Compositional dependences of the optoelectronic properties of sol–gel derived CdO–ZnO composite films with volume ratio of Cd:Zn ranging from 1:0 to 0:1 (with a step of 1/4) have been studied. After ...heat treatments in air the prepared thin films were investigated by studying their structural, morphological, d.c. electrical and optical properties. X-ray diffraction (XRD) results suggest that the samples are polycrystalline and the crystallinity of them increased with Cd ratio. The average grain size is in the range of 20–53
nm. As composition and structure changed due to the Cd volume ratio, the order of the carrier concentration was varied from 10
16 to 10
20
cm
−3 with Cd ratio and the mobility increased from less than 2 to 45
cm
2
V
−1
s
−1. It was found that the transmittance and the band gap decreased as Cd ratio increased. The optical constants of the film were studied and the dispersion of the refractive index was discussed in terms of the Wemple–DiDomenico single oscillator model. The real and imaginary parts of the dielectric constant of the films were determined too. The volume energy loss (VELF) increases more than the surface energy loss (SELF) at their particular peaks. The third-order nonlinear polarizability parameter is higher for CdO–ZnO thin films with higher concentration of cadmium oxide.
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• Physical properties of the sol–gel derived CdO–ZnO nanostructured thin films prepared at different Cd content have been investigated. • The carrier concentration and carrier mobility of the samples were increased with Cd ratio whereas the resistivity was decreased. • The direct optical band gap shifted to the lower energy. • The refractive index and extinction coefficient increase with the increasing of Cd content. • The single-oscillator energy values are correlated with the optical band gap values by an empirical relation:
E
o
≈
2
E
g
. • With the increase in Cd content nonlinear optical susceptibility
χ
(3) increases.
Compositional dependence of the optoelectronic properties of sol–gel derived CdO–ZnO composite films with volume ratio of Cd:Zn ranging from 1:0 to 0:1 (with a step of 1/4) has been studied. After heat treatments in air the prepared thin films were investigated by studying their structural, morphological, d.c. electrical and optical properties. X-ray diffraction (XRD) results suggest that the samples are polycrystalline and the crystallinity of them increased with Cd ratio. The average grain size is in the range of 20–34
nm. As composition and structure changed due to the Cd volume ratio, the order of the carrier concentration was varied from 10
16 to 10
20
cm
−3 with Cd ratio and the mobility increased from less than 2 to 45
cm
2
V
−1
s
−1. It was found that the transmittance and the band gap decreased as Cd ratio increased. The optical constants of the film were studied and the dispersion of the refractive index was discussed in terms of the Wemple–DiDomenico single oscillator model. The real and imaginary parts of the dielectric constant of the films were also determined. The volume energy loss (VELF) increases more than the surface energy loss (SELF) at their particular peaks. The third-order nonlinear polarizability parameter is higher for CdO–ZnO thin films with higher concentration of cadmium oxide.
Despite the fact that antimony triselenide (Sb2Se3) thin‐film solar cells have undergone rapid development in recent years, the large open‐circuit voltage (VOC) deficit still remains as the biggest ...bottleneck, as even the world‐record device suffers from a large VOC deficit of 0.59 V. Here, an effective interface engineering approach is reported where the Sb2Se3/CdS heterojunction (HTJ) is subjected to a post‐annealing treatment using a rapid thermal process. It is found that nonradiative recombination near the Sb2Se3/CdS HTJ, including interface recombination and space charge region recombination, is greatly suppressed after the HTJ annealing treatment. Ultimately, a substrate Sb2Se3/CdS thin‐film solar cell with a competitive power conversion efficiency of 8.64% and a record VOC of 0.52 V is successfully fabricated. The device exhibits a much mitigated VOC deficit of 0.49 V, which is lower than that of any other reported efficient antimony chalcogenide solar cell.
A heterojunction post‐annealing treatment is utilized to suppress the nonradiative recombination for a highly competitive power conversion efficiency of 8.64% and a record open‐circuit voltage (VOC) of 520 mV in Sb2Se3 thin‐film solar cells. The VOC deficit of the device is lower than that of any other reported efficient antimony chalcogenide solar cells.
Binary Sb2Se3 semiconductors are promising as the absorber materials in inorganic chalcogenide compound photovoltaics due to their attractive anisotropic optoelectronic properties. However, Sb2Se3 ...solar cells suffer from complex and unconventional intrinsic defects due to the low symmetry of the quasi‐1D crystal structure resulting in a considerable voltage deficit, which limits the ultimate power conversion efficiency (PCE). In this work, the creation of compact Sb2Se3 films with strong 00l orientation, high crystallinity, minimal deep level defect density, fewer trap states, and low non‐radiative recombination loss by injection vapor deposition is reported. This deposition technique enables superior films compared with close‐spaced sublimation and coevaporation technologies. The resulting Sb2Se3 thin‐film solar cells yield a PCE of 10.12%, owing to the suppressed carrier recombination and excellent carrier transport and extraction. This method thus opens a new and effective avenue for the fabrication of high‐quality Sb2Se3 and other high‐quality chalcogenide semiconductors.
An injection vapor deposition (IVD) technology is designed and demonstrated. The IVD produces compact antimony selenide (Sb2Se3) films with high orientation preference, fewer deep‐level trap levels, and suppressed non‐radiative recombination, achieving a record power conversion efficiency of 10.12% for Sb2Se3 photovoltaics.
Recently we have reported the room temperature fabrication of transparent and flexible thin film transistors on a polyethylene terephthalate (PET) film substrate using an ionic amorphous oxide ...semiconductor (IAOS) in an In2O3–ZnO–Ga2O3 system. These transistors exhibit a field effect mobility of ∼10cm2 (Vs)−1, which is higher by an order of magnitude than those of hydrogenated amorphous Si and pentacene transistors. This article describes a chemical design concept of IAOS, and its unique electron transport properties, and electronic structure, by comparing them with those of conventional amorphous semiconductors. High potential of IAOS for flexible electronics is addressed.
The development of transparent p‐type oxide semiconductors with good performance may be a true enabler for a variety of applications where transparency, power efficiency, and greater circuit ...complexity are needed. Such applications include transparent electronics, displays, sensors, photovoltaics, memristors, and electrochromics. Hence, here, recent developments in materials and devices based on p‐type oxide semiconductors are reviewed, including ternary Cu‐bearing oxides, binary copper oxides, tin monoxide, spinel oxides, and nickel oxides. The crystal and electronic structures of these materials are discussed, along with approaches to enhance valence‐band dispersion to reduce effective mass and increase mobility. Strategies to reduce interfacial defects, off‐state current, and material instability are suggested. Furthermore, it is shown that promising progress has been made in the performance of various types of devices based on p‐type oxides. Several innovative approaches exist to fabricate transparent complementary metal oxide semiconductor (CMOS) devices, including novel device fabrication schemes and utilization of surface chemistry effects, resulting in good inverter gains. However, despite recent developments, p‐type oxides still lag in performance behind their n‐type counterparts, which have entered volume production in the display market. Recent successes along with the hurdles that stand in the way of commercial success of p‐type oxide semiconductors are presented.
Recent progress in hole‐transporting (p‐type) oxide materials and devices is reviewed. Material design strategies to improve the transport properties of five classes of oxides are discussed, including ternary Cu‐bearing oxides, binary copper oxides, tin monoxide, spinel oxides, and nickel oxides. In addition, the performance of semiconductor electronic devices based on p‐type oxides is reviewed, including thin‐film transistors, CMOS inverters, p–n‐junction diodes, memory devices, gas sensors, and electrochromics. The recent successes and the hurdles that stand in the way of commercial adoption of p‐type semiconductors are discussed.
Flexible and stretchable electronics represent today's cutting‐edge electronic technologies. As the most‐fundamental component of electronics, the thin‐film electrode remains the research frontier ...due to its key role in the successful development of flexible and stretchable electronic devices. Stretchability, however, is generally more challenging to achieve than flexibility. Stretchable electronic devices demand, above all else, that the thin‐film electrodes have the capacity to absorb a large level of strain (>>1%) without obvious changes in their electrical performance. This article reviews the progress in strategies for obtaining highly stretchable thin‐film electrodes. Applications of stretchable thin‐film electrodes fabricated via these strategies are described. Some perspectives and challenges in this field are also put forward.
Progress in strategies for obtaining highly stretchable thin‐film electrodes is reviewed. Such electrodes display tremendous potential in applications for flexible and stretchable electronics, such as stretchable displays, electronic skin, and wearable electronics.
Directional solution coating by the Chinese brush provides a facile approach to fabricate highly oriented polymer thin films by finely controlling the wetting and dewetting processes under ...directional stress. The biggest advantage of the Chinese brush over the normal western brush is the freshly emergent hairs used, whose unique tapered structure renders a dynamic balance of the liquid within the brush by multiple forces when interacting with the liquid. Consequently, the liquid is steadily held within the brush without any unexpected leakage, making the liquid transfer proceed in a well‐controllable manner. It is demonstrated that the Chinese brush coating enables the crystallization of the polymer and the self‐assembly of conjugated backbones to proceed in a quasi‐steady state via a certain direction, which is attributed to the controllable receding of the three‐phase contact line during the dewetting process by the multiple parallel freshly emergent hairs. The as‐prepared polymer thin films exhibit over six times higher charge‐carrier mobility compared to the spin‐coated films, which therefore provides a general approach for high‐performance organic thin‐film transistors.
Directional solution coating by the Chinese brush provides a facile approach to fabricate highly oriented polymer thin films by finely controlling the wetting and dewetting processes under the direction stress, and the as‐prepared polymer thin films exhibit over six times higher charge‐carrier mobility compared to the equivalent spin‐coated films. Therefore, a general approach is provided for high‐performance organic thin‐film transistors.
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