To Transparent Conducting Oxide Research Articles

Electrical and optical properties of Ga-doped ZnO thin films deposited by DC magnetron sputtering

The electrical and optical properties of Ga-doped ZnO (GZO) thin film prepared by direct current (dc) magnetron sputtering were investigated. The GZO thin film was deposited on a glass substrate at a substrate temperature (Ts) of room temperature (RT), 150 °C, and 200 °C using DC power of 100 W and an Ar gas flow rate of 450 sccm. The thickness of films was maintained at about 200 nm by controlling the deposition rate of about 12.5 nm/minute. The result showed that the electrical properties improved with increasing Ts. The films deposited at Ts of 200 °C showed the lowest resistivity, highest hall mobility, and carrier concentration compared to other Ts. The average transmittance of the films in the visible range (380-750 nm) was approximately 86.04%. The value of the optical band gap (Eg) was approximately 3.8 eV. The results suggested that GZO films deposited by DC magnetron sputtering at Ts of 200 °C can be applied to transparent conducting oxide (TCO) as an electrode in optoelectronic applications such as solar cells, LEDs and display technology.

Pure carbon conductive transparent electrodes synthetized by a full laser deposition and annealing process

One of the biggest challenge that face optoelectronic and photovoltaic devices is the necessity to provide a reliable alternative to transparent conducting oxide (TCO) like Indium Thin Oxide (ITO). We recently published a study proposing a method to produce transparent conductive electrodes only based on carbon materials. In a first step, we use the Pulsed Laser Deposition (PLD) to produce high performance DLC. Those thin films own very interesting properties in kindship with diamond, like high transparency in the visible range, chemical inertness and biocompatibility. In addition, the DLC is a perfect electrical insulator and presents a relative high opacity in ultra-violet (UV). This particularity has a great interest to perform, in a second step, UV laser annealing over the DLC surface. The aim is to break the existing diamond bindings (sp3 hybridization) on the surface and allow atoms being reorganized in graphitic bindings (sp2 hybridization). We demonstrate that the increase of atomic graphitic bindings leads to a valuable surface conductivity. According to optimized annealing parameters, the surface conductivity reaches values comparable to ITO. We also show that the laser treatments only sparsely affects the DLC transparency. Moreover, this full laser-based process remains compatible with the standard microelectronic technological steps.

UV laser annealing of Diamond-Like Carbon layers obtained by Pulsed Laser Deposition for optical and photovoltaic applications

One of the biggest challenge in optoelectronic devices is the necessity to provide a viable and reliable alternative to Transparent Conducting Oxide (TCO) and especially to Indium Tin Oxide (ITO). Graphene is a widely studied material and one of the best alternative to be used as conductive and transparent electrodes. It is well known that the difficulty to transfer graphene on another substrate is a serious limitation for its use on large scale devices. In this work, we explore Diamond-like Carbon (DLC) thin films prepared by Pulsed Laser Deposition (PLD) to be used as substrate for graphene-like layers. DLC thin films are excellent candidates due to their visible-range transparency being also a very good electrical insulator. Transmission measurements show the UV opaque character of the DLC layers, independently to the experimental parameters used to produce them. Thus, top-hat UV laser surface annealing can strongly modify the DLC thin film structure in order to bring conductivity to the first atomic layers. Raman spectroscopy and X-ray photoemission spectroscopy permit to confirm the graphitic character of the DLC surface. Optimizing PLD as well as laser annealing parameters is explored in detail in order to obtain comparable performances (conductivity and transparency) to ITO typical properties. Moreover, using a full-based laser process offers a complete compatibility with all technical steps of the microelectronic domain.

Simulation study towards high performance transparent-conductive-oxide free perovskite solar cells using metal microcavity and optical coupling layer

The microcavity perovskite solar cells (PSCs) are designed by sandwiching the perovskite layer between the ultrathin Ag and opaque Ag electrodes. Compared to transparent-conductive-oxide (TCO) based PSCs, the microcavity PSCs with the bare Ag electrode show the poor optical performance due to the transmittance limit of Ag film. By introducing an optical coupling layer, the remarkably improved transmittance of the Ag electrode and enhanced light absorption in the perovskite layer are obtained. Furthermore, the better light absorption is available by adopting an optical spacer, and the resulted microcavity PSCs achieve the comparable or even higher $J_{{\text{SC}}}$ than TCO-based PSCs. This provides a guideline to design and fabricate efficient TCO-free PSCs.

SINTESIS LAPISAN TIPIS (THIN FILM) SnO2 DAN SnO2:Al MENGGUNAKAN TEKNIK SOL-GEL SPIN COATING PADA SUBSTRAT KACA DAN QUARTZ

This study has successfully synthesized SnO2 and SnO2 thin films by doping aluminum (Al) using the technique of sol-gel spin coating on glass and quartz substrates. The basic materials are Tin (II) chloride dihydrate (SnCl2.2H2O) and ethanol (C2H5OH) as solvent. Material for doping is AlCl3 as much as 0.027 g, 0.053 g and 0.08 g to get Al dopant concentration of 5%, 10% and 15% respectively. The substrate used in this study are glass and quartz with the dimension of 10 mm x 10 mm x 3 mm. Detergent water, distilled water and 70% alcohol were used for the preparation of the substrates. Pure SnO2 sol solution was obtained by dissolving SnCl2.2H2O in ethanol, and SnO2:Al was obtained by adding AlCl3 to the solution of SnO2. The stirring process was done by using a hot plate magnetic stirrer to obtained a homogeneous solution (transparent). Sol solution of pure SnO2 and SnO2:Al were allowed for 24 hours as maturation (aging) process. Solution deposition on a substrate was done with a rotary speed of 2000 rpm for 3 minutes. Heating process was done at the annealing temperature of 200°C to 400°C by using a furnace for 1 hour to grow the crystalline of thin films. This thin films are very appropriate when applied to transparent conductive oxide (TCO) materials with high transparency and conductive character of tin (Sn) and aluminum (Al)Keyword: SnO2‚ aluminum‚ sol-gel, spin coating, substrate

Low-cost nanocarbon electrodes on arbitrary fibrous substrates as efficient bifacial photovoltaic wires

Ultralow-cost nanocarbon was deposited on arbitrary fibers and used as an efficient catalytic electrode, leading to transparent conductive oxide (TCO) free and bifacial photovoltaic wires with an optimal efficiency of 6.09%.

Vertically aligned anatase TiO2 nanotubes on transparent conducting substrates using polycarbonate membranes

6 μm-thick, anatase TiO2 nanotubes (NTs) that were vertically aligned to transparent conducting oxide (TCO) substrates were prepared using a sol–gel process and track-etched polycarbonate (PC) membranes.

The Emitter Having Microcrystalline Surface in Silicon Heterojunction Interdigitated Back Contact Solar Cells

In producing the Si heterojunction interdigitated backcontact solar cells, we investigated the feasibility of applying amorphous Si emitter having considerable crystalline Si phase at the facing to transparent conducting oxide (TCO) layer. Prior to evaluating electrical property, we characterized material nature of hydrogenated microcrystalline p-type silicon (µc-p-Si:H) as crystallized fraction, surface morphology, bonding kinds in thin films and then surface passivation quality finally. The diode and interface contact characteristics were induced by the simple test device and then current–voltage (I–V) curve showed more linearity in µc/hydrogenated amorphous silicon (a-Si:H) emitter case. We fabricated heterojunction back contact (HBC) solar cells using p/n interdigitated structure and acquired the 23.4% efficiency in cell size with performance parameters as open-circuit voltage (Voc) 723 mV, short-circuit current density (Jsc) 41.8 mA/cm2, fill factor (FF) 0.774, in the cell size (at 2×2 cm2).

The Emitter Having Microcrystalline Surface in Silicon Heterojunction Interdigitated Back Contact Solar Cells

In producing the Si heterojunction interdigitated backcontact solar cells, we investigated the feasibility of applying amorphous Si emitter having considerable crystalline Si phase at the facing to transparent conducting oxide (TCO) layer. Prior to evaluating electrical property, we characterized material nature of hydrogenated microcrystalline p-type silicon (µc-p-Si:H) as crystallized fraction, surface morphology, bonding kinds in thin films and then surface passivation quality finally. The diode and interface contact characteristics were induced by the simple test device and then current–voltage (I–V) curve showed more linearity in µc/hydrogenated amorphous silicon (a-Si:H) emitter case. We fabricated heterojunction back contact (HBC) solar cells using p/n interdigitated structure and acquired the 23.4% efficiency in cell size with performance parameters as open-circuit voltage (Voc) 723 mV, short-circuit current density (Jsc) 41.8 mA/cm2, fill factor (FF) 0.774, in the cell size (at 2×2 cm2).

Transparent, Conducting ATO Thin Films by Epoxide-Initiated Sol–Gel Chemistry: A Highly Versatile Route to Mixed-Metal Oxide Films

A robust synthesis approach to transparent conducting oxide (TCO) materials using epoxide assisted sol-gel chemistry is reported. The new route utilizes simple tin and antimony chloride precursors in aqueous solution, thus eliminating the need for organometallic precursors. Propylene oxide acts as a proton scavenger and drives metal hydroxide formation and subsequent polycondensation reactions. Thin films of antimony-doped tin oxide (ATO) were prepared by dip-coating of mixed metal oxide sols. After annealing at 600 °C in air, structural, electrical and optical properties of undoped and Sb-doped tin oxide films were characterized. Single layer films with 5 mol % Sb doping exhibited an optical transparency which was virtually identical to that of the plain glass substrate and an electrical resistivity of 2.8 × 10(-2) Ω cm. SEM and AFM analysis confirmed the presence of surface defects and cracks which increased with increasing Sb dopant concentration. Multiple depositions of identical ATO films showed a roughly 1 order of magnitude decrease in the film resistivity after the third layer, with typical values below 5 × 10(-3) Ω cm. This suggests that a second and third deposition fill up residual cracks and defects in the first layer and thus brings out the full performance of the ATO material. The epoxide-assisted sol chemistry is a promising technique for the preparation of mixed oxide thin film materials. Its superiority over conventional alkoxide and metal salt-based methods is explained in the context of a general description of the reaction mechanism.

Enhanced luminescence related to transparent conductive oxide in ZnS-based EL device fabricated by screen printing method

This experiment is focused to characterize electroluminescence (EL) properties related to transparent conductive oxide (TCO) like In2O3 or SnO2 being dispersedly inserted into the two different layered structures fabricated by screen printing method. X-ray diffraction and FE-SEM measurement were carried out to characterize the material properties of the ZnS-based EL devices depending on the layered structures and the material constitutions. The results show that the enhanced EL intensity with the TCO insertion is approximately 1.2 times greater than TCO-free sample under the 1-layered structure while in no significant improvement of EL intensity is observed under the 2-layered EL structure. But for the EL intensity comparison under the device structure, 2-layered EL structure having a separate dielectric layer is 1.4 times brighter than the 1-layered structure.

Electrochemical deposition of ordered macroporous ZnO on transparent conducting electrodes

Large area macroporous zinc oxide (ZnO) films have been prepared by colloidal crystal templating on to transparent conducting oxide (TCO) substrates using an electrochemical deposition technique. Characterisation by scanning electron microscopy (SEM) reveals changes in the microstructure of the ZnO films as the template diameter and deposition potential are varied. Analysis by X-ray diffraction (XRD) and UV–vis spectroscopy show that the structural variations do not influence the inherent properties of the ZnO. We attribute the observed microsturctural differences to variations in growth kinetics in response to the applied deposition potential and solution transport phenomena that are controlled by the template dimensions. The optical properties of the structures exhibit two distinct features, originating from the optical band-gap of the ZnO and the photonic band-gap of the ordered macroporous structure.

Influence of seed layer treatment on ZnO growth morphology and their device performance in dye-sensitized solar cells

Abstract The surface modification of the ZnO seed layer by ultrasonic mediated rinsing (UMR) was realized as an efficient tool for growing highly branched hierarchical ZnO nanorods through multistage approach. The hierarchical ZnO nanostructure achieved through UMR approach was performed as the photoanodes in dye-sensitized solar cells (DSSCs). The DSSC based on the novel branched network resulted in energy conversion efficiency ( η ) of 1.1% ( J sc = 4.7 mA cm −2 ). The improved device performance was ascribed to the (a) high internal surface area for efficient dye adsorption, (b) rapid electron pathway for charge transport from ZnO to transparent conducting oxide (TCO) substrate and (c) producing random multiple scattering of the light within the hierarchical network leading to photon localization, thereby increasing the probability of the interaction between the photons and the dye molecules of the branched network. The beneficial effect of the UMR approach was distinguished by fabricating DSSCs based on randomly oriented ZnO nanorods prepared by conventional rinsing (CR), which offered lower conversion efficiency η = 0.7% ( J sc = 3.8 mA cm −2 ). The exploration of novel hierarchical ZnO nanorods grown in the present work by the low temperature solution growth techniques may pave way to bring out photoanode material on flexible substrates for the fast growing DSSCs devices.

GZO透明導電膜へのNd:YAGレーザによるアニーリング効果

In order to cope with the depletion of iudium, a strong interest has been recently turned to transparent conducting oxide (TCO) films based on a zinc oxide system. Focusing to this theme, it was tried to fabricate Gallium-doped zinc oxide (GZO) TCO films. But, it was difficult to make good films of GZO at low temperature. Therefore, it was tried to use laser-annealing-method for improved characteristics of GZO films. Approximately 200-nm-thick 5.0 wt.% Ga-doped zinc oxide (GZO: 5.0 wt.% Ga2O3) films have been deposited on glass substrates at Room Temperature by pulsed laser deposition (PLD) using the fourth harmonic generation (FHG) of Nd: YAG laser (λ=266 nm). In order to reduce resistivity of as-deposited films, annealing process was carried out by Nd:YAG (FHG) laser with laser energy density of 40 mJ/cm2. As a result, the resisivity was improved from 8.16×10-4 to 6.27×10-4 Ω·cm (improvement effect of 23.2 %). An average transmittance of more than 85% in the visible region was obtained for the fabricated.