The characteristics of indium zinc oxide (IZO)–Ag–IZO multilayer grown on a polyethylene terephthalate (PET) substrate were investigated for flexible organic light-emitting diodes (OLEDs). The ...IZO–Ag–IZO (IAI) multilayer anode exhibited a remarkably reduced sheet resistance of 6.93 Ω/□ and a high transmittance of 84.8%, despite the very thin thickness of the IZO (30 nm) layer. In addition, it was shown that electrical and optical properties of IAI anodes are critically dependent on the thickness of the Ag layer, due to the transition of Ag atoms from distinct islands to continuous films at a critical thickness (12 nm). Moreover, the IAI/PET sample showed more stable mechanical properties than an amorphous ITO/PET sample during the bending test due to the existence of a ductile Ag layer. The current density–voltage–luminance characteristics of flexible OLEDs fabricated on an IAI/PET substrate was better than those of flexible OLEDs fabricated on an ITO/PET substrate. This indicates that IAI multilayer anodes are promising flexible and transparent electrodes for flexible OLEDs.
In this study, thin-film transistors (TFTs) with amorphous indium-zinc oxide (IZO) channel were fabricated by plasma-enhanced atomic layer deposition (PEALD). By optimizing the cyclic ratio of ...laminated ZnO/In2O3, the IZO-TFTs demonstrated a high field-effect channel mobility (<inline-formula> <tex-math notation="LaTeX">\mu </tex-math></inline-formula> FE) of 42.19 cm2/V s, a threshold voltage (<inline-formula> <tex-math notation="LaTeX">{V} _{\text {th}} </tex-math></inline-formula>) of -0.63 V, and a subthreshold swing (SS) of 0.27 V/decade. Moreover, these TFTs exhibited excellent stability during the accelerated test of positive bias temperature stress (PBTS) and negative bias temperature stress (NBTS). This enhanced stability can be attributed to the reduction of defect states achieved through the structural design of the stacked subsequence.
To control the work function and the interface of transparent anodes for use in organic solar cells (OSCs), we fabricated an amorphous Zn-doped In2O3 (IZO) films with graded MoO3 top layers by using ...a graded sputtering technique. Electrical, optical, structural, and morphological properties of the MoO3 graded IZO films (MIZO) were investigated in detail by studying MIZO films with various thickness of the MoO3 graded layer. Graded sputtering of the MoO3 layer on the top region of IZO films led to the high work function of 5.23eV for the amorphous IZO, which was higher than that of the MoO3/IZO double layer, even though MIZO had resistivity similar to that of the IZO single layer. Due to the high work function and high transparency of the MIZO films, OSCs based on the MIZO anode exhibited a power conversion efficiency (PCE) of 3.2%, greater than that of OSCs based on IZO single layer and MoO3/IZO double layer anodes. Based on Kelvin probe measurements and transmission electron microscope examinations, we suggested a possible hole extraction mechanism at the interfaces between the MIZO anode and the PEDOT:PSS buffer layer to explain the higher PCE of OSCs based on MIZO anodes. The successful operation of OSCs on graded MIZO indicated that the graded sputtering technique is a promising coating process allowing modification of surface properties of amorphous IZO anodes without requiring additional solution coating processes.
Display omitted
•Characteristics of MoO3-graded IZO films were investigated for organic solar cells.•The effect of MoO3 graded layer on work function of IZO films was investigated.•Interface between PEDOT:PSS and MoO3 graded IZO films in OSCs.
An amorphous indium gallium zinc oxide (a‐IGZO) layer is deposited on very thin conductive amorphous indium zinc oxide (a‐IZO) thin film to demonstrate high‐performance, coplanar thin‐film ...transistors (TFTs) with dual‐channel oxide semiconductor architecture. Based on material properties, a conduction band offset (∆EC) of ≈0.28 eV between a‐IZO and a‐IGZO layers and a conduction band bending of ≈0.3 eV at a‐IGZO/gate insulator (GI) interface exist. Through the electrical characterization, high field‐effect mobility (μFE) of ≈50 cm2 V−1 s−1, a positive threshold voltage (VTh) of ≈2.3 V, and low off‐current (IOFF) of <1 pA in coplanar a‐IZO/a‐IGZO TFT are demonstrated. The electron accumulation (>5 × 1018 cm−3) at both the a‐IZO/a‐IGZO and a‐IGZO/GI interfaces confirm the dual‐channel conduction. The bottom a‐IZO channel significantly contributes to increasing drain current (ID) due to large electron density (≈1019 cm−3). The dual‐channel coplanar TFT with a‐IGZO/IZO provides a guideline for overcoming the trade‐off between high μFE and positive VTh control for stable enhancement mode operation with increased ID.
Coplanar thin‐film transistor (TFT) with a combination of low mobility amorphous InGaZnO and high mobility amorphous InZnO semiconductors is proposed for high mobility, low off‐current, and positive threshold voltage (VTh) for large‐area display applications. The TFTs exhibit a high mobility of 49.5 cm2 V−1 s−1 with positive VTh (2.30 V).
The carrier transport mechanisms in indium-zinc-oxide thin-film transistors are investigated in this paper by use of low-frequency noise (LFN). First, LFNs are measured in the range from 10 to 300 K. ...The measured noises show that the device is varied from an interface-dominated device to a bulk-dominated device at lower temperature, which induce to the variation of the power coefficient of normalized noise against the effective gate voltage. Moreover, the measured noise increases with decreasing temperature in the range of 200-300 K. Below 200 K, the measured noise decreases with the decrement of temperature, which dominated by thermally activated conduction mechanism in the range of 80-200 K and dominated by variable range hopping theory below 80 K. The variations of flat-band voltage spectral density and average Hooge's parameter with temperature are also extracted and discussed. The calculated fluctuation related defects increase significantly with decreasing temperature.
A comprehensive study on the hydrogen (H2) gas sensing performance of a novel chemoresistive gas sensor is presented in this work. This sensor is synthesized by an In-Zn-O (IZO) thin film and ...palladium nanoparticles (Pd NPs) on a sapphire (Al2O3) substrate. The relevant elemental, compositional, and chemical state properties are systematically investigated for the fabricated Pd NP/IZO sensor. The use of Pd NPs effectively enhances the surface area to volume (SA/V) ratio and related catalytic capability. This significantly improves the hydrogen sensing characteristics. In the experiment, the produced sensor achieves a higher sensing response SR of 1.59×104 under 1 % H2/air gas and a lower detectable content of 100 ppb H2/air at 250 °C. Importantly, the fabricated sensor reveals promised selectivity, reproducibility, and long-term (90 days) durability towards H2 gas. Therefore, the studied sensor offers a prominent choice for H2 gas detection.
•The Pd NP/ IZO sensor exhibited good sensing performance under 100 ppb H2 /air gas and demonstrated a wide detecting range.•The Pd NP/IZO sensor demonstrates the excellent selectivity towards hydrogen gas.•The Pd NP/ IZO sensor demonstrates and maintains stability throughout long-term testing.•The Pd NP/ IZO sensor exhibits a good linear relationship between the sensing response and concentration.
With rapid development toward transparent display, there is an urgent need for electrode with ultra‐high transparency. Here, based on IZO, we propose and experimentally demonstrate a composite ...cathode capable of efficient micro‐cavity effect within the emitting area and high transmittance in the non‐emitting area. We envision the composite cathode to find its applications in the next generation ultra‐high transparent display technology.
Ultraviolet (UV) photodetectors play an important role in numerous commercial and scientific applications. The UV photodetectors based on binary‐cation indium zinc oxide (InZnO) thin films exhibit ...great performance enhancement, compared with their single‐cation counterparts. However, UV photodetectors based on 1D InZnO nanowires could potentially exhibit more superior optoelectrical performance, due to the large surface‐to‐volume ratio and favorable carrier transport characteristics of nanowires. This work has combined combustion synthesis with electrospinning technique to efficiently fabricate InZnO nanowire‐based UV photodetectors. At the annealing temperature of 375 °C, the newly designed InZnO nanowire photodetectors exhibit excellent photoelectric performance under the irradiation of 310 nm UV light, including a photo‐to‐dark current ratio of 1.2 × 104, a photo responsivity of 2.8 × 103 A W–1, and a high detectivity of 2.4 × 1016 Jones. This study not only demonstrates the opportunity to construct new‐generation transparent electronics based on 1D metal oxide nanowires but also sheds new light on how to further decrease the annealing temperature of metal oxide nanowire devices for low‐temperature fabrication processes.
Combustion synthesis with electrospinning technique is combined to efficiently fabricate InZnO nanowire‐based ultraviolet photodetectors. The annealing temperature is lowered to 375 °C, and the obtained ultraviolet photodetectors exhibit a good photo‐to‐dark current ratio of 1.2 × 104, a photo responsivity of 2.8 × 103 A W‐1 and a high detectivity of 2.4 × 1016 Jones.
In this letter, we report solution-processed, high-performance Indium-Zinc-Oxide (IZO) thin-film transistors (TFTs). The annealing temperature of IZO films are studied and found that devices annealed ...at 350 °C exhibit the best performance. With the use of a thin Al x O y layer as the gate dielectric, one-volt IZO TFTs are demonstrated, showing a high current on/off ratio of > 10 5 , a high mobility over 10 cm 2 /Vs, and a low subthreshold swing (SS) of 83 mV/dec, which is fairly close to the theoretical limit of SS at 300 K. Such a high device performance is also found comparable to those deposited using vacuum-based methods. As a result, the presented devices might possess a great potential in low-cost, low-power electronics.
Silicon solar cells are a mature PV technology; however, they are approaching their fundamental efficiency limit. Further efficiency improvements require a technological change towards silicon-based ...tandem solar cells, where a second absorber material with a higher band gap is stacked on top of silicon to reduce thermalization losses. For this purpose, perovskite-based solar cells have gained growing interest due to their rapid improvements in power conversion efficiencies, and promises of lower levelized costs of electricity. However, for perovskite-silicon tandem solar cells to surpass the current industry standard of silicon solar cells, efficiencies higher than 30 %, and long-term device stability are required.
This paper focuses on the goal of improving the overall device efficiency of perovskite-silicon tandem solar cells by optimization of the top transparent conductive oxide (TCO) electrode. Sputtering processes for the TCOs indium tin oxide (ITO) (standard DC sputtering with ceramic target) and indium zinc oxide (IZO) (reactive serial co-sputtering process - magnetron) were developed and investigated. TCO films were optimized with regard to their optical properties, quantified here as the absorption weighted with solar spectral data, as well as to their electrical characteristics assessed with 4-pt resistivity and Hall-effect measurements to quantify resistivity, carrier concentration, and mobility. The best performing TCOs were then integrated as front electrode in perovskite and perovskite-silicon tandem solar cells to evaluate their impact on the device level. The optimized IZO film resulted in up to 1 mA/cm2 improvement of short circuit current density of the tandem solar cells.
•ITO with lower absorption could be optimized using a 95/5 (In/Sn weight %) ceramic target and additional addition of small amounts of hydrogen.•The zinc doping concentration of the IZO was varied by means of a serial co-sputtering process using the Megatron™ technology.•IZO thin films show superior layer properties such as reduced parasitic absorptance and resistivity compared to ITO.•Perovskite–silicon tandem solar cells with IZO top contact (and ARC) reach up to 24.3 % efficiency in first trials.
