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Selected Papers from Taiwan Association for Academic Innovation, TAAI 2018

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A special issue of Crystals (ISSN 2073-4352).

Deadline for manuscript submissions: closed (31 December 2018) | Viewed by 42476

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Prof. Dr. Chien-Jung Huang

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Guest Editor

Department of Applied Physics, National University of Kaohsiung, Kaohsiung 81148, Taiwan
Interests: organic solar cell; organic light-emitting diode; nano technology
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Prof. Dr. Kuan Chee

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1. Department of Physics, University of Science and Technology of China, Hefei 230026, China
2. Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China
Interests: metals; polymers; composites; energy storage
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Dr. Yeu-Long Jiang

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Graduate Institute of Optoelectronic Engineering, National Chung Hsing University, Taichung 40227, Taiwan
Interests: silicon thin-film solar cells; silicon heterojuction solar cells; PV systems design, evaluation, and diagonosis
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Special Issue Information

Dear Colleagues,

On behalf of the Taiwan Association for Academic Innovation, we are pleased to welcome you to the 1^st IEEE and International Conference on Science, Engineering, Vocational Education and Novelty (ICSEVEN) 2018, 11–15 April, 2018, Kyoto, Japan. (URL: http://www.taai.tw/icseven/index/ptid/3.html).

Following the first ICSEVEN, held in Guilin, China, and the second in Japan, the conference continuously aims to foster the growth of research in energy engineering science and technology and its benefits to the community at large in the future. We hope that ICSEVEN 2018 will provide a great platform for academic and industry professionals to have fruitful discussions and to exchange new ideas of recent developments and latest advances in the interdisciplinary field. It is our pleasure to announce the supportive participation of leading academics and researchers, in their respective areas of focus, from various countries, not only in, but also beyond Asia. We invite you to participate in this conference by submitting a paper reflecting your current research and to excel in solar energy-related R&D worldwide.

Participants of the conference are cordially invited to contribute original research papers or reviews to this Special Issue of Crystals.

Prof. Dr. Chien-Jung Huang
Prof. Dr. Kuan Chee
Prof. Dr. Yeu-Long Jiang
Guest Editors

Manuscript Submission Information

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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

Solar Cell & module technology
Photovoltaics
Crystallization and wafering of Solar Energy System
New materials for next generation solar cell

Published Papers (11 papers)

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Research

10 pages, 3486 KiB

Open AccessArticle

A Lumped-Parameter Equivalent Circuit Modeling for S-Shaped I–V Kinks of Organic Solar Cells

by Tiankuo Wei, Chuanzhong Xu, Wei Lin, Gongyi Huang and Fei Yu

Crystals 2019, 9(2), 80; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst9020080 - 02 Feb 2019

Cited by 1 | Viewed by 2636

Abstract

We propose an improved lumped-parameter equivalent circuit model to describe S-shaped I–V kinks observed from organic solar cells. Firstly, to predict the S-shaped I–V kinks accurately in both the first and fourth quadrants, a shunt resistor in parallel with extraction diode is added to our previous model. Secondly, based on the Newton–Raphson method, we derive a solution to our improved circuit. Thirdly, our solution is verified by the method of least squares and experiments. Finally, compared with our previous work, the improved circuit has higher accuracy in demonstrating S-shaped I–V kinks in the first and fourth quadrants. Such an improved model is suitable for circuit simulations of organic solar cells. Full article

(This article belongs to the Special Issue Selected Papers from Taiwan Association for Academic Innovation, TAAI 2018)

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14 pages, 8295 KiB

Open AccessArticle

Reactive Mechanism of Cu₂ZnSnSe₄ Thin Films Prepared by Reactive Annealing of the Cu/Zn Metal Layer in a SnSe_x + Se Atmosphere

by Liyong Yao, Jianping Ao, Ming-Jer Jeng, Jinlian Bi, Shoushuai Gao, Guozhong Sun, Qing He, Zhiqiang Zhou, Yi Zhang, Yun Sun and Liann-Be Chang

Crystals 2019, 9(1), 10; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst9010010 - 23 Dec 2018

Cited by 16 | Viewed by 3620

Abstract

Cu₂ZnSnSe₄ (CZTSe) thin films were prepared by a two-step process with the electrodeposition of a Cu/Zn metallic stack precursor followed by a reactive anneal under a Se + Sn containing atmosphere. We investigate the effect of the Se_x and SnSe_x (x = 1,2) partial pressures and annealing temperature on the morphological, structural, and elemental distribution of the CZTSe thin films. Line scanning energy dispersive spectroscopy (EDS) measurements show the presence of a Zn-rich secondary phase at the back-absorber region of the CZTSe thin films processed with higher SnSe_x partial pressure and lower annealing temperatures. The Zn-rich phase can be reduced by lowering the SnSe_x partial pressure and by increasing the annealing temperature. A very thin MoSe₂ film between the CZTSe and Mo interface is confirmed by X-ray diffraction (XRD) and grazing incidence X-ray diffraction (GIXRD) measurements. These measurements indicate a strong dependence of these process variations in secondary phase formation and accumulation. A possible reaction mechanism of CZTSe thin films was presented. In a preliminary optimization of both the SnSe_x partial pressure and the reactive annealing process, a solar cell with 7.26% efficiency has been fabricated. Full article

(This article belongs to the Special Issue Selected Papers from Taiwan Association for Academic Innovation, TAAI 2018)

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12 pages, 4104 KiB

Open AccessArticle

Thickness Study of Er-Doped Magnesium Zinc Oxide Diode by Spray Pyrolysis

by Yu-Ting Hsu, Che-Chi Lee, Wen-How Lan, Kai-Feng Huang, Kuo-Jen Chang, Jia-Ching Lin, Shao-Yi Lee, Wen-Jen Lin, Mu-Chun Wang and Chien-Jung Huang

Crystals 2018, 8(12), 454; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst8120454 - 06 Dec 2018

Cited by 3 | Viewed by 2908

Abstract

Erbium-doped magnesium zinc oxides were prepared through spray pyrolysis deposition at 450 °C with an aqueous solution containing magnesium nitrate, zinc acetate, erbium acetate, and indium nitrate precursors. Diodes with different erbium-doped magnesium zinc oxide thicknesses were fabricated. The effect of erbium-doped magnesium zinc oxide was investigated. The crystalline structure and surface morphology were analyzed using X-ray diffraction and scanning electron microscopy. The films exhibited a zinc oxide structure, with (002), (101), and (102) planes and tiny rods in a mixed hexagonal flakes surface morphology. With the photoluminescence analyses, defect states were identified. The diodes were fabricated via a metallization process in which the top contact was Au and the bottom contact was In. The current–voltage characteristics of these diodes were characterized. The structure resistance increased with the increase in erbium-doped magnesium zinc oxide thickness. With a reverse bias in excess of 8 V, the light spectrum, with two distinct green light emissions at wavelengths of 532 nm and 553 nm, was observed. The light intensity that resulted when using a different operation current of the diodes was investigated. The diode with an erbium-doped magnesium zinc oxide thickness of 230 nm shows high light intensity with an operational current of 80 mA. The emission spectrum with different injection currents for the diodes was characterized and the mechanism is discussed. Full article

(This article belongs to the Special Issue Selected Papers from Taiwan Association for Academic Innovation, TAAI 2018)

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9 pages, 1463 KiB

Open AccessArticle

Investigation of Inverted Perovskite Solar Cells for Viscosity of PEDOT:PSS Solution

by Pao-Hsun Huang, Yeong-Her Wang, Chien-Wu Huang, Wen-Ray Chen and Chien-Jung Huang

Crystals 2018, 8(9), 358; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst8090358 - 06 Sep 2018

Cited by 7 | Viewed by 6545

Abstract

In this paper, we demonstrate that the inverted CH₃NH₃PbI₃ (perovskite) solar cells (PSCs) based on fullerene (C₆₀) as an acceptor is fabricated by applying an improved poly(3,4-ethlyenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) solution as a hole transport layer (HTL). The power conversion efficiency (PCE) of inverted PSCs is increased by 37.5% with stable values of open-circuit voltage (V_OC) and fill factor (FF) because we enhance the viscosity of the PEDOT:PSS solution, indicating the perfect effect on both external quantum efficiency (EQE) and surface grain size. The characteristics of the PEDOT:PSS solution, which is being improved through facile methods of obtaining excellent growth of PEDOT:PSS thin film, have a considerable impact on carrier transport. A series of further processing fabrications, including reliable and feasible heating and stirring techniques before the formation of the PEDOT:PSS thin film via spin-coating, not only evaporate the excess moisture but also obviously increase the conductivity. The raised collection of holes become the reason for the enhanced PCE of 3.0%—therefore, the stable performance of FF and V_OC are attributed to lower series resistance of devices and the high-quality film crystallization of perovskite and organic acceptors, respectively. Full article

(This article belongs to the Special Issue Selected Papers from Taiwan Association for Academic Innovation, TAAI 2018)

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10 pages, 2669 KiB

Open AccessArticle

Highly Efficient Nano-Porous Polysilicon Solar Absorption Films Prepared by Silver-Induced Etching

by Yeu-Long Jiang and Hsiao-Ku Shih

Crystals 2018, 8(9), 354; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst8090354 - 04 Sep 2018

Cited by 1 | Viewed by 4579

Abstract

Nano-porous polysilicon high-temperature resistant solar absorption films were prepared by a thin layer of silver nanoparticles catalytic chemical etching. The polysilicon films with average tiny grain size of approximately 30 nm were obtained by high-temperature 800 °C furnace annealing of hydrogenated amorphous silicon films that were deposited on stainless substrate by plasma-enhanced chemical vapor deposition. The uniformly distributed 19 nm sized silver nanoparticles with 8 nm interspacing deposited on poly-Si film, were controlled by thin 4 nm thickness and very slow deposition rate 0.4 nm/min of thermal evaporation. Small silver nanoparticles with short spacing catalyzes the detouring etching process inducing the nano-porous textured surface with deep threaded pores. The etching follows the trail of the grain boundaries, and takes a highly curved thread like structure. The etching stops after reaching a depth of around 1100 nm, and the rest of the bulk thickness of the film remains mostly unaffected. The structure consists of three crystal orientations (111), (220), and (331) close to the surface. This crystalline nature diminishes gradually in the bulk of the film. High absorbance of 95% was obtained due to efficient light-trapping. Hence, preparation of nano-porous polysilicon films by this simple method can effectively increase solar absorption for the receiver of the solar thermal electricity Stirling Engine. Full article

(This article belongs to the Special Issue Selected Papers from Taiwan Association for Academic Innovation, TAAI 2018)

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5 pages, 1830 KiB

Open AccessArticle

A Screen Method for the Mass-Production of the Small-Size and Side-View LED Package

by Wen-Ray Chen and You-Sheng Luo

Crystals 2018, 8(9), 350; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst8090350 - 31 Aug 2018

Cited by 1 | Viewed by 2282

Abstract

In this study, the small-size and side-view LED packages used in the backlight modules were examined by performing the electrostatic discharge (ESD) process. The high voltages used for the ESD process were 2 kV, 3 kV, and 4 kV. After ESD, the current–voltage curves were scanned from −7 V to 3 V. It was found that the significant leakage currents were in the reverse bias of 4 V~7 V and also in the forward bias of 1 V~2.5 V for ESD-damaged LED chips. However, the phenomenon of a slight increase in current was not found for the non-damaged samples. In our study case, the screening conditions could be set at a bias of −7 V or 2.3 V and the current of 0.1 µA. Full article

(This article belongs to the Special Issue Selected Papers from Taiwan Association for Academic Innovation, TAAI 2018)

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15 pages, 4960 KiB

Open AccessArticle

Investigation of Approaches to Control the Compositions of Zn(Se,OH) Buffers Prepared by Chemical Bath Deposition Process for Cu(In,Ga)Se₂ (CIGS) Solar Cells

by Chia-Hua Huang, Yueh-Lin Jan, Wen-Jie Chuang and Po-Tsung Lu

Crystals 2018, 8(9), 343; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst8090343 - 26 Aug 2018

Cited by 10 | Viewed by 3375

Abstract

We deposited zinc-based films with various ammonia (ammonium hydroxide; NH₄OH) and selenourea concentrations, at the bath temperature of 80 °C, on soda-lime glass substrates using the chemical bath deposition (CBD) process. We analyzed the results using X-ray photoelectron spectroscopy (XPS), which showed binding energies of zinc, selenium, and oxygen. The as-deposited films, containing zinc selenide, zinc oxide, and zinc hydroxide, were also verified. The films prepared in this investigation can be referred to a zinc compound, characterized as Zn(Se,OH). A conformal coverage of the Zn(Se,OH) films, with the smooth surface morphologies, was obtained by optimizing the ammonia or selenourea concentrations in the deposition solutions. The Zn(Se,OH) films had a preferred (111) orientation, corresponding to a cubic crystal structure. The bandgap energies of the as-deposited Zn(Se,OH) films were determined from the optical absorption data, suggesting a dependence of the bandgap energies on the atomic percentages of ZnSe, Zn(OH)₂ and ZnO in the films. The same variation tendency of the compositions and the bandgap energies for the films, deposited with an increment in the ammonia or selenourea concentrations was achieved, attributing to the facilitation of ZnSe formation. These results show that the compositions, and therefore the bandgap energies, can be controlled by the ammonia concentrations, or selenourea concentrations. Full article

(This article belongs to the Special Issue Selected Papers from Taiwan Association for Academic Innovation, TAAI 2018)

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17 pages, 2099 KiB

Open AccessArticle

Multiple Fault Location in a Photovoltaic Array Using Bidirectional Hetero-Associative Memory Network in Micro-Distribution Systems

by Long-Yi Chang, Neng-Sheng Pai, Min-Hung Chou, Jian-Liung Chen, Chao-Lin Kuo and Chia-Hung Lin

Crystals 2018, 8(8), 327; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst8080327 - 15 Aug 2018

Cited by 2 | Viewed by 3025

Abstract

In manual maintenance inspections of large-scaled photovoltaic (PV) or rooftop PV systems, several days are required to survey the entire PV field. To improve reliability and shorten the amount of time involved, this study proposes an electrical examination-based method for locating multiple faults in the PV array. The maximum power point tracking (MPPT) algorithm is used to estimate the maximum power of each PV panel; this is then compared with metering the output power of PV array. Power degradation indexes as input variables are parameterized to quantify the degradation between estimated maximum PV output power and metered PV output power, which can be categorized into normal condition, grounded faults, open-circuit faults, bridged faults, and mismatch faults. Bidirectional hetero-associative memory (BHAM) networks are then used to associate the inputs and locate multiple faults as output variables within the PV array. For a rooftop PV system with two strings, experimental results demonstrate that the proposed model has computational efficiency in learning and detection accuracies for real-time applications, and that its algorithm is easily implemented in a mobile intelligent vehicle. Full article

(This article belongs to the Special Issue Selected Papers from Taiwan Association for Academic Innovation, TAAI 2018)

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17 pages, 9307 KiB

Open AccessArticle

Deposition Technologies of High-Efficiency CIGS Solar Cells: Development of Two-Step and Co-Evaporation Processes

by Chia-Hua Huang, Wen-Jie Chuang, Chun-Ping Lin, Yueh-Lin Jan and Yu-Chiu Shih

Crystals 2018, 8(7), 296; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst8070296 - 18 Jul 2018

Cited by 30 | Viewed by 5811

Abstract

The two-step process including the deposition of the metal precursors followed by heating the metal precursors in a vacuum environment of Se overpressure was employed for the preparation of Cu(In,Ga)Se₂ (CIGS) films. The CIGS films selenized at the relatively high Se flow rate of 25 Å/s exhibited improved surface morphologies. The correlations among the two-step process parameters, film properties, and cell performance were studied. With the given selenization conditions, the efficiency of 12.5% for the fabricated CIGS solar cells was achieved. The features of co-evaporation processes including the single-stage, bi-layer, and three-stage process were discussed. The characteristics of the co-evaporated CIGS solar cells were presented. Not only the surface morphologies but also the grading bandgap structures were crucial to the improvement of the open-circuit voltage of the CIGS solar cells. Efficiencies of over 17% for the co-evaporated CIGS solar cells have been achieved. Furthermore, the critical factors and the mechanisms governing the performance of the CIGS solar cells were addressed. Full article

(This article belongs to the Special Issue Selected Papers from Taiwan Association for Academic Innovation, TAAI 2018)

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10 pages, 11479 KiB

Open AccessArticle

An Improved Organic Solar Cell Lumped-Parameter Equivalent Circuit Model

by Chuanzhong Xu, Fei Yu, Wei Lin and Gongyi Huang

Crystals 2018, 8(7), 277; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst8070277 - 30 Jun 2018

Cited by 8 | Viewed by 3065

Abstract

An improved lumped-parameter equivalent circuit model is proposed to describe S-shaped I–V characteristics of organic solar cells (OSCs). This model originates but differs from Mazhari’s model. As a minor but important modification, a shunt resistance is added to Mazhari’s model to increase the accuracy of simulating the S-shaped kink in the third quadrant. Subsequently, we present a terminal current-voltage equation set and derive an analytical solution to the improved model. Furthermore, we verify the analytical solution to our model by using the least square method and validate our model by using the experimental I–V curves examined from OSCs. Compared with Mazhari’s model, our model has greater accuracy in interpreting the S-shaped kink with linear-like rise in the third quadrant. As a result, our improved model is suitable to explain the S-shaped I–V characteristics of organic solar cells in the whole operational region, especially for the S-shaped kink in the third quadrant. Full article

(This article belongs to the Special Issue Selected Papers from Taiwan Association for Academic Innovation, TAAI 2018)

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8 pages, 2212 KiB

Open AccessArticle

An Analytical Solution to Lumped Parameter Equivalent Circuit Model of Organic Solar Cells

by Gongyi Huang, Fei Yu and Chuanzhong Xu

Crystals 2018, 8(5), 224; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst8050224 - 18 May 2018

Cited by 10 | Viewed by 3599

Abstract

In this paper, an analytical and closed-form solution to the lumped parameter equivalent circuit model of organic solar cells is proposed to complete the simulations of the S-shaped I-V characteristics. Based on the model previously proposed by Mazhari, the set of terminal current and voltage equations describing the three diodes is solved and the effects from the model parameters are illustrated. Our solutions are verified by being compared with the least square method results and experimental data, respectively. Good agreements show that our solution calculation scheme is not only both accurate and efficient, but also valid in the whole operation regime of solar cells, especially for the S-shaped kink on the condition where the terminal voltage is larger than the open circuit voltage. Such an analytical solution can play an important role in the simulations for I-V characteristics of solar cells, fast extractions of the model parameters, and implements into practical photovoltaic device simulators. Full article

(This article belongs to the Special Issue Selected Papers from Taiwan Association for Academic Innovation, TAAI 2018)

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