97; https://doi.org/10.3390/coatings4010085 - 21 Jan 2014

Cited by 19 | Viewed by 12414

Abstract

PEDOT:PSS electron-blocking layer, and PEDOT:PSS + P3HT:PCBM stacked layers are fabricated by ultrasonic atomization and characterized by scanning electron microscopy (SEM) and optical profilometry. The measured thicknesses based on SEM and optical profilometry are quite different, indicating the incapability of measurement techniques for non-uniform thin films. The thickness measurements are compared against theoretical estimations and a qualitative agreement is observed. Results indicate that using a multiple pass fabrication strategy results in a more uniform thin film. It was also found that the film characteristics are a strong function of solution concentration and spraying passes, and a weak function of substrate speed. Film thickness increases with solution concentration but despite the prediction of theory, the increase is not linear, indicating a change in the film porosity and density, which can affect physical and opto-electrical properties. Overall, while spray coating is a viable fabrication process for a wide range of solar cells, film characteristics can be easily altered by a change in process parameters. Full article

(This article belongs to the Special Issue Novel Thin Film Materials for Photovoltaic Applications)

► Show Figures

Figure 1

1692 KiB

Open AccessArticle

An Investigation into W or Nb or ZnFe₂O₄ Doped Titania Nanocomposites Deposited from Blended Powder Targets for UV/Visible Photocatalysis

by Nick Farahani, Peter J. Kelly, Glen West, Marina Ratova, Claire Hill and Vladimir Vishnyakov

Coatings 2013, 3(3), 153-165; https://doi.org/10.3390/coatings3030153 - 14 Aug 2013

Cited by 3 | Viewed by 5881

Abstract

The photocatalytic behavior of titania coatings is largely determined by their crystalline structure. Depending on deposition conditions, though, titania may form amorphous, brookite, anatase or rutile structures, with anatase or anatase/rutile mixed phase structures showing the highest levels of activity. Anatase is activated by UV light and, consequently, there is a great deal of interest in doping titania films to both increase activity and extend it into the visible range. In this study, titania and doped titania coatings have been deposited from blended oxide powder targets. This highly versatile and economical technique allows dopant levels to be readily varied. Using this technique, titania coatings doped with W, Nb and ZnFe2O4 have been deposited onto glass substrates by pulsed magnetron sputtering. The as-deposited coatings were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and micro-Raman spectroscopy. Selected coatings were then annealed at temperatures in the range of 400–700 °C and re-analyzed. Structural transformation of the titania coatings was initiated in the 500–600 °C range, with the coatings annealed at 700 °C having predominantly anatase structures. The photocatalytic activity of the coatings was assessed through measurements of the degradation of organic dyes, such as methyl orange, under the influence of UV and fluorescent light sources. It was found that, after annealing, coatings with photo-active surfaces were produced and that activity varied with dopant content. Activity levels under fluorescent light irradiation were up to 60% of the activity measured under UV irradiation. Full article

(This article belongs to the Special Issue Novel Thin Film Materials for Photovoltaic Applications)

► Show Figures

Figure 1

Review

Jump to: Research

17447 KiB

Open AccessReview

Review on the Photocatalyst Coatings of TiO₂: Fabrication by Mechanical Coating Technique and Its Application

by Yun Lu, Sujun Guan, Liang Hao and Hiroyuki Yoshida

Coatings 2015, 5(3), 425-464; https://doi.org/10.3390/coatings5030425 - 30 Jul 2015

Cited by 21 | Viewed by 10353

Abstract

This review presents the latest results of studies directed at photocatalyst coatings of titanium dioxide (TiO₂) prepared by mechanical coating technique (MCT) and its application. Compared with traditional coating techniques, MCT is a simple, low cost and useful coating formation process, which is proposed and developed based on mechanical frictional wear and impacts between substrate materials and metal powder particles in the bowl of planetary ball mill. The formation process of the metal coatings in MCT includes four stages: The nucleation by adhesion, the formation and coalescence of discrete islands, formation and thickening of continuous coatings, exfoliation of continuous coatings. Further, two-step MCT was developed based on the MCT concept for preparing composite coatings on alumina (Al₂O₃) balls. This review also discusses the influence on the fabrication of photocatalyst coatings after MCT and improvement of its photocatalytic activity: oxidation conditions, coating materials, melt salt treatment. In this review, the oxidation conditions had been studied on the oxidation temperature of 573 K, 673 K, 773 K, 873 K, 973 K, 1173 K and 1273 K, the oxidation time of 0.5 h, 1 h, 3 h, 10 h, 15 h, 20 h, 30 h, 40 h, and 50 h. The photocatalyst coatings showed the highest photocatalytic activity with the oxidation condition of 1073 K for 15 h. The metal powder of Ti, Ni and Cr had been used as the coating materials. The composite metal powder could affect the surface structure and photocatalytic activity. On the other hand, the melt salt treatment with KNO₃ is an effective method to form the nano-size structure and enhance photocatalytic activity, especially under visible light. Full article

(This article belongs to the Special Issue Novel Thin Film Materials for Photovoltaic Applications)

► Show Figures

Figure 1

940 KiB

Open AccessReview

Chalcopyrite Thin Film Materials for Photoelectrochemical Hydrogen Evolution from Water under Sunlight

by Hiroyuki Kaneko, Tsutomu Minegishi and Kazunari Domen

Coatings 2015, 5(3), 293-311; https://doi.org/10.3390/coatings5030293 - 17 Jul 2015

Cited by 20 | Viewed by 8011

Abstract

Copper chalcopyrite is a promising candidate for a photocathode material for photoelectrochemical (PEC) water splitting because of its high half-cell solar-to-hydrogen conversion efficiency (HC-STH), relatively simple and low-cost preparation process, and chemical stability. This paper reviews recent advances in copper chalcopyrite photocathodes. The PEC properties of copper chalcopyrite photocathodes have improved fairly rapidly: HC-STH values of 0.25% and 8.5% in 2012 and 2015, respectively. On the other hand, the onset potential remains insufficient, owing to the shallow valence band maximum mainly consisting of Cu 3d orbitals. In order to improve the onset potential, we explored substituting Cu for Ag and investigate the PEC properties of silver gallium selenide (AGSe) thin film photocathodes for varying compositions, film growth atmospheres, and surfaces. The modified AGSe photocathodes showed a higher onset potential than copper chalcopyrite photocathodes. It was demonstrated that element substitution of copper chalcopyrite can help to achieve more efficient PEC water splitting. Full article

(This article belongs to the Special Issue Novel Thin Film Materials for Photovoltaic Applications)

► Show Figures

Figure 1

1142 KiB

Open AccessReview

Review of the CdCl₂ Treatment Used in CdS/CdTe Thin Film Solar Cell Development and New Evidence towards Improved Understanding

by I. M. Dharmadasa

Coatings 2014, 4(2), 282-307; https://doi.org/10.3390/coatings4020282 - 30 Apr 2014

Cited by 124 | Viewed by 14071

Abstract

Cadmium chloride treatment is a key processing step identified in the late 1970s to drastically improve the solar to electric conversion efficiency of CdS/CdTe thin film solar cells. Although a large body of experimental results are available to date, this process is yet to be understood even after three decades of research. This paper reviews the experimental results available, presents some new clues leading to improved understanding and suggests key research areas necessary to fully understand this crucial processing step. Improved understanding will lead to further increase in conversion efficiency of CdS/CdTe solar cells well beyond 20%. Full article

(This article belongs to the Special Issue Novel Thin Film Materials for Photovoltaic Applications)

► Show Figures

Figure 1

919 KiB

Open AccessReview

Applications of Oxide Coatings in Photovoltaic Devices

by Sonya Calnan

Coatings 2014, 4(1), 162-202; https://doi.org/10.3390/coatings4010162 - 24 Mar 2014

Cited by 43 | Viewed by 14145

Abstract

Metalloid and metal based oxides are an almost unavoidable component in the majority of solar cell technologies used at the time of writing this review. Numerous studies have shown increases of ≥1% absolute in solar cell efficiency by simply substituting a given layer in the material stack with an oxide. Depending on the stoichiometry and whether other elements are present, oxides can be used for the purpose of light management, passivation of electrical defects, photo-carrier generation, charge separation, and charge transport in a solar cell. In this review, the most commonly used oxides whose benefits for solar cells have been proven both in a laboratory and industrial environment are discussed. Additionally, developing trends in the use of oxides, as well as newer oxide materials, and deposition technologies for solar cells are reported. Full article

(This article belongs to the Special Issue Novel Thin Film Materials for Photovoltaic Applications)

► Show Figures

Figure 1

656 KiB

Open AccessReview

Spray-on Thin Film PV Solar Cells: Advances, Potentials and Challenges

by Morteza Eslamian

Coatings 2014, 4(1), 60-84; https://doi.org/10.3390/coatings4010060 - 21 Jan 2014

Cited by 133 | Viewed by 19479

Abstract

The capability to fabricate photovoltaic (PV) solar cells on a large scale and at a competitive price is a milestone waiting to be achieved. Currently, such a fabrication method is lacking because the effective methods are either difficult to scale up or expensive due to the necessity for fabrication in a vacuum environment. Nevertheless, for a class of thin film solar cells, in which the solar cell materials can be processed in a solution, up scalable and vacuum-free fabrication techniques can be envisioned. In this context, all or some layers of polymer, dye-sensitized, quantum dot, and copper indium gallium selenide thin film solar cells illustrate some examples that may be processed in solution. The solution-processed materials may be transferred to the substrate by atomizing the solution and carrying the spray droplets to the substrate, a process that will form a thin film after evaporation of the solvent. Spray coating is performed at atmospheric pressure using low cost equipment with a roll-to-roll process capability, making it an attractive fabrication technique, provided that fairly uniform layers with high charge carrier separation and transport capability can be made. In this paper, the feasibility, the recent advances and challenges of fabricating spray-on thin film solar cells, the dynamics of spray and droplet impaction on the substrate, the photo-induced electron transfer in spray-on solar cells, the challenges on characterization and simulation, and the commercialization status of spray-on solar cells are discussed. Full article

(This article belongs to the Special Issue Novel Thin Film Materials for Photovoltaic Applications)

► Show Figures