International Journal of Photoenergy http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. An Improved Fuzzy Logic Controller Design for PV Inverters Utilizing Differential Search Optimization Wed, 22 Oct 2014 11:31:04 +0000 http://www.hindawi.com/journals/ijp/2014/469313/ This paper presents an adaptive fuzzy logic controller (FLC) design technique for photovoltaic (PV) inverters using differential search algorithm (DSA). This technique avoids the exhaustive traditional trial and error procedure in obtaining membership functions (MFs) used in conventional FLCs. This technique is implemented during the inverter design phase by generating adaptive MFs based on the evaluation results of the objective function formulated by the DSA. In this work, the mean square error (MSE) of the inverter output voltage is used as an objective function. The DSA optimizes the MFs such that the inverter provides the lowest MSE for output voltage and improves the performance of the PV inverter output in terms of amplitude and frequency. The design procedure and accuracy of the optimum FLC are illustrated and investigated using simulations conducted for a 3 kW three-phase inverter in a MATLAB/Simulink environment. Results show that the proposed controller can successfully obtain the desired output when different linear and nonlinear loads are connected to the system. Furthermore, the inverter has reasonably low steady state error and fast response to reference variation. Ammar Hussein Mutlag, Hussain Shareef, Azah Mohamed, M. A. Hannan, and Jamal Abd Ali Copyright © 2014 Ammar Hussein Mutlag et al. All rights reserved. Enhancing the Efficiency of Polymer Solar Cells by Modifying Buffer Layer with N,N-Dimethylacetamide Mon, 20 Oct 2014 00:00:00 +0000 http://www.hindawi.com/journals/ijp/2014/854749/ We modified the PEDOT:PSS anode buffer layer in P3HT:PCBM bulk heterojunction polymer solar cells by spin-coating the solvent N,N-dimethylacetamide (DMAC). This modification significantly enhanced the efficiency of the ITO/PEDOT:PSS/DMAC/P3HT:PCBM/LiF/Al solar cells. The DMAC-treated device spin-coated at 3000 rpm exhibited a power conversion efficiency (PCE) of 3.74%, a 59% improvement over that of an untreated cell. To study the mechanism of improving the conversion efficiency, we characterized many parameters, including the light and dark I-V curves, external quantum efficiency, active layer absorption spectrum, transmission spectrum of ITO:PEDOTPSS, PEDOT:PSS surface morphology, and electrical conductivity. Modifying the PEDOT:PSS film increased conductivity, making it more conducive to hole extraction and collection. Our findings suggest that modifying the anode buffer layer can improve photoelectric conversion efficiency. Shaopeng Yang, Xuefeng Sun, Ye Zhang, Guang Li, Xiaohui Zhao, Xiaowei Li, and Guangsheng Fu Copyright © 2014 Shaopeng Yang et al. All rights reserved. Facile Synthesis of Micron-Sized Hollow Silver Spheres as Substrates for Surface-Enhanced Raman Scattering Sun, 19 Oct 2014 13:45:58 +0000 http://www.hindawi.com/journals/ijp/2014/745913/ A well-designed type of micron-sized hollow silver sphere was successfully synthesized by a simple hard-template method to be used as substrates for surface-enhanced Raman scattering. 4 Å molecular sieves were employed as a removable solid template. [Ag(NH3)2]+ was absorbed as the precursor on the surface of the molecular sieve. Formaldehyde was selected as a reducing agent to reduce [Ag(NH3)2]+, resulting in the formation of a micron-sized silver shell on the surface of the 4 Å molecular sieves. The micron-sized hollow silver spheres were obtained by removing the molecular sieve template. SEM and XRD were used to characterize the structure of the micron-sized hollow silver spheres. The as-prepared micro-silver spheres exhibited robust SERS activity in the presence of adsorbed 4-mercaptobenzoic acid (4-MBA) with excitation at 632.8 nm, and the enhancement factor reached ~1.5 × 106. This synthetic process represents a promising method for preparing various hollow metal nanoparticles. Lixin Xia, Jiarui Xia, Ran Wei, Ying Sui, Zhipeng Sun, Xuehua Song, Peng Song, and Lini Yang Copyright © 2014 Lixin Xia et al. All rights reserved. Enhanced Transformation of Atrazine by High Efficient Visible Light-Driven N, S-Codoped TiO2 Nanowires Photocatalysts Sun, 19 Oct 2014 00:00:00 +0000 http://www.hindawi.com/journals/ijp/2014/425836/ Advanced oxidation process using titanium dioxide as a photocatalyst under solar irradiation is one of the most attractive technologies to eliminate atrazine, an endocrine disrupting and carcinogen contaminant. The N, S-codoped TiO2 nanowires at the calcination of 600°C obtained by a facile hydrothermal method revealed the best photocatalytic performance for the degradation of atrazine under visible light irradiation compared to N, S-codoped TiO2 nanoparticles and S-doped TiO2 nanowires. TOC removal experiment also exhibited the similar result and achieved 63% of atrazine mineralization within 6 h. The degradation of atrazine was driven mainly by •OH and holes during the photocatalytic process. Reactive species quantities such •OH and generated by N, S-codoped TiO2 nanowires under visible light irradiation were much more than those of S-doped TiO2 nanowires and N, S-codoped TiO2 nanoparticles. These results were mainly attributed to the synergistic effect of N and S doping in narrowing the band gap, remarkable increase in electron-hole separation, extending the anatase-to-rutile transformation temperature above 600°C, and preferentially exposing high reactive crystal facets of anatase. Yanlin Zhang, Honghai Wu, and Peihong Liu Copyright © 2014 Yanlin Zhang et al. All rights reserved. Mixing Rules Formulation for a Kinetic Model of the Langmuir-Hinshelwood Semipredictive Type Applied to the Heterogeneous Photocatalytic Degradation of Multicomponent Mixtures Thu, 16 Oct 2014 14:18:11 +0000 http://www.hindawi.com/journals/ijp/2014/817538/ Mixing rules coupled to a semipredictive kinetic model of the Langmuir-Hinshelwood type were proposed to determine the behavior of the heterogeneous solar photodegradation with TiO2-P25 of multicomponent mixtures at pilot scale. The kinetic expressions were expressed in terms of the effective concentration of total organic carbon . An expression was obtained in a generalized form which is a function of the mixing rules as a product of a global contribution of the reaction rate constant and a mixing function . Kinetic parameters of the model were obtained using the Nelder and Mead (N-M) algorithm. The kinetic model was validated with experimental data obtained from the degradation of binary mixtures of chlorinated compounds (DCA: dichloroacetic acid and 4-CP: 4-chlorophenol) at different initial global concentration, using a CPC reactor at pilot scale. A simplex-lattice design experiment was adopted to perform the runs. John Wilman Rodriguez-Acosta, Miguel Ángel Mueses, and Fiderman Machuca-Martínez Copyright © 2014 John Wilman Rodriguez-Acosta et al. All rights reserved. Destruction of Toluene by the Combination of High Frequency Discharge Electrodeless Lamp and Manganese Oxide-Impregnated Granular Activated Carbon Catalyst Mon, 13 Oct 2014 12:41:01 +0000 http://www.hindawi.com/journals/ijp/2014/365862/ The destruction of low concentration of toluene (0–30 ppm) has been studied under the UV/photogenerated O3/MnO2-impregnated granular activated carbon (MnO2-impregnated GAC) process by the combination of self-made high frequency discharge electrodeless lamp (HFDEL) with MnO2-impregnated GAC catalyst. Experimental results showed that the initial toluene concentration can strongly affect the concentration of photogenerated O3 from HFDEL and the efficiency and mass rate of destruction of toluene via HFDEL/MnO2-impregnated GAC system. Active oxygen and hydroxyl radicals generated from HFDEL/MnO2-impregnated GAC system played a key role in the decomposition of toluene process and the intermediates formed by photolysis are more prone to be mineralized by the subsequent MnO2-impregnated GAC catalyst compared to the original toluene, resulting in synergistic mineralization of toluene by HFDEL/MnO2-impregnated GAC system. The role of MnO2-impregnated GAC catalyst is not only to eliminate the residual O3 completely but also to enhance the decomposition and mineralization of toluene. Jianhui Xu, Chaolin Li, Qian Zhang, Di He, Peng Liu, and Yong Ren Copyright © 2014 Jianhui Xu et al. All rights reserved. Solar Hydrogen Production Coupled with the Degradation of a Dye Pollutant Using TiO2 Modified with Platinum and Nafion Mon, 13 Oct 2014 08:12:31 +0000 http://www.hindawi.com/journals/ijp/2014/324859/ The simultaneous production of molecular hydrogen (H2) and degradation of rhodamine B (RhB) was successfully achieved using TiO2 modified with platinum and nafion (Pt/TiO2/Nf) under visible light  nm). Pt/TiO2/Nf exhibited high activity for H2 production in the presence of RhB and EDTA as a photosensitizer (also an organic dye pollutant) and an electron donor, respectively. However, the activity of TiO2 modified with either platinum or nafion for H2 production was negligible under the same experimental conditions. The negatively charged nafion layer enhances the adsorption of cationic RhB and pulls protons, a source of hydrogen, to the surface of TiO2 through electrostatic attraction. On the other hand, platinum deposits on TiO2 can act as an electron sink and a temporary electron reservoir for the reduction of protons. With the production of H2, RhB was gradually degraded through -deethylation, which was confirmed by the spectral blue shift of the maximum absorption wavelength from 556 to 499 nm (corresponding to the of rhodamine 110). With Pt/TiO2/Nf employed at  M (0.6 mol), approximately 70 mol of H2 was produced and RhB and its intermediates were completely removed over a 12 h period. A detailed reaction mechanism was discussed. Jungwon Kim, Yiseul Park, and Hyunwoong Park Copyright © 2014 Jungwon Kim et al. All rights reserved. Preparation of Ni Doped ZnO-TiO2 Composites and Their Enhanced Photocatalytic Activity Mon, 13 Oct 2014 06:34:49 +0000 http://www.hindawi.com/journals/ijp/2014/893158/ Herein, Ni doped ZnO-TiO2 composites were prepared by facile sol-gel approach and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), X-ray photoelectron spectroscopy (XPS), and photoluminescence spectroscopy (PL). The results indicated that the Ni ions can be incorporated into the lattice of TiO2 structure and replace Ti. The introduction of Ni expanded light absorption of TiO2 to visible region, increased amount of surface hydroxyl groups and physically adsorbed oxygen (as the electronic scavenges), and then enhanced separation rate of photogenerated carriers. The photodegradation test of reactive brilliant blue (KN-R) under simulated solar light indicated that Ni doped ZnO-TiO2 composites have better photocatalytic activities, as compared to those of TiO2 and ZnO-TiO2. Xiaowen Zou, Xiaoli Dong, Limei Wang, Hongchao Ma, Xinxin Zhang, and Xiufang Zhang Copyright © 2014 Xiaowen Zou et al. All rights reserved. Metal/Semiconductor and Transparent Conductor/Semiconductor Heterojunctions in High Efficient Photoelectric Devices: Progress and Features Mon, 22 Sep 2014 06:17:06 +0000 http://www.hindawi.com/journals/ijp/2014/160379/ Metal/semiconductor and transparent conductive oxide (TCO)/semiconductor heterojunctions have emerged as an effective modality in the fabrication of photoelectric devices. This review is following a recent shift toward the engineering of TCO layers and structured Si substrates, incorporating metal nanoparticles for the development of next-generation photoelectric devices. Beneficial progress which helps to increase the efficiency and reduce the cost, has been sequenced based on efficient technologies involved in making novel substrates, TCO layers, and electrodes. The electrical and optical properties of indium tin oxide (ITO) and aluminum doped zinc oxide (AZO) thin films can be enhanced by structuring the surface of TCO layers. The TCO layers embedded with Ag nanoparticles are used to enhance the plasmonic light trapping effect in order to increase the energy harvesting nature of photoelectric devices. Si nanopillar structures which are fabricated by photolithography-free technique are used to increase light-active surface region. The importance of the structure and area of front electrodes and the effect of temperature at the junction are the value added discussions in this review. M. Melvin David Kumar, Ju-Hyung Yun, and Joondong Kim Copyright © 2014 M. Melvin David Kumar et al. All rights reserved. Fabrication and Characterization of Dye-Sensitized Solar Cells for Greenhouse Application Mon, 08 Sep 2014 00:00:00 +0000 http://www.hindawi.com/journals/ijp/2014/376315/ We have developed dye-sensitized solar cells using novel sensitizers with enhanced transmittance of red (625–675 nm) and blue (425–475 nm) wavebands to control the illumination condition in the greenhouse. Novel ruthenium bipyridyl sensitizers with general formulas (Me3PhN)4[Ru(dcbpy)2(NCS)2] (JJ-7) and (Me3BnN)4[Ru(dcbpy)2(NCS)2] (JJ-9) have been synthesized and demonstrated as efficient sensitizers in dye-sensitized solar cells for greenhouse application. Under standard AM 1.5 sunlight, the solar cell of JJ-7 using a liquid-based electrolyte exhibits a short-circuit photocurrent density of 8.49 mA/cm2, an open-circuit voltage of 0.83 V, and a fill factor of 0.71, corresponding to an overall conversion efficiency of 4.96% on 5 m TiO2 film. The transmittance of JJ-7 and JJ-9 shows 62.0% and 61.0% at 660 nm and 18.0% and 15.0% at 440 nm for cultivation on 5 m TiO2 film, respectively. Jeum-Jong Kim, Mangu Kang, Ock Keum Kwak, Yong-Jin Yoon, Kil Sik Min, and Moo-Jung Chu Copyright © 2014 Jeum-Jong Kim et al. All rights reserved. Efficiency Enhancement of Nanoporous Silicon/Polycrystalline-Silicon Solar Cells by Application of Trenched Electrodes Sun, 07 Sep 2014 11:48:06 +0000 http://www.hindawi.com/journals/ijp/2014/307643/ Trenched electrodes were proposed to enhance the short-circuit current and conversion efficiency of polycrystalline-silicon (poly-Si) solar cells with nanoporous silicon (NPS) surface layers. NPS films that served as textured surface layers were firstly prepared on heavily doped p+-type (100) poly-Si wafers by anodic etching process. Interdigitated trenches were formed in the NPS layers by a reactive-ion-etch (RIE) process and Cr/Al double-layered metal was then deposited to fill the trenches and construct trenched-electrode-contacts (TEC’s). Cells with TEC structures (called “TEC cells”) obtained 5.5 times higher short-circuit current than that of cells with planar electrode contacts (called “non-TEC cells”). Most significantly, a TEC cell achieved 8 times higher conversion efficiency than that of a non-TEC cell. The enhanced short-circuit current and conversion efficiency in TEC cells were ascribed to the reduced overall series resistance of devices. In a TEC cell, trenched electrodes provided photocurrent flowing routes that directly access the poly-Si substrates without passing through the high resistive NPS layers. Therefore, the application of NPS surface layers with trenched electrodes is a novel approach to development of highly efficient poly-Si solar cells. Kuen-Hsien Wu and Chia-Chun Tang Copyright © 2014 Kuen-Hsien Wu and Chia-Chun Tang. All rights reserved. An Innovative Application of a Solar Storage Wall Combined with the Low-Temperature Organic Rankine Cycle Sun, 07 Sep 2014 09:10:01 +0000 http://www.hindawi.com/journals/ijp/2014/239137/ The objective of this study is to collect energy on the waste heat from air produced by solar ventilation systems. This heat used for electricity generation by an organic Rankine cycle (ORC) system was implemented. The advantages of this method include the use of existing building’s wall, and it also provides the region of energy scarcity for reference. This is also an innovative method, and the results will contribute to the efforts made toward improving the design of solar ventilation in the field of solar thermal engineering. In addition, ORC system would help generate electricity and build a low-carbon building. This study considered several critical parameters such as length of the airflow channel, intensity of solar radiation, pattern of the absorber plate, stagnant air layer, and operating conditions. The simulation results show that the highest outlet temperature and heat collecting efficiency of solar ventilation system are about 120°C and 60%, respectively. The measured ORC efficiency of the system was 6.2%. The proposed method is feasible for the waste heat from air produced by ventilation systems. Tzu-Chen Hung, Duen-Sheng Lee, and Jaw-Ren Lin Copyright © 2014 Tzu-Chen Hung et al. All rights reserved. Solid-State Lighting with High Brightness, High Efficiency, and Low Cost Sun, 07 Sep 2014 08:15:41 +0000 http://www.hindawi.com/journals/ijp/2014/278263/ Ray-Hua Horng, Kei May Lau, Hao-Chung Kuo, and Nelson Tansu Copyright © 2014 Ray-Hua Horng et al. All rights reserved. Detailed Photoisomerization Dynamics of a Green Fluorescent Protein Chromophore Based Molecular Switch Wed, 03 Sep 2014 05:50:08 +0000 http://www.hindawi.com/journals/ijp/2014/597165/ With density-functional-based nonadiabatic molecular dynamics simulations, trans-to-cis and cis-to-trans photoisomerizations of a green fluorescent protein chromophore based molecule 4-benzylidene-2-methyloxazol-5(4H)-one (BMH) induced by the excitation to its excited state were performed. We find a quantum yield of 32% for the trans-to-cis photoisomerization of BMH and a quantum yield of 33% for its cis-to-trans photoisomerization. For those simulations that did produce trans-to-cis isomerization, the average excited state lifetime of trans-BMH is about 1460 fs, which is much shorter than that of cis-BMH (3100 fs) in those simulations that did produce cis-to-trans isomerization. For both photoisomerization processes, rotation around the central C2=C3 bond is the dominant reaction mechanism. Deexcitation occurs at an avoided crossing near the / conical intersection, which is near the midpoint of the rotation. Chen-Wei Jiang, Ai-Ping Fang, Di Zhao, Hong-Rong Li, Rui-Hua Xie, and Fu-Li Li Copyright © 2014 Chen-Wei Jiang et al. All rights reserved. Visible-Light Degradation of Dyes and Phenols over Mesoporous Titania Prepared by Using Anthocyanin from Red Radish as Template Tue, 02 Sep 2014 11:07:50 +0000 http://www.hindawi.com/journals/ijp/2014/968298/ Heterogeneous photocatalysis is able to operate effectively to eliminate organic compounds from wastewater in the presence of semiconductor photocatalyst and a light source. Although photosensitization of titania by organic dyes is one of the conventional ways for visible-light utilization of titania, previous studies have not yet addressed the use of natural food coloring agents as templates in the synthesis of mesostructured materials, let alone the simultaneous achievement of highly crystalline mesoscopic framework and visible-light photocatalytic activity. In this work, anthocyanin, a natural pigment from red radish was directly used as template in synthesis of highly crystalline mesoporous titania. The synthesized mesoporous titania samples were characterized by a combination of various physicochemical techniques, such as XRD, SEM, HRTEM, nitrogen adsorption/desorption, and diffuse reflectance UV-Vis. The prepared mesoporous titania photocatalyst exhibited significant activity under visible-light irradiation for the degradation of dyes and phenols due to its red shift of band-gap-absorption onset and visible-light response as a result of the incorporation of surface carbon species. Zhiying Yan, Wenjuan Gong, Yongjuan Chen, Deliang Duan, Junjie Li, Wei Wang, and Jiaqiang Wang Copyright © 2014 Zhiying Yan et al. All rights reserved. Evaluation of Fuzzy Logic Subsets Effects on Maximum Power Point Tracking for Photovoltaic System Tue, 02 Sep 2014 00:00:00 +0000 http://www.hindawi.com/journals/ijp/2014/719126/ Photovoltaic system (PV) has nonlinear characteristics which are affected by changing the climate conditions and, in these characteristics, there is an operating point in which the maximum available power of PV is obtained. Fuzzy logic controller (FLC) is the artificial intelligent based maximum power point tracking (MPPT) method for obtaining the maximum power point (MPP). In this method, defining the logical rule and specific range of membership function has the significant effect on achieving the best and desirable results. This paper presents a detailed comparative survey of five general and main fuzzy logic subsets used for FLC technique in DC-DC boost converter. These rules and specific range of membership functions are implemented in the same system and the best fuzzy subset is obtained from the simulation results carried out in MATLAB. The proposed subset is able to track the maximum power point in minimum time with small oscillations and the highest system efficiency (95.7%). This investigation provides valuable results for all users who want to implement the reliable fuzzy logic subset for their works. Shahrooz Hajighorbani, M. A. M. Radzi, M. Z. A. Ab Kadir, S. Shafie, Razieh Khanaki, and M. R. Maghami Copyright © 2014 Shahrooz Hajighorbani et al. All rights reserved. Pyran-Squaraine as Photosensitizers for Dye-Sensitized Solar Cells: DFT/TDDFT Study of the Electronic Structures and Absorption Properties Mon, 01 Sep 2014 12:31:39 +0000 http://www.hindawi.com/journals/ijp/2014/136893/ In an effort to provide, assess, and evaluate a theoretical approach which enables designing efficient donor-acceptor dye systems, the electronic structure and optical properties of pyran-squaraine as donor-acceptor dyes used in dye-sensitized solar cells were investigated. Ground state properties have been computed at the B3LYP/6-31+ level of theory. The long-range corrected density functionals CAM-B3LYP, PBEPBE, PBE1PBE (PBE0), and TPSSH with 6-311++ were employed to examine absorption properties of the studied dyes. In an extensive comparison between experimental results and ab initio benchmark calculations, the TPSSH functional with 6-311++ basis set was found to be the most appropriate in describing the electronic properties for the studied pyran and squaraine dyes. Natural transition orbitals (NTO), frontier molecular orbitals (FMO), LUMO, HOMO, and energy gaps, of these dyes, have been analyzed to show their effect on the process of electron injection and dye regeneration. Interaction between HOMO and LUMO of pyran and squaraine dyes was investigated to understand the recombination process and charge-transfer process involving these dyes. Additionally, we performed natural bond orbital (NBO) analysis to investigate the role of charge delocalization and hyperconjugative interactions in the stability of the molecule. Reda M. El-Shishtawy, Shaaban A. Elroby, Abdullah M. Asiri, and Rifaat H. Hilal Copyright © 2014 Reda M. El-Shishtawy et al. All rights reserved. Experiment Investigation on Electrical and Thermal Performances of a Semitransparent Photovoltaic/Thermal System with Water Cooling Mon, 01 Sep 2014 05:51:05 +0000 http://www.hindawi.com/journals/ijp/2014/360235/ Different from the semitransparent building integrated photovoltaic/thermal (BIPV/T) system with air cooling, the semitransparent BIPV/T system with water cooling is rare, especially based on the silicon solar cells. In this paper, a semitransparent photovoltaic/thermal system (SPV/T) with water cooling was set up, which not only would provide the electrical power and hot water, but also could attain the natural illumination for the building. The PV efficiency, thermal efficiency, and exergy analysis were all adopted to illustrate the performance of SPV/T system. The results showed that the PV efficiency and the thermal efficiency were about 11.5% and 39.5%, respectively, on the typical sunny day. Furthermore, the PV and thermal efficiencies fit curves were made to demonstrate the SPV/T performance more comprehensively. The performance analysis indicated that the SPV/T system has a good application prospect for building. Guiqiang Li, Gang Pei, Ming Yang, and Jie Ji Copyright © 2014 Guiqiang Li et al. All rights reserved. Growth and Properties of ZnO:Al on Textured Glass for Thin Film Solar Cells Thu, 28 Aug 2014 15:25:38 +0000 http://www.hindawi.com/journals/ijp/2014/406495/ Aluminium induced texturing (AIT) method has been used to texture glass substrates in order to enhance the photon absorption in thin film solar cells. The resultant glass roughness has been analyzed by varying the AIT process parameters and it has been found that the deposition method of Al is a decisive factor in tuning the texture. Two types of textures, a soft (texture E) and a rough texture (texture S), were achieved from the thermally evaporated and sputtered Al layers through AIT process. Aluminium-doped zinc oxide (AZO) layers of different thickness were deposited over both textures and over smooth glass. Haze values above 30% were obtained for texture S + AZO and above 10% for texture E + AZO. The resultant morphologies were free from sharp edges or deep valleys and the transparency and the resistivity values were also good enough to be used as front contact for thin film solar cells. In order to demonstrate the light absorption enhancement in a solar cell device, 200 nm of a-Si:H followed by 300 nm of Ag were grown over the textured and smooth substrates with AZO, and an optical absorption enhancement of 35% for texture E and 53% for texture S was obtained in comparison to the smooth substrate. Marta Lluscà, Aldrin Antony, and Joan Bertomeu Copyright © 2014 Marta Lluscà et al. All rights reserved. Preparation, Characterization, and Photocatalytic Applications of MWCNTs/TiO2 Composite Thu, 28 Aug 2014 15:10:15 +0000 http://www.hindawi.com/journals/ijp/2014/475713/ The multiwall carbon nanotubes (MWCNTs)/titanium dioxide (P25) composite in different ratios was prepared using simple evaporation and drying process. The composite was characterized by Raman spectroscopy, X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy, and scanning electron microscopy (SEM). The photocatalytic activity of this composite was investigated using degradation of the Bismarck brown R dye (BBR). An optimal MWCNTs/TiO2 ratio of 0.5% (w/w) was found to achieve the maximum rate of BBR degradation. It was observed that the composite exhibits enhanced photocatalytic activity compared with TiO2. The enhancement in photocatalytic activity performance of the MWCNTs/P25 composite is explained in terms of recombination of photogenerated electron-hole pairs. In addition, MWCNTs act as a dispersing support to control the morphology of TiO2 particles in the MWCNTs/TiO2 composite. Ahmed M. Kamil, Falah H. Hussein, Ahmed F. Halbus, and Detlef W. Bahnemann Copyright © 2014 Ahmed M. Kamil et al. All rights reserved. Bridging Photonics and Optoelectronics Curriculum for the Solar Photovoltaic and LED Industries Thu, 28 Aug 2014 15:05:00 +0000 http://www.hindawi.com/journals/ijp/2014/146810/ The gap between learning courses and practical demands has existed in Taiwanese solar photovoltaic and LED industries; therefore, this study attempts to analyze the existing curriculum design of universities. This study collected the current 103 course programs from all optoelectronics-related departments in Taiwanese 36 colleges and universities and sorted these curriculums by three domains of education objectives theory. This theoretical framework was verified on the basis of samples from 150 Taiwanese industrial experts and 354 optoelectronics-related undergraduates and postgraduates. We found that the levels of correlation among the independent variables including cognitive, affective, and skill-based domains and the dependent variable employability are all positively related to each other. We also found the currently curriculum design in Taiwanese universities rarely fit into theory of education objectives from the results of multiple regression analysis. Industrial and student’s group also have few consistent ideas on courses within the curriculum. Finally in order to bridge the gap between learning and practical application, the study provides an idea on curriculum design and suggests that curriculum review should be executed by industrial experts to confirm the courses related to the employability. Yu-Shan Su and Han-Chao Chang Copyright © 2014 Yu-Shan Su and Han-Chao Chang. All rights reserved. Study of an Amorphous Silicon Oxide Buffer Layer for p-Type Microcrystalline Silicon Oxide/n-Type Crystalline Silicon Heterojunction Solar Cells and Their Temperature Dependence Thu, 28 Aug 2014 11:34:36 +0000 http://www.hindawi.com/journals/ijp/2014/251508/ Intrinsic hydrogenated amorphous silicon oxide (i-a-SiO:H) films were used as front and rear buffer layers in crystalline silicon heterojunction (c-Si-HJ) solar cells. The surface passivity and effective lifetime of these i-a-SiO:H films on an n-type silicon wafer were improved by increasing the CO2/SiH4 ratios in the films. Using i-a-SiO:H as the front and rear buffer layers in c-Si-HJ solar cells was investigated. The front i-a-SiO:H buffer layer thickness and the CO2/SiH4 ratio influenced the open-circuit voltage , fill factor (FF), and temperature coefficient (TC) of the c-Si-HJ solar cells. The highest total area efficiency obtained was 18.5%  mV,  mA/cm2, and . The TC normalized for this c-Si-HJ solar cell efficiency was −0.301%/°C. Taweewat Krajangsang, Apichan Moollakorn, Sorapong Inthisang, Amornrat Limmanee, Kobsak Sriprapha, Nattaphong Boriraksantikul, Tianchai Taratiwat, Nirod Akarapanjavit, and Jaran Sritharathikhun Copyright © 2014 Taweewat Krajangsang et al. All rights reserved. Experiment and Simulation Study on the Amorphous Silicon Photovoltaic Walls Wed, 27 Aug 2014 08:13:04 +0000 http://www.hindawi.com/journals/ijp/2014/643637/ Based on comparative study on two amorphous silicon photovoltaic walls (a-Si PV walls), the temperature distribution and the instant power were tested; and with EnergyPlus software, similar models of the walls were built to simulate annual power generation and air conditioning load. On typical sunshine day, the corresponding position temperature of nonventilated PV wall was generally 0.5~1.5°C higher than that of ventilated one, while the power generation was 0.2%~0.4% lower, which was consistent with the simulation results with a difference of 0.41% in annual energy output. As simulation results, in summer, comparing the PV walls with normal wall, the heat per unit area of these two photovoltaic walls was 5.25 kWh/m2 (nonventilated) and 0.67 kWh/m2 (ventilated) higher, respectively. But in winter the heat loss of nonventilated one was smaller, while ventilated PV wall was similar to normal wall. To annual energy consumption of heating and cooling, the building with ventilated PV wall and normal wall was also similar but slightly better than nonventilated one. Therefore, it is inferred that, at low latitudes, such as Zhuhai, China, air gap ventilation is suitable, while the length to thickness ratio of the air gap needs to be taken into account. Wenjie Zhang, Bin Hao, and Nianping Li Copyright © 2014 Wenjie Zhang et al. All rights reserved. J-Aggregates of Amphiphilic Cyanine Dyes for Dye-Sensitized Solar Cells: A Combination between Computational Chemistry and Experimental Device Physics Tue, 26 Aug 2014 08:52:10 +0000 http://www.hindawi.com/journals/ijp/2014/579476/ We report on the design and structure principles of 5,5′-6,6′-tetrachloro-1,1′-dioctyl-3,3′-bis-(3-carboxypropyl)-benzimidacarbocyanine (Dye 1). Such metal-free amphiphilic cyanine dyes have many applications in dye-sensitized solar cells. AFM surface topographic investigation of amphiphilic molecules of Dye 1 adsorbed on TiO2 anode reveals the ability of spontaneous self-organization into highly ordered aggregates of fiber-like structure. These aggregates are known to exhibit outstanding optical properties of J-aggregates, namely, efficient exciton coupling and fast exciton energy migration, which are essential for building up artificial light harvesting to the photovoltaic device. A light-to-electricity conversion efficiency of DSSC based on the metal free amphiphilic Dye 1 is , which is about 50% of that based on metal-based N719 Ru-dye (Di-tetrabutylammoniumcis-bis(isothiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato)ruthenium(II)). DFT and TD-DFT studies show that large intramolecular charge transfer takes place from the HOMO to LUMO. HOMO is localized on a part of the molecule with almost no contribution from the carboxylic moiety. This clearly indicates that the anchoring carboxylic group plays a minor role. M. S. A. Abdel-Mottaleb, Mohamed M. S. Abdel-Mottaleb, Hoda S. Hafez, and Mona Saif Copyright © 2014 M. S. A. Abdel-Mottaleb et al. All rights reserved. Band-Gap Engineering of NaNbO3 for Photocatalytic H2 Evolution with Visible Light Tue, 26 Aug 2014 08:26:52 +0000 http://www.hindawi.com/journals/ijp/2014/380421/ A new visible light response photocatalyst has been developed for H2 evolution from methanol solution by elemental doping. With lanthanum and cobalt dopants, the photoabsorption edge of NaNbO3 was effectively shifted to the visible light region. It is also found that the photoabsorption edge is effectively controlled by the dopant concentration. Under visible light irradiation, H2 was successfully generated over the doped NaNbO3 samples and a rate of 12 μmol·h−1 was achieved over (LaCo)0.03(NaNb)0.97O3. Densityfunctional theory calculations show that Co-induced impurity states are formed in the band gap of NaNbO3 and this is considered to be the origin of visible-light absorption upon doping with La and Co. Peng Li, Hideki Abe, and Jinhua Ye Copyright © 2014 Peng Li et al. All rights reserved. Effect of Aging Time and Film Thickness on the Photoelectrochemical Properties of TiO2 Sol-Gel Photoanodes Mon, 25 Aug 2014 08:41:40 +0000 http://www.hindawi.com/journals/ijp/2014/472539/ This work has focused on the investigation of a non-aqueous based sol-gel process to produce TiO2 based photoelectrodes for solar water splitting. In particular, the effect of the aging time of the sol and TiO2 film thickness on the photoelectrochemical properties of the photoanodes has been investigated. In order to achieve optimal performances (i.e., photocurrent density up to 570 µA/cm2 and IPCE of 26% at 300 nm), the sol needs to be aged for 3 to 6 h, before being dip-coated to produce the photoanodes. The importance of the aging time can also be appreciated from the optical properties of the TiO2 films; the absorbance threshold of the sol-gel aged for 3–6 h is slightly shifted towards longer wavelenghts in comparison to 0 h aging. Aging is necessary to build up a well-interconnected sol-gel network which finally leads to a photoelectrode with optimized light absorption and electron collection properties. This is also confirmed by the higher IPCE signal of aged photoelectrodes, especially below 340 nm. Among thicknesses considered, there is no apparent significant difference in the photoresponse (photocurrent density and IPCE) of the TiO2 sol-gel films. D. Regonini, A. K. Alves, F. A. Berutti, and F. Clemens Copyright © 2014 D. Regonini et al. All rights reserved. Heterojunction Solar Cells Sun, 24 Aug 2014 10:37:52 +0000 http://www.hindawi.com/journals/ijp/2014/163984/ Aung Ko Ko Kyaw, Antonio Otavio T. Patrocinio, Dewei Zhao, and Victor Brus Copyright © 2014 Aung Ko Ko Kyaw et al. All rights reserved. Reactive Power Control of Single-Stage Three-Phase Photovoltaic System during Grid Faults Using Recurrent Fuzzy Cerebellar Model Articulation Neural Network Sun, 24 Aug 2014 09:38:11 +0000 http://www.hindawi.com/journals/ijp/2014/760743/ This study presents a new active and reactive power control scheme for a single-stage three-phase grid-connected photovoltaic (PV) system during grid faults. The presented PV system utilizes a single-stage three-phase current-controlled voltage-source inverter to achieve the maximum power point tracking (MPPT) control of the PV panel with the function of low voltage ride through (LVRT). Moreover, a formula based on positive sequence voltage for evaluating the percentage of voltage sag is derived to determine the ratio of the injected reactive current to satisfy the LVRT regulations. To reduce the risk of overcurrent during LVRT operation, a current limit is predefined for the injection of reactive current. Furthermore, the control of active and reactive power is designed using a two-dimensional recurrent fuzzy cerebellar model articulation neural network (2D-RFCMANN). In addition, the online learning laws of 2D-RFCMANN are derived according to gradient descent method with varied learning-rate coefficients for network parameters to assure the convergence of the tracking error. Finally, some experimental tests are realized to validate the effectiveness of the proposed control scheme. Faa-Jeng Lin, Kuang-Chin Lu, and Hsuan-Yu Lee Copyright © 2014 Faa-Jeng Lin et al. All rights reserved. An Improved Matlab-Simulink Model of PV Module considering Ambient Conditions Sun, 24 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/ijp/2014/315893/ A photovoltaic (PV) model is proposed on Matlab/Simulink environment considering the real atmospheric conditions and this PV model is tested with different PV panels technologies (monocrystalline silicon, polycrystalline silicon, and thin film). The meteorological data of Istanbul—the location of the study—such as irradiance, cell temperature, and wind speed are taken into account in the proposed model for each technology. Eventually, the power outputs of the PV module under real atmospheric conditions are measured for resistive loading and these powers are compared with the results of proposed PV model. As a result of the comparison, it is shown that the proposed model is more compatible for monocrystal silicon and thin-film modules; however, it does not show a good correlation with polycrystalline silicon PV module. R. Ayaz, I. Nakir, and M. Tanrioven Copyright © 2014 R. Ayaz et al. All rights reserved. Optical and Structural Characterization of Nickel Coatings for Solar Collector Receivers Thu, 21 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/ijp/2014/834128/ The development of spectrally selective materials is gaining an increasing role in solar thermal technology. The ideal spectrally selective solar absorber requires high absorbance at the solar spectrum wavelengths and low emittance at the wavelengths of thermal spectrum. Selective coating represents a promising route to improve the receiver efficiency for parabolic trough collectors (PTCs). In this work, we describe an intermediate step in the fabrication of black-chrome based solar absorbers, namely, the fabrication and characterization of nickel coatings on stainless steel substrates. Microstructural characteristics of nickel surfaces are known to favorably affect further black chrome deposition. Moreover, the high reflectivity of nickel in the thermal infrared wavelength region can be advantageously exploited for reducing thermal emission losses. Thus, this report investigates structural features and optical properties of the nickel surfaces, correlating them to coating thickness and deposition process, in the perspective to assess optimal conditions for solar absorber applications. Stefano Pratesi, Elisa Sani, and Maurizio De Lucia Copyright © 2014 Stefano Pratesi et al. All rights reserved.