Special Issue "Selected Papers from Taiwan Association for Academic Innovation, TAAI 2018"

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystalline Materials".

Deadline for manuscript submissions: 31 December 2018

Special Issue Editors

Guest Editor
Prof. Dr. Chien-Jung Huang

Department of Applied Physics, National University of Kaohsiung, Kaohsiung, Taiwan
Website | E-Mail
Interests: organic solar cell; organic light-emitting diode; nano technology
Guest Editor
Prof. Dr. Kuan Chee

Department of Electrical and Electronic Engineering , University of Nottingham Ningbo, China
E-Mail
Guest Editor
Prof. Dr. Yeu-Long Jiang

Department of Electrical Engineering , National Chung Hsing University, Taiwan
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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 1st 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

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

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

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1200 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 (8 papers)

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Research

Open AccessArticle Investigation of Inverted Perovskite Solar Cells for Viscosity of PEDOT:PSS Solution
Crystals 2018, 8(9), 358; https://doi.org/10.3390/cryst8090358
Received: 31 July 2018 / Revised: 16 August 2018 / Accepted: 28 August 2018 / Published: 6 September 2018
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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
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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 (VOC) 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 VOC are attributed to lower series resistance of devices and the high-quality film crystallization of perovskite and organic acceptors, respectively. Full article
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Open AccessArticle Highly Efficient Nano-Porous Polysilicon Solar Absorption Films Prepared by Silver-Induced Etching
Crystals 2018, 8(9), 354; https://doi.org/10.3390/cryst8090354
Received: 1 August 2018 / Revised: 25 August 2018 / Accepted: 2 September 2018 / Published: 4 September 2018
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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
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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
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Open AccessArticle A Screen Method for the Mass-Production of the Small-Size and Side-View LED Package
Crystals 2018, 8(9), 350; https://doi.org/10.3390/cryst8090350
Received: 14 July 2018 / Revised: 9 August 2018 / Accepted: 28 August 2018 / Published: 31 August 2018
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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
[...] Read more.
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
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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
Crystals 2018, 8(9), 343; https://doi.org/10.3390/cryst8090343
Received: 31 July 2018 / Revised: 20 August 2018 / Accepted: 23 August 2018 / Published: 26 August 2018
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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
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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
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Open AccessArticle Multiple Fault Location in a Photovoltaic Array Using Bidirectional Hetero-Associative Memory Network in Micro-Distribution Systems
Crystals 2018, 8(8), 327; https://doi.org/10.3390/cryst8080327
Received: 24 May 2018 / Revised: 12 August 2018 / Accepted: 13 August 2018 / Published: 15 August 2018
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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
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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
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Open AccessArticle Deposition Technologies of High-Efficiency CIGS Solar Cells: Development of Two-Step and Co-Evaporation Processes
Crystals 2018, 8(7), 296; https://doi.org/10.3390/cryst8070296
Received: 31 May 2018 / Revised: 15 July 2018 / Accepted: 16 July 2018 / Published: 18 July 2018
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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
[...] Read more.
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
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Open AccessArticle An Improved Organic Solar Cell Lumped-Parameter Equivalent Circuit Model
Crystals 2018, 8(7), 277; https://doi.org/10.3390/cryst8070277
Received: 26 May 2018 / Revised: 24 June 2018 / Accepted: 27 June 2018 / Published: 30 June 2018
Cited by 1 | PDF Full-text (11479 KB) | HTML Full-text | XML Full-text
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
[...] Read more.
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
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Open AccessArticle An Analytical Solution to Lumped Parameter Equivalent Circuit Model of Organic Solar Cells
Crystals 2018, 8(5), 224; https://doi.org/10.3390/cryst8050224
Received: 21 April 2018 / Revised: 6 May 2018 / Accepted: 17 May 2018 / Published: 18 May 2018
Cited by 2 | PDF Full-text (2212 KB) | HTML Full-text | XML Full-text
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
[...] Read more.
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
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