International Journal of Photoenergy The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Corrigendum to “Enhanced Light Scattering by Preferred Orientation Control of Ga Doped ZnO Films Prepared through MOCVD” Tue, 11 Oct 2016 08:30:35 +0000 Long Giang Bach, Nam Giang Nguyen, Van Thi Thanh Ho, and Lu-Sheng Hong Copyright © 2016 Long Giang Bach et al. All rights reserved. Stable Inverted Low-Bandgap Polymer Solar Cells with Aqueous Solution Processed Low-Temperature ZnO Buffer Layers Sun, 09 Oct 2016 11:48:01 +0000 Efficient inverted low-bandgap polymer solar cells with an aqueous solution processed low-temperature ZnO buffer layer have been investigated. The low-bandgap material PTB-7 is employed so that more solar light can be efficiently harvested, and the aqueous solution processed ZnO electron transport buffer layer is prepared at 150°C so that it can be compatible with the roll-to-roll process. Power conversion efficiency (PCE) of the inverted device reaches 7.12%, which is near the control conventional device. More importantly, the inverted device shows a better stability, keeping more than 90% of its original PCE after being stored for 625 hours, while PCE of the conventional device is only 75% of what it was. In addition, it is found that the ZnO thin film annealed in N2 can obviously increase PCE of the inverted device further to 7.26%. Chunfu Zhang, Shangzheng Pang, Ting Heng, Hailong You, Genquan Han, Gang Lu, Fengqin He, Qubo Jiang, and Jincheng Zhang Copyright © 2016 Chunfu Zhang et al. All rights reserved. Comparison of the Electrical Properties of PERC Approach Applied to Monocrystalline and Multicrystalline Silicon Solar Cells Tue, 04 Oct 2016 07:20:39 +0000 At present, the improvement in performance and the reduction of cost for crystalline silicon solar cells are a key for photovoltaic industry. Passivated emitter and rear cells are the most promising technology for next-generation commercial solar cells. The efficiency gains of passivated emitter and rear cells obtained on monocrystalline silicon wafer and multicrystalline silicon wafer are different. People are puzzled as to how to develop next-generation industrial cells. In this paper, both monocrystalline and multicrystalline silicon solar cells for commercial applications with passivated emitter and rear cells structure were fabricated by using cost-effective process. It was found that passivated emitter and rear cells are more effective for monocrystalline silicon solar cells than for multicrystalline silicon solar cells. This study gives some hints about the industrial-scale mass production of passivated emitter and rear cells process. Enyu Wang, He Wang, and Hong Yang Copyright © 2016 Enyu Wang et al. All rights reserved. Enhancing Performance of SnO2-Based Dye-Sensitized Solar Cells Using ZnO Passivation Layer Mon, 03 Oct 2016 12:14:49 +0000 Although liquid electrolyte based dye-sensitized solar cells (DSCs) have shown higher photovoltaic performance in their class, they still suffer from some practical limitations such as solvent evaporation, leakage, and sealing imperfections. These problems can be circumvented to a certain extent by replacing the liquid electrolytes with quasi-solid-state electrolytes. Even though SnO2 shows high election mobility when compared to the semiconductor material commonly used in DSCs, the cell performance of SnO2-based DSCs is considerably low due to high electron recombination. This recombination effect can be reduced through the use of ultrathin coating layer of ZnO on SnO2 nanoparticles surface. ZnO-based DSCs also showed lower performance due to its amphoteric nature which help dissolve in slightly acidic dye solution. In this study, the effect of the composite SnO2/ZnO system was investigated. SnO2/ZnO composite DSCs showed 100% and 38% increase of efficiency compared to the pure SnO2-based and ZnO-based devices, respectively, with the gel electrolyte consisting of LiI salt. W. M. N. M. B. Wanninayake, K. Premaratne, and R. M. G. R. Rajapakse Copyright © 2016 W. M. N. M. B. Wanninayake et al. All rights reserved. Analysis of the Thermal Stress for Combined Electrode of Soldered Crystalline Silicon Solar Cells under Temperature Field Mon, 26 Sep 2016 13:13:49 +0000 Based on the theory of material mechanics and thermal stress analysis, the stress distribution of combined electrode for crystalline silicon solar module was studied for the first time. The shear stress and normal stress distribution of soldered structure for crystalline silicon solar cells under the thermal field were discussed. And the results show that the stress distribution is not simply linear relationship as some results found. But there is a stress concentration at the edge, which was considered as the true reason that caused microcracks at the edge of soldered solar cells. The conclusions we got in this paper provide a theoretical basis for deceasing the breakage rates of soldered crystalline silicon solar cells and improving the reliability of crystalline silicon solar modules. He Wang, Ao Wang, Hong Yang, and Dengyuan Song Copyright © 2016 He Wang et al. All rights reserved. Performance Characterisation of a Hybrid Flat-Plate Vacuum Insulated Photovoltaic/Thermal Solar Power Module in Subtropical Climate Sun, 25 Sep 2016 13:28:37 +0000 A flat-plate Vacuum Insulated Photovoltaic and Thermal (VIPV/T) system has been thermodynamically simulated and experimentally evaluated to assess the thermal and electrical performance as well as energy conversion efficiencies under a subtropical climate. A simulation model made of specified components is developed in Transient Systems (TRNSYS) environment into which numerical energy balance equations are implemented. The influence of vacuum insulation on the system’s electrical and thermal yields has been evaluated using temperatures, current, voltage, and power flows over daily and annual cycles under local meteorological conditions. The results from an experiment conducted under steady-state conditions in Durban, South Africa, are compared with the simulation based on the actual daily weather data. The VIPV/T has shown improved overall and thermal efficiencies of 9.5% and 16.8%, respectively, while electrical efficiency marginally reduced by 0.02% compared to the conventional PV/T. The simulated annual overall efficiency of 29% (i.e., 18% thermal and 11% electrical) has been realised, in addition to the solar fraction, overall exergy, and primary energy saving efficiencies of 39%, 29%, and 27%, respectively. Andrew Y. A. Oyieke and Freddie L. Inambao Copyright © 2016 Andrew Y. A. Oyieke and Freddie L. Inambao. All rights reserved. Effect of Plasma, RF, and RIE Treatments on Properties of Double-Sided High Voltage Solar Cells with Vertically Aligned p-n Junctions Thu, 22 Sep 2016 14:15:28 +0000 Si-based solar cells with vertically aligned p-n junctions operating at high voltage were designed and fabricated. The plasma treatments and antireflection coating deposition on the working surfaces of both single- and multijunction cells were made using the special holders. It was shown that additional treatment of solar cells in argon plasma prior to hydrogen plasma treatment and deposition of diamond-like carbon antireflection films led to the improvement of the cell efficiency by up to 60%. Radio frequency waves support plasma generation and improve photoelectric conversion mainly due to reduction of internal stresses at the interfaces. Application of reactive ion etching technique removes the broken layer, reduces elastic strain in the wafer, decreases recombination of charge carriers in the bulk, and provides cell efficiency increase by up to ten times. Mykola O. Semenenko, Mykhailo G. Dusheiko, Sergiy V. Mamykin, Valeriy O. Ganus, Mykhailo V. Kirichenko, Roman V. Zaitsev, Mykola M. Kharchenko, and N. I. Klyui Copyright © 2016 Mykola O. Semenenko et al. All rights reserved. Modeling and Analysis of New Multilevel Inverter for Solar Photovoltaic Power Plant Wed, 21 Sep 2016 14:09:20 +0000 Solar photovoltaic (PV) power plant is an effective way to utilize the renewable energy sources. EMI is one of the major concerns in PV power plant. Typically, the multilevel inverters are used in high voltage PV power plant. However, the conventional multilevel inverters require more semiconductors, which complicate the circuit structure and control algorithm. In this paper, a novel five-level inverter is introduced for the high voltage PV power plant applications. The model of the inverter is analyzed. With the redundant switching states, a new modulation strategy is proposed to reduce the common-mode voltage and EMI. The proposed approach is able to eliminate the common-mode voltage; meanwhile it has the capability of balancing the capacitor voltages. The cosimulation tests with the Matlab/Simulink and S-function are carried out. The results verify the effectiveness of the proposed method. Xiaoqiang Guo, Ran He, and Mehdi Narimani Copyright © 2016 Xiaoqiang Guo et al. All rights reserved. Highly Reflective Dielectric Back Reflector for Improved Efficiency of Tandem Thin-Film Solar Cells Wed, 21 Sep 2016 13:46:54 +0000 We report on the prototyping and development of a highly reflective dielectric back reflector for application in thin-film solar cells. The back reflector is fabricated by Snow Globe Coating (SGC), an innovative, simple, and cheap process to deposit a uniform layer of TiO2 particles which shows remarkably high reflectance over a broad spectrum (average reflectance of 99% from 500 nm to 1100 nm). We apply the highly reflective back reflector to tandem thin-film silicon solar cells and compare its performance with conventional ZnO:Al/Ag reflector. By using SGC back reflector, an enhancement of 0.5 mA/cm2 in external quantum efficiency of the bottom solar cell and an absolute value of 0.2% enhancement in overall power conversion efficiency are achieved. We also show that the increase in power conversion efficiency is due to the reduction of parasitic absorption at the back contact; that is, the use of the dielectric reflector avoids plasmonic losses at the reference ZnO:Al/Ag back reflector. The Snow Globe Coating process is compatible with other types of solar cells such as crystalline silicon, III–V, and organic photovoltaics. Due to its cost effectiveness, stability, and excellent reflectivity above a wavelength of 400 nm, it has high potential to be applied in industry. Chog Barugkin, Ulrich W. Paetzold, Kylie R. Catchpole, Angelika Basch, and Reinhard Carius Copyright © 2016 Chog Barugkin et al. All rights reserved. Photovoltaic Materials and Devices 2016 Sun, 18 Sep 2016 11:00:19 +0000 Bhushan Sopori, Prakash Basnyat, and Vishal Mehta Copyright © 2016 Bhushan Sopori et al. All rights reserved. Sliding Mode Real-Time Control of Photovoltaic Systems Using Neural Estimators Wed, 14 Sep 2016 13:48:43 +0000 The maximum power point tracking (MPPT) problem has attracted the attention of many researchers, because it is convenient to obtain the maximum power of a photovoltaic module regardless of the weather conditions and the load. In this paper, a novel control for a boost DC/DC converter has been introduced. It is based on a sliding mode controller (SMC) that takes a current signal as reference instead of a voltage, which is generated by a neuronal reference current generator. That reference current indicates the current () at the maximum power point (MPP) for given weather conditions. In order to test the designed control system, a photovoltaic module model based on a second artificial neuronal network (ANN) has been obtained from experimental data gathered during 18 months in the Faculty of Engineering Vitoria-Gasteiz (Spain). We have analyzed the performance of such model and we found that it is very accurate (MSE = 0.062 A and = 0.991 with test dataset). We also have tested the performance of the overall SMC design with both simulated and real tests, concluding that it guarantees that the power in the output of the converter is very close to the power of the photovoltaic module output. J. A. Ramos-Hernanz, O. Barambones, J. M. Lopez-Guede, I. Zamora, P. Eguia, and M. Farhat Copyright © 2016 J. A. Ramos-Hernanz et al. All rights reserved. Ag-Doped TiO2 Nanotube Arrays Composite Film as a Photoanode for Enhancing the Photoelectric Conversion Efficiency in DSSCs Thu, 08 Sep 2016 06:32:32 +0000 A Ag-doped double-layer composite film with TiO2 nanoparticles (P25) as the underlayer and TiO2 nanotube (TNT) arrays with the Ag-doped nanoparticles as the overlayer was fabricated as the photoanode in dye-sensitized solar cells (DSSCs). Five different concentrations of Ag-doped TNT arrays photoelectrode were compared with the pure TNT arrays composite photoelectrode. It is found that the photoelectric conversion efficiency of the TNT arrays composite photoanode is gradually improved from 3.00% of the pure TNT arrays composite photoanode to 6.12% of the Ag-doped TNT arrays photoanode with the increasing of the doping concentration, reaching up to the maximum in the 0.04 mol/L AgNO3 solution, and then slightly decreased to 5.43% after continuing to increase the doping concentration. The reason is mainly that the cluster structure of the Ag nanoparticles with large surface area contributes to dye adsorption and the Surface Plasmon Resonance Effect of the Ag nanoparticles improved the photocatalytic ability of the TNT arrays film. Jinghua Hu, Jiejie Cheng, Shengqiang Tong, Yingping Yang, Mengwei Chen, and Shiwu Hu Copyright © 2016 Jinghua Hu et al. All rights reserved. High Quality GaAs Epilayers Grown on Si Substrate Using 100 nm Ge Buffer Layer Wed, 07 Sep 2016 10:09:25 +0000 We present high quality GaAs epilayers that grow on virtual substrate with 100 nm Ge buffer layers. The thin Ge buffer layers were modulated by hydrogen flow rate from 60 to 90 sccm to improve crystal quality by electron cyclotron resonance chemical vapor deposition (ECR-CVD) at low growth temperature (180°C). The GaAs and Ge epilayers quality was verified by X-ray diffraction (XRD) and spectroscopy ellipsometry (SE). The full width at half maximum (FWHM) of the Ge and GaAs epilayers in XRD is 406 arcsec and 220 arcsec, respectively. In addition, the GaAs/Ge/Si interface is observed by transmission electron microscopy (TEM) to demonstrate the epitaxial growth. The defects at GaAs/Ge interface are localized within a few nanometers. It is clearly showed that the dislocation is well suppressed. The quality of the Ge buffer layer is the key of III–V/Si tandem cell. Therefore, the high quality GaAs epilayers that grow on virtual substrate with 100 nm Ge buffer layers is suitable to develop the low cost and high efficiency III–V/Si tandem solar cells. Wei-Cheng Kuo, Hung-Chi Hsieh, Wu Chih-Hung, Huang Wen-Hsiang, Chien-Chieh Lee, and Jenq-Yang Chang Copyright © 2016 Wei-Cheng Kuo et al. All rights reserved. Synthesis and Characterization of Graphene Oxide-Modified Bi2WO6 and Its Use as Photocatalyst Mon, 05 Sep 2016 14:09:16 +0000 A Bi2WO6 photocatalyst modified with graphene was synthesized in a two-step template-free hydrothermal process. The prepared samples were characterized to explore their properties. The photocatalytic activities of the prepared samples were investigated by degrading dye model, Rhodamine B (RhB), under visible light irradiation. This showed that the modified Bi2WO6 photocatalyst with 1.2 wt% of graphene greatly improved photocatalytic activity during the degradation of dye pollutants, compared to pure Bi2WO6. The enhancement can be interpreted as the integrated effects of ultrahigh charge carriers’ mobility and high adsorption of RhB on graphene. Additionally, effects including catalysts dosage amount, pH of RhB solution, and temperature of reactor on the photocatalytically degrading RhB were also studied and discussed. Xiaoyue Hu, Xiangchao Meng, and Zisheng Zhang Copyright © 2016 Xiaoyue Hu et al. All rights reserved. Photocatalytic Activity and Optical Properties of Blue Persistent Phosphors under UV and Solar Irradiation Thu, 01 Sep 2016 09:28:41 +0000 Blue phosphorescent strontium aluminosilicate powders were prepared by combustion synthesis route and a postannealing treatments at different temperatures. X-ray diffraction analysis showed that phosphors are composed of two main hexagonal phases: SrAl2O4 and Sr3Al32O51. The morphology of the phosphors changed from micrograins (1000°C) to a mixture of bars and hexagons (1200°C) and finally to only hexagons (1300°C) as the annealing temperature is increased. Photoluminescence spectra showed a strong blue-green phosphorescent emission centered at  nm, which is associated with transition of the Eu2+. The sample annealed at 1200°C presents the highest luminance value (40 Cd/m2) with CIE coordinates (0.1589, 0.1972). Also, the photocatalytic degradation of methylene blue (MB) under UV light (at 365 nm) was monitored. Samples annealed at 1000°C and 1300°C presented the highest percentage of degradation (32% and 38.5%, resp.) after 360 min. In the case of photocatalytic activity under solar irradiation, the samples annealed at 1000°C, 1150°C, and 1200°C produced total degradation of MB after only 300 min. Hence, the results obtained with solar photocatalysis suggest that our powders could be useful for water cleaning in water treatment plants. C. R. García, L. A. Diaz-Torres, J. Oliva, M. T. Romero, and P. Salas Copyright © 2016 C. R. García et al. All rights reserved. A Simple Technique for Sustaining Solar Energy Production in Active Convective Coastal Regions Tue, 30 Aug 2016 13:44:25 +0000 The climatic factors in the coastal areas are cogent in planning a stable and functional solar farm. 3D simulations relating the surface temperature, sunshine hour, and solar irradiance were adopted to see the effect of minute changes of other meteorological parameters on solar irradiance. This enabled the day-to-day solar radiation monitoring with the primary objective to examine the best technique for maximum power generation via solar option in coastal locations. The month of January had the highest turbulent features, showing the influence of weather and the poorest solar radiance due to low sunshine hour. Twenty-year weather parameters in the research area were simulated to express the systematic influence of weather of PV performance. A theoretical solar farm was illustrated to generate stable power supply with emphasis on the longevity of the PV module proposed by introducing an electronic concentrator pillar (CP). The pictorial and operational model of the solar farm was adequately explained. Moses E. Emetere, Marvel L. Akinyemi, and Etimbuk B. Edeghe Copyright © 2016 Moses E. Emetere et al. All rights reserved. Effect of Codoping Cl Anion and 5-AVA Cation on Performance of Large-Area Perovskite Solar Cells with Double-Mesoporous Layers Tue, 30 Aug 2016 08:57:39 +0000 For the perovskite solar cells (PSCs), the performance of the PSCs has become the focus of the research by improving the quality of the perovskite absorption layer. So far, the performance of the large-area PSCs is lower than that of small-area PSCs. In the paper, the experiments were designed to improve the photovoltaic performance of the large-area PSCs by improved processing technique. Here we investigated the optoelectronic properties of the prototypical CH3NH3PbI3 (MAPbI3) further modulated by introducing other extrinsic ions (specifically codoped Cl− and 5-AVA+). Moreover, we used inorganic electron extraction layer to achieve very rapid photogenerated carrier extraction eliminating local structural defects over large areas. Ultimately, we fabricated a best-performing perovskite solar cell based on codoping Cl anion and 5-AVA cation which uses a double layer of mesoporous TiO2 and ZrO2 as a scaffold infiltrated with perovskite and does not require a hole-conducting layer. The experiment results indicated that an average efficiency of double-mesoporous layer-based devices with codoping Cl anion and 5-AVA cation was obtained with exceeding 50% enhancement, compared to that of pure single-mesoporous layer-based device. Yaxian Pei, Xiaoping Zou, Yingxiang Guan, and Gongqing Teng Copyright © 2016 Yaxian Pei et al. All rights reserved. Wide-Range Enhancement of Spectral Response by Highly Conductive and Transparent μc-SiOx:H Doped Layers in μc-Si:H and a-Si:H/μc-Si:H Thin-Film Solar Cells Wed, 24 Aug 2016 09:58:28 +0000 The enhancement of optical absorption of silicon thin-film solar cells by the p- and n-type μc-SiOx:H as doped and functional layers was presented. The effects of deposition conditions and oxygen content on optical, electrical, and structural properties of μc-SiOx:H films were also discussed. Regarding the doped μc-SiOx:H films, the wide optical band gap () of 2.33 eV while maintaining a high conductivity of 0.2 S/cm could be obtained with oxygen incorporation of 20 at.%. Compared to the conventional μc-Si:H(p) as window layer in μc-Si:H single-junction solar cells, the application of μc-SiOx:H(p) increased the and led to a significant enhancement in the short-wavelength spectral response. Meanwhile, the employment of μc-SiOx:H(n) instead of conventional ITO as back reflecting layer (BRL) enhanced the external quantum efficiency (EQE) of μc-Si:H single-junction cell in the long-wavelength region, leading to a relative efficiency gain of 10%. Compared to the reference cell, the optimized a-Si:H/μc-Si:H tandem cell by applying p- and n-type μc-SiOx:H films achieved a of 1.37 V, of 10.55 mA/cm2, FF of 73.67%, and efficiency of 10.51%, which was a relative enhancement of 16%. Pei-Ling Chen, Po-Wei Chen, Min-Wen Hsiao, Cheng-Hang Hsu, and Chuang-Chuang Tsai Copyright © 2016 Pei-Ling Chen et al. All rights reserved. Heterogeneous Photochemistry: Solar Energy Conversion and Environmental Remediation Sun, 21 Aug 2016 08:24:50 +0000 Daniele Dondi, Sandra Babić, Irene Michael, Giovanni Palmisano, and Andrea Speltini Copyright © 2016 Daniele Dondi et al. All rights reserved. Preparation of a Textile-Based Dye-Sensitized Solar Cell Sun, 14 Aug 2016 07:14:15 +0000 Solar energy conversion is an object of continuous research, focusing on improving the energy efficiency as well as the structure of photovoltaic cells. With efficiencies continuously increasing, state-of-the-art PV cells offer a good solution to harvest solar energy. However, they are still lacking the flexibility and conformability to be integrated into common objects or clothing. Moreover, many sun-exposed surface areas are textile-based such as garments, tents, truck coverings, boat sails, and home or outdoor textiles. Here, we present a new textile-based dye-sensitized solar cell (DSC) which takes advantage from the properties inherent to fabrics: flexibility, low weight, and mechanical robustness. Due to the necessary thermostability during manufacturing, our DSC design is based on heat-resistant glass-fiber fabrics. After applying all needed layers, the overall structure was covered by a transparent and simultaneously conductive protective film. The light and still flexible large-area devices (up to 6 cm2 per individual unit) are working with efficiencies up to 1.8% at 1/5 of the sun. Stability tests assure no loss of photovoltaic activity over a period of at least seven weeks. Therefore, our technology has paved the way for a new generation of flexible photovoltaic devices, which can be used for the generation of power in the mentioned applications as well as in modern textile architecture. Klaus Opwis, Jochen Stefan Gutmann, Ana Rosa Lagunas Alonso, Maria Jesus Rodriguez Henche, Mikel Ezquer Mayo, Fanny Breuil, Enrico Leonardi, and Luca Sorbello Copyright © 2016 Klaus Opwis et al. All rights reserved. Study of Transition Region of p-Type SiO:H as Window Layer in a-Si:H/a-SiGe:H Multijunction Solar Cells Mon, 08 Aug 2016 16:27:11 +0000 We have studied the p-type hydrogenated silicon oxide (:H) films prepared in the amorphous-to-microcrystalline transition region as a window layer in a-Si:H/a-:H multijunction solar cells. By increasing the -to- flow ratio () from 10 to 167, the :H(p) films remained amorphous and exhibited an increased hydrogen content from 10.2% to 12.2%. Compared to the amorphous :H(p) film prepared at low , the :H(p) film deposited at of 167 exhibited a higher bandgap of 2.04 eV and a higher conductivity of 1.15 × 10−5 S/cm. With the employment of :H(p) films prepared by increasing from 10 to 167 in a-Si:H single-junction cell, the FF improved from 65% to 70% and the efficiency increased from 7.4% to 8.7%, owing to the enhanced optoelectrical properties of :H(p) and the improved p/i interface. However, the cell that employed :H(p) film with over 175 degraded the p/i interface and degraded the cell performance, which were arising from the onset of crystallization in the window layer. Compared to the cell using standard a-:H(p), the a-Si:H/a-:H tandem cells employing :H(p) deposited with of 167 showed an improved efficiency from 9.3% to 10.3%, with of 1.60 V, of 9.3 mA/cm2, and FF of 68.9%. Pei-Ling Chen, Po-Wei Chen, and Chuang-Chuang Tsai Copyright © 2016 Pei-Ling Chen et al. All rights reserved. A Population Classification Evolution Algorithm for the Parameter Extraction of Solar Cell Models Mon, 08 Aug 2016 13:19:29 +0000 To quickly and precisely extract the parameters for solar cell models, inspired by simplified bird mating optimizer (SBMO), a new optimization technology referred to as population classification evolution (PCE) is proposed. PCE divides the population into two groups, elite and ordinary, to reach a better compromise between exploitation and exploration. For the evolution of elite individuals, we adopt the idea of parthenogenesis in nature to afford a fast exploitation. For the evolution of ordinary individuals, we adopt an effective differential evolution strategy and a random movement of small probability is added to strengthen the ability to jump out of a local optimum, which affords a fast exploration. The proposed PCE is first estimated on 13 classic benchmark functions. The experimental results demonstrate that PCE yields the best results on 11 functions by comparing it with six evolutional algorithms. Then, PCE is applied to extract the parameters for solar cell models, that is, the single diode and the double diode. The experimental analyses demonstrate that the proposed PCE is superior when comparing it with other optimization algorithms for parameter identification. Moreover, PCE is tested using three different sources of data with good accuracy. Yiqun Zhang, Peijie Lin, Zhicong Chen, and Shuying Cheng Copyright © 2016 Yiqun Zhang et al. All rights reserved. Carrier Formation Dynamics in Prototypical Organic Solar Cells as Investigated by Transient Absorption Spectroscopy Mon, 08 Aug 2016 13:19:18 +0000 Subpicosecond transient absorption spectroscopy is a powerful tool used to clarify the exciton and carrier dynamics within the organic solar cells (OSCs). In this review article, we introduce a method to determine the absolute numbers of the excitons and carriers against delay time (t) only from the photoinduced absorption (PIA) and electrochemically induced absorption (EIA) spectra. Application of this method to rr-P3HT-, PTB7-, and SMDPPEH-based OSCs revealed common aspects of the carrier formation dynamics. First, the temporal evolution of the numbers of the excitons and carriers indicates that the late decay component of exciton does not contribute to the carrier formation process. This is probably because the late component has not enough excess energy to separate into the electron and hole across the donor/acceptor (D/A) interface. Secondly, the spectroscopy revealed that the exciton-to-carrier conversion process is insensitive to temperature. This observation, together with the fast carrier formation time in OSCs, is consistent with the hot exciton picture. Yutaka Moritomo, Kouhei Yonezawa, and Takeshi Yasuda Copyright © 2016 Yutaka Moritomo et al. All rights reserved. The Influence of Heating Time and Temperature on the Properties of CIGSSe Solar Cells Sun, 07 Aug 2016 12:56:24 +0000 Nonencapsulated CIGSSe solar cells, with a silver grid, were exposed to different temperatures for various periods in order to measure the effect of the heat exposure in CIGSSe modules. The heat treatment time and temperature were varied during the experiments, which were executed at atmospheric conditions. In all the cases, after reaching a temperature of about 300°C, the IV measurement showed a reduction of 2-3% in terms of and . This is confirmed, respectively, by Raman and EQE measurements as well. The efficiency drop was −7%, −29%, and −48%, respectively, for 30 seconds, 300 seconds, and 600 seconds of exposure time. With temperatures larger than 225°C, the series resistance starts to increase exponentially and a secondary barrier becomes visible in the IV curve. This barrier prevents the extraction of electrons and consequently reducing the solar cells efficiency. Lock-in thermography demonstrated the formation of shunts on the mechanical scribes only for 300 and 600 seconds exposure times. The shunt resistance reduction is in the range of 5% for all time periods. Marco Giacomo Flammini, Nicola Debernardi, Maxime Le Ster, Brendan Dunne, Johan Bosman, and Mirjam Theelen Copyright © 2016 Marco Giacomo Flammini et al. All rights reserved. Accelerated Life Test for Photovoltaic Cells Using Concentrated Light Sun, 07 Aug 2016 08:24:56 +0000 This paper presents a new method developed to significantly reduce the necessary time for the ageing tests for different types of photovoltaic cells. Two ageing factors have been applied to the photovoltaic cells: the concentrated light and the temperature. The maximum power of the photovoltaic cells was monitored during the ageing process. The electrical dc and ac parameters of the photovoltaic cells were measured and analyzed at 1 sun irradiance, before and after the test stress. During the test, two photovoltaic cells are kept at maximum power point and the other two are kept at open circuit voltage point. The method is validated through the results obtained for the monocrystalline silicon solar cell. Daniel Tudor Cotfas, Petru Adrian Cotfas, Dan Ion Floroian, and Laura Floroian Copyright © 2016 Daniel Tudor Cotfas et al. All rights reserved. Adhesion Improvement and Characterization of Magnetron Sputter Deposited Bilayer Molybdenum Thin Films for Rear Contact Application in CIGS Solar Cells Tue, 02 Aug 2016 11:18:28 +0000 Molybdenum (Mo) thin films are widely used as rear electrodes in copper indium gallium diselenide (CIGS) solar cells. The challenge in Mo deposition by magnetron sputtering lies in simultaneously achieving good adhesion to the substrates while retaining the electrical and optical properties. Bilayer Mo films, comprising five different thickness ratios of a high pressure (HP) deposited bottom layer and a low pressure (LP) deposited top layer, were deposited on 40 cm × 30 cm soda-lime glass substrates by DC magnetron sputtering. We focus on understanding the effects of the individual layer properties on the resulting bilayer Mo films, such as microstructure, surface morphology, and surface oxidation. We show that the thickness of the bottom HP Mo layer plays a major role in determining the micromechanical and physical properties of the bilayer Mo stack. Our studies reveal that a thicker HP Mo bottom layer not only improves the adhesion of the bilayer Mo, but also helps to improve the film crystallinity along the preferred [] direction. However, the surface roughness and the porosity of the bilayer Mo films are found to increase with increasing bottom layer thickness, which leads to lower optical reflectance and a higher probability for oxidation at the Mo surface. Weimin Li, Xia Yan, Armin G. Aberle, and Selvaraj Venkataraj Copyright © 2016 Weimin Li et al. All rights reserved. Sorbents Coupled to Solar Light TiO2-Based Photocatalysts for Olive Mill Wastewater Treatment Sun, 31 Jul 2016 11:56:37 +0000 The aim of this work was to couple physical-chemical approaches with photocatalysis to reduce by a simple, inexpensive way the organic load of olive mill wastewater (OMW), mandatorily prior to the final discharge. Before irradiation, different sorbents were tested to remove part of the organic fraction, monitored by measuring chemical oxygen demand (COD) and polyphenols (PP). Different low-cost, safe materials were tested, that is, Y zeolite (ZY), montmorillonite, and sepiolite. Considerable decrease of organic load was obtained, with the highest abatement (40%) provided by ZY (10 g L−1 in 1 : 10 OMW). Use of the three sorbents, in particular ZY, was convenient compared to commercial activated carbons. UV light photocatalytic tests, performed using P25 TiO2 on ZY-treated OMW, yielded quantitative remediation (ca. 90%). Also solar light provided significative results, PP being lowered by 74% and COD by 56%. Sol-gel anatase TiO2 and N-doped anatase TiO2 were also tested, obtaining good results, around 80% PP and 40% COD. Finally, an integrated approach was experimented by ZY-supported anatase TiO2 (TiO2@ZY). This photoreactive sorbent allowed one-pot treatment of OMW significative abatements of PP (77%) and COD (39%) with only 1 g L−1 material, under solar light. Andrea Speltini, Federica Maraschi, Michela Sturini, Valentina Caratto, Maurizio Ferretti, and Antonella Profumo Copyright © 2016 Andrea Speltini et al. All rights reserved. Evaluation of Hydrocalumite-Like Compounds as Catalyst Precursors in the Photodegradation of 2,4-Dichlorophenoxyacetic Acid Sun, 31 Jul 2016 07:20:30 +0000 Three hydrocalumite-like compounds in a Ca/Al ratio of 2 containing nitrate and acetate anions in the interlaminar region were prepared by a simple, economic, and environmentally friendly method. The solids were characterized by X-ray powder diffraction (XRD), thermogravimetric (TG) analysis, nitrogen adsorption-desorption at −196°C, scanning electron microscopy (SEM), infrared spectroscopy (FTIR), and UV-Vis Diffuse Reflectance Spectroscopy (DRS). The catalytic activity of the calcined solids at 700°C was tested in the photodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) where 57% degradation of 2,4-D (40 ppm) and a mineralization percentage of 60% were accomplished within 150 minutes. The photocatalytic properties were attributed to mayenite hydration, since the oxide ions in the cages are capable of reacting with water to form hydroxide anions capable of breaking down the 2,4-D molecules. Manuel Sánchez-Cantú, Clara Barcelos-Santiago, Claudia M. Gomez, Esthela Ramos-Ramírez, Ma. de Lourdes Ruiz Peralta, Nancy Tepale, Valeria J. González-Coronel, A. Mantilla, and Francisco Tzompantzi Copyright © 2016 Manuel Sánchez-Cantú et al. All rights reserved. Heuristic Storage System Sizing for Optimal Operation of Electric Vehicles Powered by Photovoltaic Charging Station Thu, 28 Jul 2016 13:25:13 +0000 This paper discusses the utilisation of PV systems for electric vehicles charging for transportation requirements of smart cities. The gap between PV power output and vehicles charging demand is highly variable. Therefore, there is a need for additional support from a public distribution grid or a storage device in order to handle the residual power. Long term measurement data retrieved from a charging station for 15 vehicles equipped with a PV system were used in the research. Low and high irradiation seasons influenced the PV output. The charging demand of electric vehicles varied over the course of a year and was correlated to weather conditions. Therefore, the sizing and performance of a supportive storage device should be evaluated in a statistical manner using long period observations. Erik Blasius, Erik Federau, Przemyslaw Janik, and Zbigniew Leonowicz Copyright © 2016 Erik Blasius et al. All rights reserved. Multicore PSO Operation for Maximum Power Point Tracking of a Distributed Photovoltaic System under Partially Shading Condition Mon, 25 Jul 2016 11:57:02 +0000 This paper identifies the partial shading problem of a PV module using the one-diode model and simulating the characteristics exhibiting multiple-peak power output condition that is similar to a PV array. A modified particle swarm optimization (PSO) algorithm based on the suggested search-agent deployment, retracking condition, and multicore operation is proposed in order to continuously locate the global maximum power point for the PV system. Partial shading simulation results for up to 16 modules in series/parallel formats are presented. A distributed PV system consisting of up to 8 a-silicon thin film PV panels and also having a dedicated DC/DC buck converter on each of the modules is tested. The converter reaches its steady state voltage output in 10 ms. However for MPPT operation, voltage, and current measurement interval is set to 20 ms to avoid unnecessary noise from the entire electric circuit. Based on the simulation and experiment results, each core of the proposed PSO operation should control no more than 4 PV modules in order to have the maximum tracking accuracy and minimum overall tracking time. Tracking for the global maximum power point of a distributed PV system under various partial shading conditions can be done within 1.3 seconds. Ru-Min Chao, Ahmad Nasirudin, I-Kai Wang, and Po-Lung Chen Copyright © 2016 Ru-Min Chao et al. All rights reserved.