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Study of poly(3,4-ethylenedioxythiophene) based counter electrodes for efficient dye-sensitized solar cell
Full text linkIn this work the enhancement of dye-sensitized solar cell (DSSC) performance was
studied by developments of new counter electrode (CE) using a combination of three
different materials namely poly(3,4-ethylenedioxythiophene) (PEDOT), carbon-based
material (CBM; graphene oxide (GO), reduced graphene oxide (rGO), nanocrystalline
cellulose (NCC) and multi-walled carbon nanotube (MWCNT)) and titanium dioxide
(TiO2). The counter electrode was prepared by coating indium tin oxide (ITO) glass
with TiO2 followed by deposition of PEDOT incorporated with different CBMs to
produce novel CEs with high performance. Among the CEs PEDOT-NCC/TiO2
exhibited the highest PCE of 2.10 % compared to PEDOT-MWCNT/TiO2 (1.29 %),
PEDOT-rGO/TiO2 (1.10 %) and PEDOT-GO (1.17 %). PEDOT-NCC/TiO2 also
displayed a lower charge transfer resistance (Rct = 2.4 Ω) and higher cathodic peak
current density (Icp = -2.60 mA.cm-2) compared to other CEs due to the synergistic
effect of high conductivity of PEDOT, high surface area and high optical transparency
of NCC and porous structure of TiO2 that provide large surface area. The impact of this
study in photovoltaic technology is to produce an efficient and low cost CE that
capable to substitute a typical CE in DSSC which is platinum that is expensive and rare
metal. The future plan can be pursued by producing a flexible CE to increase its
application in various fields
Development of titanium dioxide based compact layers and light scattering layers for enhanced dye-sensitized solar cell
Full text linkDye-sensitized solar cells (DSSCs) are the third-generation solar cell that
capable of converting solar energy into electrical energy. Titanium dioxide (TiO2)
as a photoanode has faced a lot of drawbacks such as low dye loading capacity,
a small range of light scattering, high recombination effect and low charge
transport ability that subsequently reduces its power conversion efficiency
(PCE). In this work, the enhancement of DSSC performance was studied by the
modification of photoanode, specifically on the fabrication of a new compact layer
(CL) and light scattering layers (LSLs). A dense, compact and homogenous TiO2
CL was optimized and prepared using response surface methodology by central
composite design (RSM/CCD) and heat treatment assisted electrospinning,
respectively. The TiO2 CL was successfully optimized with less than 5% residual
standard error (RSE) and capable of enhancing the PCE up to 76.88% compared
with the bare photoanode (1.73%). This is due to an improved electron lifetime
(τn) and charge collection efficiency (ηc), resulting in a low recombination effect
that leads to a higher PCE. Two LSLs were prepared in this study, namely
polyvinyl alcohol (PVA/TiO2) nanofibers and TiO2 decorated by graphene
quantum dot (TiO2-GQD). The PVA/TiO2 was prepared using electrospinning
while TiO2-GQD was prepared via electrodeposition and drop-casting technique.
Both PVA/TiO2 nanofibers and TiO2-GQD LSLs were successfully optimized
using RSM/CCD with less than 5% RSE. Upon the addition of TiO2-GQD LSL
onto the photoanode, the PCE increased up to 5.01% compared to the
photoanode with PVA/TiO2 nanofibers LSL (4.06%) and bare photoanode
(3.06%). This increment is due to the longer τn, higher ηc, higher dye loading
capacity and higher light reflectance, demonstrating a good light scattering
material. Furthermore, a fully flexible photoanode with TiO2-GQD LSL has
successfully fabricated on indium doped tin oxide/polyethylene naphthalate
(ITO/PEN) flexible substrate via electrodeposition and drop-casting technique.
The fully flexible DSSC device consisting of photoanode with TiO2-GQD LSL showed an enhanced PCE of 5.18% compared to the bare photoanode (2.65%).
The vast enhancement of PCE was due to the increase in the dye loading
capacity (more dye can be adsorbed) and light scattering ability (more light can
be scattered) upon the addition of TiO2-GQD LSL. In a nutshell, the introduction
of CL and LSLs has successfully increased the DSSC performance
Optimization of titanium dioxide decorated by graphene quantum dot as a light scattering layer for enhanced dye-sensitized solar cell performance
Full text linkTitanium dioxide (TiO2) as a photoanode in dye-sensitized solar cells (DSSCs) has some drawbacks that reduce its photovoltaic performances i.e. low dye loading capacity and low light-harvesting efficiency. Therefore, TiO2 decorated by graphene quantum dot (GQD) as a light scatterer has been successfully fabricated via electrodeposition and drop-casting. The response surface methodology/central composite design was successfully utilized to optimize the preparation of photoanode with TiO2-GQD as a light scattering layer (LSL). A reduced quadratic model was successfully designed to predict the power conversion efficiency (PCE) accurately up to 97% with a 3% residual standard error. The TiO2-GQD LSL depicted a cluster of spherical nanoparticles on top of the photoanode that not only enhanced the light scattering effect but also improved the light-harvesting range from visible light to ultraviolet and near-infrared range. The resultant TiO2 nanoparticles with TiO2-GQD LSL showed vast enhancement of PCE up to 66% from 3.06% to 5.01% due to a good synergistic effect
Fully flexible dye-sensitized solar cells photoanode modified with titanium dioxide-graphene quantum dot light scattering layer
Full text linkHerein, we report the preparation of titanium dioxide-graphene quantum dot (TG) as a light scattering layer (LSL) using facile electrodeposition and drop-casting. A fully flexible DSSC device containing TG LSL was capable to generate efficiency of 5.18% which is 95% higher than the bare photoanode (2.65%). Upon the inclusion of TG LSL, the vast enhancement of efficiency was observed which attributed to the improvement in dye loading capacity and light scattering ability. The fully flexible DSSC also depicted higher charge collection efficiency compared to the bare photoanode, indicating enhanced light scattering ability
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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