http://www.mdpi.com/journal/materials/special_issues/solar_energy/ Dear Colleagues, Solar energy materials are used to harness the sun’s energy to the benefit of mankind. Their optical properties are tuned to the radiation that prevails in our ambience and they can absorb, reflect, transmit or emit radiation in the wavelength ranges for thermal, solar and visible radiation. Among their applications we note solar cells of many types, solar thermal collectors, energy efficient windows and facades with static or dynamic properties, photo-catalytic converters, self-cleaning surfaces, surfaces for passive radiative cooling, to and many more. The materials can be metals, semiconductors and dielectrics including polymers; they can bulk-like as well as thin films. Nanomaterials are of particular interest. Fundamental and applied work, including thin film deposition, is of interest for this journal issue. Guest Editor Prof. Dr. Claes-Göran S. Granqvist {snippet name="submission_info"} http://www.mdpi.com/1996-1944/3/12/5143/ The aim of this review is to present the actual status of development in adaptive solar control by use of thermotropic and organic thermochromic materials. Such materials are suitable for application in smart windows. In detail polymer blends, hydrogels, resins, and thermoplastic films with a reversible temperature-dependent switching behavior are described. A comparative evaluation of the concepts for these energy efficient materials is given as well. Furthermore, the change of strategy from ordinary shadow systems to intrinsic solar energy reflection materials based on phase transition components and a first remark about their realization is reported. Own current results concerning extruded films and high thermally stable casting resins with thermotropic properties make a significant contribution to this field. http://www.mdpi.com/1996-1944/3/12/5143/ Mon, 06 Dec 2010 00:00:00 CET Materials 2010-12-06 3 12 Review 5143 5168 1996-1944 Thermotropic and Thermochromic Polymer Based Materials for Adaptive Solar Control 2010-12-06 doi: 10.3390/ma3125143 Arno Seeboth Ralf Ruhmann Olaf Mühling http://www.mdpi.com/1996-1944/3/12/5029/ The recent progress in application of nanostructures in electrochromic materials and devices is reviewed. ZnO nanowire array modified by viologen and WO3, crystalline WO3 nanoparticles and nanorods, mesoporous WO3 and TiO2, poly(3,4-ethylenedioxythiophene) nanotubes, Prussian blue nanoinks and nanostructures in switchable mirrors are reviewed. The electrochromic properties were significantly enhanced by applying nanostructures, resulting in faster switching responses, higher stability and higher optical contrast. A perspective on the development trends in electrochromic materials and devices is also proposed. http://www.mdpi.com/1996-1944/3/12/5029/ Fri, 26 Nov 2010 00:00:00 CET Materials 2010-11-26 3 12 Review 5029 5053 1996-1944 Application of Nanostructures in Electrochromic Materials and Devices: Recent Progress 2010-11-26 doi: 10.3390/ma3125029 Jin Min Wang Xiao Wei Sun Zhihui Jiao http://www.mdpi.com/1996-1944/3/11/4939/ The solvent vapor treatment (SVT) for poly(3-hexylthiophene) (PAT6) films and its application to interpenetrating heterojunction organic solar cells have been studied. It was found that SVT could improve the crystallinity and electrical characteristics of the PAT6 films. We fabricated organic solar cells with an interpenetrating structure of PAT6 and fullerenes utilizing the SVT process, and discuss the improved performance of the solar cells by taking the film crystallinity, optical properties, and morphology into consideration. http://www.mdpi.com/1996-1944/3/11/4939/ Mon, 15 Nov 2010 00:00:00 CET Materials 2010-11-15 3 11 Article 4939 4949 1996-1944 Solvent Vapor Treatment Effects on Poly(3-hexylthiophene) Thin Films and its Application for Interpenetrating Heterojunction Organic Solar Cells 2010-11-15 doi: 10.3390/ma3114939 Tetsuro Hori Varutt Kittichungchit Hiroki Moritou Hitoshi Kubo Akihiko Fujii Masanori Ozaki http://www.mdpi.com/1996-1944/3/11/4922/ This article provides a comprehensive overview of the work to date on the two‑step solar H2O and/or CO2 splitting thermochemical cycles with Zn/ZnO redox reactions to produce H2 and/or CO, i.e., synthesis gas—the precursor to renewable liquid hydrocarbon fuels. The two-step cycle encompasses: (1) The endothermic dissociation of ZnO to Zn and O2 using concentrated solar energy as the source for high-temperature process heat; and (2) the non-solar exothermic oxidation of Zn with H2O/CO2 to generate H2/CO, respectively; the resulting ZnO is then recycled to the first step. An outline of the underlying science and the technological advances in solar reactor engineering is provided along with life cycle and economic analyses. http://www.mdpi.com/1996-1944/3/11/4922/ Fri, 12 Nov 2010 00:00:00 CET Materials 2010-11-12 3 11 Review 4922 4938 1996-1944 Review of the Two-Step H2O/CO2-Splitting Solar Thermochemical Cycle Based on Zn/ZnO Redox Reactions 2010-11-12 doi: 10.3390/ma3114922 Peter G. Loutzenhiser Anton Meier Aldo Steinfeld http://www.mdpi.com/1996-1944/3/11/4915/ Organic thin-film solar cells with a conducting polymer (CP)/fullerene (C60) interpenetrating heterojunction structure, fabricated by spin-coating a CP onto a C60 deposit thin film, have been investigated and demonstrated to have high efficiency. The photovoltaic properties of solar cells with a structure of indium-tin-oxide/C60/ poly(3-hexylthiophene) (PAT6)/Au have been improved by the insertion of molybdenum trioxide (VI) (MoO3) and zinc oxide charge transport buffer layers. The enhanced photovoltaic properties have been discussed, taking into consideration the ground-state charge transfer between PAT6 and MoO3 by measurement of the differential absorption spectra and the suppressed contact resistance at the interface between the organic and buffer layers. http://www.mdpi.com/1996-1944/3/11/4915/ Mon, 08 Nov 2010 00:00:00 CET Materials 2010-11-08 3 11 Article 4915 4921 1996-1944 Photovoltaic Properties in Interpenetrating Heterojunction Organic Solar Cells Utilizing MoO3 and ZnO Charge Transport Buffer Layers 2010-11-08 doi: 10.3390/ma3114915 Tetsuro Hori Hiroki Moritou Naoki Fukuoka Junki Sakamoto Akihiko Fujii Masanori Ozaki http://www.mdpi.com/1996-1944/3/11/4892/ Doping limits, band gaps, work functions and energy band alignments of undoped and donor-doped transparent conducting oxides Zn0, In2O3, and SnO2 as accessed by X-ray and ultraviolet photoelectron spectroscopy (XPS/UPS) are summarized and compared. The presented collection provides an extensive data set of technologically relevant electronic properties of photovoltaic transparent electrode materials and illustrates how these relate to the underlying defect chemistry, the dependence of surface dipoles on crystallographic orientation and/or surface termination, and Fermi level pinning. http://www.mdpi.com/1996-1944/3/11/4892/ Tue, 02 Nov 2010 00:00:00 CET Materials 2010-11-02 3 11 Article 4892 4914 1996-1944 Transparent Conducting Oxides for Photovoltaics: Manipulation of Fermi Level, Work Function and Energy Band Alignment 2010-11-02 doi: 10.3390/ma3114892 Andreas Klein Christoph Körber André Wachau Frank Säuberlich Yvonne Gassenbauer Steven P. Harvey Diana E. Proffit Thomas O. Mason http://www.mdpi.com/1996-1944/3/10/4773/ The postfunctionalization of the main chain alkyne moieties of carbazole containing poly(arylenebutadiynylene)s was attempted by using a high yielding addition reaction between electron rich alkynes and a strong acceptor molecule, tetracyanoethylene (TCNE). After successful postfunctionalization, the polymer band gap decreased due to the intramolecular donor-acceptor interactions. The resulting donor-acceptor alternating polymer showed a very broad charge-transfer band in the visible region as well as redox activities in both anodic and cathodic directions. The optical band gap showed good agreement with the electrochemical band gap. Furthermore, the thermal stability was enhanced after postfunctionalization. These features of the donor-acceptor alternating polymer are expected to be useful for high performance activities in organic solar cell applications. http://www.mdpi.com/1996-1944/3/10/4773/ Fri, 15 Oct 2010 00:00:00 CEST Materials 2010-10-15 3 10 Article 4773 4783 1996-1944 Postfunctionalization of Alkyne-Linked Conjugated Carbazole Polymer by Thermal Addition Reaction of Tetracyanoethylene 2010-10-15 doi: 10.3390/ma3104773 Tsuyoshi Michinobu Hiroyuki Fujita