Transparent Conducting Oxide Glass Substrates Research Articles

Transparent 3 nm-thick MoS2 counter electrodes for bifacial dye-sensitized solar cells

Molybdenum disulfide (MoS2) counter electrode (CE) is considered one of the most viable alternatives to Pt CE in dye-sensitized solar cells (DSSCs) owing to its abundance, low cost, and superior electrocatalytic activity. However, mostly, MoS2 CEs for DSSCs are prepared by conventional chemical reactions and annealing at a high temperature. By these conventional processes, deposition of sufficiently thin and transparent MoS2 layers is challenging; therefore, bifacial DSSCs employing transparent MoS2 CEs have not been studied. Here, we report transparent few-nanometer-thick MoS2 CEs prepared by atomic layer deposition at a relatively low temperature (98°C) for bifacial DSSC applications. MoS2 nanofilms with precisely controlled thicknesses of 3–16nm are conformally coated on transparent conducting oxide glass substrates. With increase in the MoS2 nanofilm thickness, the MoS2 CE electrocatalytic activity for the iodide/triiodide redox couple enhances, but its transparency decreases. Notably, the application of a thinner MoS2 nanofilm in a bifacial DSSC leads to lower conversion efficiency under front-illumination, but higher conversion efficiency under back-illumination. In particular, only the 3nm-thick MoS2 nanofilm shows reasonable photovoltaic performances under both front- and back-illumination conditions.

Photodetector Characterization Based on DSSC (Dye-Sensitized Solar Cell)

A photodetector performance as a light sensor based on the design and material of DSSC (Dye-Sensitized Solar Cell) has been characterized. Oxide Semiconductor nanoparticle of TiO2 and extracted natural dye are used to absorb and convert incident photon to electric energy using a sandwich structure of 1.5 x 1.5 cm2 active area. The sensor materials were used include TCO (Transparent Conductive Oxide) glass as substrate, electrolyte solution and carbon. Method of TiO2 deposition to the TCO glass substrate is spin coating and firing at 1,500 rpm and 450 °C, respectively. Natural dye was extracted from green algae by a different variation of solution concentration according to the ratio of mass and volume. The chlorophyll absorbance was investigated by spectrophotometer at a wavelength of 300-800 nm. SEM (Scanning Electron Microscope) is used to observe TiO2-coated TCO glass morphology. Fabricated sensors are characterized according to the electrical parameters of voltage and current towards light illuminance from the light source. This natural dye-based optical photodetector performance has been analysed to obtain linearity, sensitivity, uncertainty error, and other electrical transient response characteristics. The result of extracted chlorophyte absorbance shows a wavelength peak at 580 to 680 nm with different intensity; it indicates the visible light absorbance spectra occurred. Sensor measurement using light illumination up to 30,000 lux produces the highest rated voltage of 626.4 mV and current 78,7 (µA) at the ratio of 6:5 (m:v) solution. This sensor has a voltage sensitivity of 1,0875 mV/10lux and the current sensitivity of 0.0024 µA/lux. The voltage and current uncertainty error are 0.36% and 0.481%, respectively.

Extended Study on Electrophoretic Deposition Process of Inorganic Octahedral Metal Clusters: Advanced Multifunctional Transparent Nanocomposite Thin Films

Abstract This review paper summarizes our very recent works on the synthesis of multifunctional transparent nanocomposite thin films or coatings based on metal atom clusters by an electrophoretic deposition (EPD) process. Eight different octahedral atom clusters with niobium, molybdenum or tantalum as metallic cores were used to prepare highly transparent thin films in the visible. Green, yellow, orange, red and brown colored films were successfully fabricated by coating on a transparent conductive oxide glass substrate. Transparent nanocomposite films with prominent luminescent properties were obtained by using Mo6 clusters whereas ultra-violet (UV) and near infrared (NIR) filters were realized by using Nb6 or Ta6 clusters. The EPD process appears to be a new strategy to fabricate highly transparent, homogeneous and colored nanocomposite thin films and coatings for smart windows and solar technologies in a very short time (<90 s).

Influence of the type of conducting glass substrate on the properties of electrodeposited CdS and CdTe thin films

Owing to the greater efficiency in energy conversion by absorbing energy in a wider range of the solar spectrum, thin film CdS/CdTe solar cells have been popularized as a prominent application of photovoltaics and the technique of electrodeposition (ED) is an ideal method available for producing both CdS and CdTe materials upon its outrivaled simplicity, low cost, scalability and manufacturability. Typically the quality of these deposited thin films depends on several growth parameters and amid them, the type of conducting glass substrate plays a crucial role. This study is focused on the influence of conducting glass substrate on the properties of electrodeposited CdS and CdTe thin films. Two types of glass substrates coated with different transparent conducting oxide (TCO) layers namely; fluorine-doped tin oxide (FTO) and indium tin oxide (ITO) having different sheet resistances (FTO: 7 and 13 Ω/sq and ITO: 7 and 15 Ω/sq) were considered. CdS and CdTe materials were electrodeposited respectively on each of these types of TCO layers using a three electrode electrolytic system under a consistent set of growth parameters which has been pre-optimized with respect to FTO having sheet resistance of 7 Ω/sq. The deposited CdS and CdTe thin layers were subsequently heat treated and characterized to understand their optical, electrical, morphological and structural properties. Accordingly, CdS and CdTe semiconductor materials deposited on glass/FTO (7 Ω/sq) substrates have exhibited better optoelectronic qualities and hence, endorse the requirement of individual growth parameter optimization for each type of TCO glass substrate for the production of good quality CdS and CdTe thin films in photovoltaic device fabrications.

Effects of {001} Facet of Anatase TiO2 Single-crystalline Nanosheets on Photoexcited Electron Transfer from Near-infrared Dye-sensitizer

Single-crystalline anatase TiO2 nanosheets predominantly exposing the {001} facet at a surface fraction of more than 75% were constructed on transparent conductive oxide glass substrates. Application of these nanoarchitectures of TiO2 demonstrated photoelectric conversion while using near-infrared absorbing dye-sensitizer. In contrast, regular mesoporous TiO2 films with a much larger effective surface area did not exhibit a photoelectric response with the same dye-sensitizer. The results obtained here emphasize the importance of the contacted crystalline facet of TiO2 in photoinduced charge separation for minimizing the potential drop for interfacial charge-carrier transfer in dye-sensitized solar cell systems. Especially, the observed improvement of electron injection by contacted facet could contribute to the efficient photoexcited electron injection from near-infrared dye-sensitizers possessing relatively small HOMO–LUMO gap.

Synthesis of Solution-Processed Cu2ZnSnSe4Thin Films on Transparent Conducting Oxide Glass Substrates

Cu2ZnSnSe4 (CZTSe) thin films were synthesized on transparent conducting oxide glass substrates via a simple, non-toxic, and low-cost process using a precursor solution paste. A three-step heating process (oxidation, sulfurization, and selenization) was employed to synthesize a CZTSe thin film as an absorber layer for use in thin-film solar cells. In particular, we focused on the effects of sulfurization conditions on CZTSe film formation. We found that sulfurization at 400 °C involves the formation of secondary phases such as CuSe2 and Cu2SnSe3, but they gradually disappeared when the temperature was increased. The formed CZTSe thin films showed homogenous and good crystallinity with grain sizes of approximately 600 nm. A solar cell device was tentatively fabricated and showed a power conversion efficiency of 2.2% on an active area of 0.44 cm 2 with an open circuit voltage of 365 mV, a short current density of 20.6 mA/cm 2 , and a fill factor of 28.7%.

Growth and characterization of ZnO/ZnTe core/shell nanowire arrays on transparent conducting oxide glass substrates

We report the growth and characterization of ZnO/ZnTe core/shell nanowire arrays on indium tin oxide. Coating of the ZnTe layer on well-aligned vertical ZnO nanowires has been demonstrated by scanning electron microscope, tunneling electron microscope, X-ray diffraction pattern, photoluminescence, and transmission studies. The ZnO/ZnTe core/shell nanowire arrays were then used as the active layer and carrier transport medium to fabricate a photovoltaic device. The enhanced photocurrent and faster response observed in ZnO/ZnTe, together with the quenching of the UV emission in the PL spectra, indicate that carrier separation in this structure plays an important role in determining their optical response. The results also indicate that core/shell structures can be made into useful photovoltaic devices.

Electrodeposited tin selenide thin films for photovoltaic applications

Tin selenide thin films of about 300nm thickness were electrodeposited on SnO2:F coated transparent conductive oxide glass substrates. The optimum deposition potential was determined from cyclic voltammetry measurements. The films were polycrystalline with orthorhombic structure and the grain size was about 18nm. SEM images showed a highly porous film structure. The band gap estimated from optical spectra of these films showed absorption due to direct transition occurring at 1.1eV. Characteristic vibrational modes of the SnSe were observed in the Raman spectrum. The films are p-type, photosensitive, and the conductivity measured in dark was in the range of 10−5Ω−1cm−1. A prototype CdS/SnSe photovoltaic device showed an open circuit voltage of 140mV and short circuit current density 0.7mA/cm2.

Blocking Layers Deposited on TCO Substrate and Their Effects on Photovoltaic Properties in Dye-Sensitized Solar Cells

ABSTRACT: In this review, we have investigated the effect of TiO 2 -based blocking layers (t-BLs), deposited ona transparent conductive oxide (TCO)-coated glass substrate, on the photovoltaic performance ofdye-sensitized solar cells (DSSCs). The t-BL was deposited using spin-coating or sputteringtechnique, and its thicknesses were varied to study the influence of the thin TiO 2 layer in betweentransparent conducting glass and nanocrystalline TiO 2 (nc-TiO 2 ). The DSSC with the t-BL showedthe improved adhesion and the suppressed charge recombination at a TCO glass substrate thanthose without the t-BL, which led to the higher conversion efficiency. Keywords: Dye-sensitized solar cell, Blocking layers, Transparent conducting oxides, Chargerecombination, Adhesion properties Received May 27, 2011 : Accepted June 3, 2011 1. Introduction Dye-sensitized solar cells have been extensivelystudied since their discovery in 1991 by Gratzel’s researchgroup 1) because they have been considered as a goodalternative to conventional silicon photovoltaic cells dueto their low production costs and colorful characteristics.As a consequence of this special attention, DSSCs withenergy conversion efficiencies higher than 11% have beenobtained using nc-TiO

CdS/CdSe cosensitized oriented single-crystalline TiO2 nanowire array for solar cell application

Vertically oriented single-crystalline TiO2 nanowires array was grown on transparent conductive oxide glass substrate, and then CdS and CdSe quantum dots (QDs) were deposited on nanowires to form a TiO2/CdS/CdSe core-shell structure films. The optical properties of films with different layers of QDs were compared. The QD sensitized solar cells (QD-SSCs) were assembled and the effect of coating cycles of QDs on the photovoltaic performance was investigated. Under optimum parameters, QD-SSCs assembled with 5 μm thick TiO2 nanowires film exhibited a short-circuit current density of 7.92 mA cm−2, an open-circuit voltage of 0.40 V, and a power conversion efficiency of 1.14%.

Tin Sulfide Thin Films by Pulse Electrodeposition: Structural, Morphological, and Optical Properties

Tin sulfide thin films, typically 350 nm thick, were deposited on -coated transparent conductive oxide glass substrates by pulse electrodeposition. The applied potentials were and vs saturated calomel electrode with pulse on/off durations of 10 s. The films crystallized in the orthorhombic structure corresponding to SnS (herzenbergite), with grain size varying in the range from a few nanometers to more than 100 nm. X-ray diffraction analysis shows an average size of 12 nm; however, scanning electron microscopy and transmission electron microscopy images show the presence of large crystallites with well-developed facets along with agglomerations of smaller crystallites. Estimation of the bandgap from the optical spectra of these films showed absorption due to direct transition occurring at 1.3 eV. Elemental compositions of these SnS samples determined using energy dispersive X-ray spectroscopy were 51.4 and 48.5%, respectively, for Sn and S. Raman spectra suggested the presence of traces of and . The surface analysis by X-ray photoelectron spectroscopy showed the presence of traces of metallic Sn. The films are photosensitive with a dark resistivity .

Effect of Heat-Treatment on Electron Transport Process in TiO2 Nanotube Arrays Prepared Through Liquid Phase Deposition for Dye-Sensitized Solar Cells

Nanotube arrays of were synthesized by using a template of ZnO nanorod arrays on fluorine-doped transparent conducting oxide glass substrate by liquid phase deposition method. Dye N719-sensitized photoelectrochemical cells comprising nanotube arrays were fabricated and characterized. With an increase in the calcination temperature, the anatase content of the crystallized film increased and the conduction band of shifted toward a negative potential, resulting in an increase in the cell performance in terms of the short-circuit photocurrent density and open-circuit voltage.

High-density arrays of low-defect-concentration zinc oxide nanowire grown on transparent conducting oxide glass substrate by chemical vapor deposition

High-density ZnO nanowire arrays with low defect concentrations were directly grown on transparent conducting oxide glass substrates under catalyst-free and low temperature conditions by chemical vapor deposition (CVD). A possible growth mechanism of the nanowires is studied. The experiments indicate that correct levels of supersaturation and evaporation temperature are beneficial to the growth of ZnO nanowires. Photoluminescence exhibits a weak ultraviolet emission at 380nm and a strong green emission at 495nm. While using a double-tube growth system, the visible light emission diminishes and the 380nm emission is the only emission, suggesting that ZnO nanowires with few defects can be prepared using the present CVD technique at low temperature.

Vertically Aligned Single Crystal TiO2 Nanowire Arrays Grown Directly on Transparent Conducting Oxide Coated Glass: Synthesis Details and Applications

Single-crystal one-dimensional (1D) semiconductor architectures are important in materials-based applications requiring a large surface area, morphological control, and superior charge transport. Titania has widespread utility in applications including photocatalysis, photochromism, photovoltaics, and gas sensors. While considerable efforts have focused on the preparation of 1D TiO2, no methods have been available to grow crystalline nanowire arrays directly onto transparent conducting oxide (TCO) substrates, greatly limiting the performance of TiO2 photoelectrochemical devices. Herein, we present a straightforward low temperature method to prepare single crystal rutile TiO2 nanowire arrays up to 5 microm long on TCO glass via a non-polar solvent/hydrophilic substrate interfacial reaction under mild hydrothermal conditions. The as-prepared densely packed nanowires grow vertically oriented from the TCO glass substrate along the (110) crystal plane with a preferred (001) orientation. In a dye sensitized solar cell, N719 dye, using TiO2 nanowire arrays 2-3 microm long we achieve an AM 1.5 photoconversion efficiency of 5.02%.

A facile route to TiO 2 nanotube arrays for dye-sensitized solar cells

Nanotube arrays of TiO 2 were synthesized by using a template of ZnO nanorod arrays on fluorine-doped SnO 2 (FTO) transparent conducting oxide glass substrate by liquid phase deposition (LPD) method. Dye (N719) sensitized solar cells (DSCs) comprising the TiO 2 nanotube arrays were fabricated under the various conditions of the calcined temperature in the range of 300–500 °C. The sintering temperature drastically affected the film crystallinity. Cell performances of the DSCs based on the TiO 2 nanotube arrays with different cryatalinities were characterized and compared. It was found that the content of crystalline phase of anatase TiO 2 nanotube arrays increased on raising the calcination temperature up to 500 °C and resulting in enhancement of the cell performance of DSCs in terms of the short-circuit photocurrent density.

Portable, parallel grid dye-sensitized solar cell module prepared by screen printing

Screen-printing technology is used to fabricate large dye-sensitized solar cells (DSSCs). The high series-resistance associated with transparent conductive oxide glass substrates causes poor performance in large DSSCs especially at an exposure of 1 sun. The DSSC design has an embedded silver grid; a fluorine-doped tin oxide (FTO) glass substrate and stripe type titanium dioxide (TiO2) active layers introduced by screen-printing. The counter electrode is prepared from a screen printable paste based on hexachloro platinic acid. A DSSC module, which consists of five stripe-type working electrodes on a 5 cm × 5 cm, embedded silver grid FTO glass substrate, shows stable performance with an energy conversion efficiency of 5.45% under standard test conditions. © 2006 Elsevier B.V. All rights reserved.

Cubic PbS thin films on TCO glass substrate by galvanic technique

We report an electrochemical deposition of PbS thin films on SnO 2:F coated Transparent Conducting Oxide (TCO) glass substrates from a solution of EDTA, Pb(OAc) 2 and Na 2S 2O 3. A Pb strip acted as a sacrificial anode, while the TCO glass was the cathode. No external bias was applied. The deposition of PbS thin films was pH sensitive and a pH around 3 was found to be optimum for film deposition. The deposition was carried out at 80 °C, with stirring of the solution. X-ray diffraction studies revealed that the PbS films were of cubic phase. Scanning electron microscope image analysis showed a highly compact surface morphology. IR spectrum yielded an energy band gap around 0.4 eV. A.C. current–voltage ( I– V) measurements were carried out using gold as one of the contacts. It was found that the PbS film formed an ohmic contact when the other electrode was also gold, however, a Schottky junction resulted, when the second contact was TCO.

Galvanic deposition of hexagonal ZnO thin films on TCO glass substrate

We report an electrochemical deposition of ZnO thin films on SnO2:F coated Transparent Conducting Oxide (TCO) glass substrates from a solution of Zn(NO3)2. A Zn rod acted as a sacrificial anode, while the TCO glass was the cathode. No external bias was applied. The deposition of ZnO thin films was pH sensitive and a pH between 5 and 6 was found to be optimum for film deposition. The deposition was carried out at 60 and 80 °C, with stirring of the solution. X-ray diffraction studies revealed that the ZnO films were of hexagonal phase. Scanning electron microscope (SEM) images showed prominent hexagonal micro-grains with vertical columnar growth. Optical absorption spectra yielded an energy band gap around 3.3 to 3.4 eV. A.C. current–voltage (I–V) and capacitance–voltage (C–V) measurements were carried out using colloidal silver paste as one of the contact. It was found that the ZnO film formed a Schottky junction and the TCO/ZnO/Ag system could be used as an electrical switching device.

Selenium-Modified Titanium Dioxide Photochemical Diode/Electrolyte Junctions: Photocatalytic and Electrochemical Preparation, Characterization, and Model Simulations

The photoelectrochemical behavior of TiO2 thin film electrodes, photocatalytically modified with Se islands, is described. The TiO2 thin films were electrodeposited on transparent conducting oxide glass substrates. The resultant electrode forms a n-TiO2/p-Se "photochemical diode" which, in turn, contacts an electrolyte phase. Both transient photocurrent profiles (in response to excitation light that is switched on or off) and steady-state current-potential curves in response to chopped irradiation are considered. We show that the relative dominance of the contributions from the TiO2 and Se components to the overall response of the photochemical diode/electrolyte junction crucially depends on the wavelength distribution of the excitation light source. A simple equivalent circuit representation of this junction is presented, comprised of a photodiode in parallel with two photodiodes connected in series back-to-back. Simulations of the transient and steady-state photoelectrochemical response of this system are presented, and are shown to be in good agreement with the corresponding experimental profiles.

Microwave calcination of thin TiO2films on transparent conducting oxide glass substrates

Microwave calcination of thin TiO₂films on transparent conducting oxide glass substrates