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The schematic diagram for the plating/stripping process of Zn. (a) Corrosion, by-products, and Zn dendrites are observed on a bare Zn electrode. (b) The Zn–THBA protective layer endows a dense and dendrite-free plating/stripping morphology.

Coal bumps occur frequently during coal mining, and monitoring of stress variations of coal mass is a prerequisite for coal bump prediction. To investigate a new method to reflect coal stress variation based on the pressure stimulated current (PSC), localized cyclic loading–maintaining–unloading experiments on coal samples were carried out and weak currents were measured. The response characteristics of PSCs with stress variations were analyzed, physical models showing the mechanisms of PSCs were established, and mathematical models explaining the relationships between PSCs and mechanical behaviors were derived. The results show that PSCs (tens of nA) flowing from the stressed volume to the un-stressed one can be observed upon load application. The currents are repeated with cyclic loading, load maintenance and unloading, which indicate that PSCs correspond well to stress variations. During loading, the PSC increases to a peak value at approximately 0.6 MPa and then it fluctuates until the stress stops increasing. When load is kept constant, the current decays exponentially to a stable value. During unloading, the PSC decreases at a lower rate when stress is greater than 0.6 MPa, after which it decreases at a higher rate to a minimum when stress is removed. Fitting results show that PSC increases exponentially with loading rate and that the stable current increases linearly with the maintained stress. Positive holes activated by the fracture of chemical bonds in the side chain of coal macro-molecules are believed to be the carriers, and the PSCs are generated due to the movement of the holes along stress gradients. Deduced formulas relating PSCs with coal mechanical behaviors show that PSC is proportional to strain rate; that is, PSC is inversely proportional to elastic modulus when stress rate is constant, as verified by the experimental results. These research results are expected to provide a new idea for monitoring of stress variations of coals during mining, which is significant for the prediction and early-warning of coal bumps.

The differences between mechanical properties and acoustic emission (AE) and electromagnetic radiation (EMR) characteristics of natural coal samples and saturated coal samples were analyzed by performing indirect tensile experiments. The experimental results show that coal samples go through four stages: compaction, elastic deformation, plastic deformation and failure. There is good correspondence between AE and EMR signals and the damage to coal samples. Under the action of water, tension strength of samples is reduced, while the plasticity is enhanced; also, the softening coefficient of tensile strength becomes 0.65. The saturated coal samples have a longer plastic stage and a more obvious AE quiet period. The damage to natural coal samples is tension damage, while that of saturated coal samples is due to tension and shear damage, which is more sufficient and irregular. EMR is still remarkable when AE is in a quiet period, and EMR is better for the precursor of rupture. Water weakens the generation and propagation of AE and EMR signals, especially in the earlier stage. AE and EMR damage factor D, defined by AE and EMR counts, has a better description of the damage degree in the indirect tensile process. This study is of great significance for research on the damage mechanism of water-bearing coal, the stability monitoring of water-bearing coals in the actual engineering process and the effect evaluation of hydraulic flushing.

To study the influence of hydraulic slotting inclination on the mechanical behaviors of coal seam during mining process, uniaxial compression experiments on coal specimens with a single pre-existing flaw inclined at 0°, 15°, 30°, 45°, 60°, 75°, 90° and intact specimens were conducted. Acoustic emission (AE) signals in the loading process were monitored, and fractal analysis method was introduced to investigate the AE characteristics. Additionally, the laboratory experiments were simulated by a finite element code. Both the experimental and numerical results show that the existence of a flaw reduces the mechanical properties of coal. The uniaxial compressive strength and modulus of elasticity increase polynomially and linearly with the increase of inclination angle, respectively. When the coal specimen ruptures finally, the fewer the surface secondary cracks or the more the sudden drops of stress, the smaller the peak value of AE count. According to the stress–strain curve, the loading process is divided into five stages: (I) compaction stage; (II) linear elastic stage; (III) stable crack propagation stage; (IV) accelerating crack propagation stage; (V) post peak and residual stage. AE fractal characteristics in various stages of each specimen were determined by Grassberger and Procaccia algorithm based on phase space reconstruction theory. AE count show fractal characteristics from stage III. The fractal dimension declines rapidly in stage IV, and continues to decline further or rise slightly in stage V, but both are lower than that in stage III. Therefore, the changing rule of AE fractal dimension in different loading stages can be used as a precursor to coal and rock dynamic disasters.

In terms of coal’s stability and failure, soaking time and water content play a significant role in geotechnical engineering practice. To determine the soaking time effect on the mechanical behavior of coal samples and the response of AE (acoustic emission) signal throughout loading, the samples with different soaking times (0–120 hours (h)) were prepared and tested under uniaxial compression. AE signals were continuously monitored during loading to examine the AE characteristic response via the AEwin Express-8.0 system. The results revealed that the mechanical characteristics of the coal samples decreased with an increase in soaking time. When coal samples were subjected to uniaxial compression, AE events occurred due to the formation of the cracks, which further propagated to cause coal fracture. AE counts and the accumulative counts fluctuated with time and corresponded very well to the load. Therefore, AE counts and the trend of the accumulative counts of AE qualitatively explained the rupture of the coal under stress. In addition, the variation in trends of AE counts, AE accumulative counts, and load with time at various phases of all samples were obtained. It is concluded that AE counts increase suddenly during a slow increase phase and peak at the active increase phase. During the attenuation phase, the AE counts first decrease significantly with stress drop, but also a slight increase was observed due to the initiation of secondary cracks. These research results are of great significance as a precursor in coal and rock failure.

Although rechargeable aqueous zinc batteries (RAZB) have experienced their renaissance recently, Zn-metal anodes still suffer from serious dendrites growth and inevitable Zn corrosion in mild aqueous electrolyte during cycling. It is imperative to provide a simple and effective strategy to address the above problems. Herein, we have developed a one-step strategy to in-situ fabricate a homogeneous and stable protective layer composing of dense ZnF2 and embedded Cu particles on the electrode at room temperature. The ZnF2-Cu protective layer with both high Zn2+ transfer number (0.758) and homogeneous nucleation sites (Cu particles) with excellent zinc affinity exhibits remarkable synergistic effect for dual purpose: 1) to effectively inhibit severe dendrites growth via regulating Zn nucleation and 2) to suppress Zn corrosion and the accompanying hydrogen evolution by preventing Zn metal surface from aqueous electrolyte attacking. As a result, the ZnF2-Cu@Zn anodes can maintain stable cycling for>1600 h with super low over-potential and increased average coulombic efficiency (CE). In addition, the ZnF2-Cu@Zn || V2O5 full cells provide a reversible capacity of 103 mA h g−1 after 2000 cycles at an ultra-high current density of 10 A g−1. This work proposes a promising approach for the practical application of RAZB in the future.

During the process of cross-cut coal uncovering, the stress and gas pressure of the coal mass change with time and even lead to coal and gas outburst. This paper establishes a coupled model that includes the equation of coal deformation, gas diffusion , gas seepage and permeability evolution based on the dual poroelastic theory. This model is applied into COMSOL Multiphysics numerical software. The distribution and evolution of the stress and gas pressure in front of the working face can be obtained from the numerical results. The stepped increase mechanism of the combined potential energy in the tunneling process is proposed, which is used to analyze the evolution of elastic potential energy and gas potential energy. The results can be summarized as follows: under natural conditions, an obvious abnormal stress area occurs near the fault, and the stress of the coal seam is greater than that of the rock stratum. Under tunneling conditions, a original stress (OS), stress concentration (SC) and stress reduction (SR) are formed successively in the front of the working face. And correspondingly, the gas accumulates in SC due to the closure of cracks. The distributions of gas pressure p f and p m are approximately the same during tunneling, and they can reach an equilibrium state after 300 days. The coupled effects of stress and gas pressure gradually intensify, so the elastic potential energy and the gas potential energy of the coal continuously accumulate. The combined potential energy of coal increases with tunneling length, and an outburst is very likely to occur when the combined energy exceeds the surface energy of the coal body at the “Key point”. This research is helpful to understand the evolution mechanism of stress and gas pressure of coal seam in the process of cross-cut coal uncovering, and to know the effects of it to the dynamic disaster.

Coal dust explosion tests were performed in a 20-L spherical vessel and the post-explosion dust samples were collected for analysis. Various characteristic parameters of each explosion trial were r...

Fabricating sulfur host for the cathode with strong confinement effect and high dispersion of sulfur is vitally important to the development of high-performance lithium sulfur batteries. Benefiting from their unique and tunable structure, good conductivity and chemical inertness, hollow porous carbon materials has been considered as a promising candidate. Herein, precisely designed waxberry-like hierarchical hollow carbon spheres (h-CNS) have been synthesized as the sulfur micro-containers for lithium sulfur batteries. The prepared h-CNS/S electrode shows a good rate capability of 1311 mAh g-1at 0.1 C and 962 mAh g-1at 1 C. In addition, the h-CNS/S electrode also shows satisfactory long cycle performance with 622 mAh g-1at 0.5 C and 400 mAh g-1at 4 C over 600 cycles. The desirable performance can be attributed to the wedge-shape micro-containers which improve the high dispersion of sulfur inside the channels and inhibit the loss of intermediate polysulfide. Moreover, the unique structure can also enhance the transfer of both lithium ions and electrons which benefits to the rate capability of the lithium sulfur batteries.

The temporal evolution of aerosolized SiO 2 nanoparticles (NPs) released into an environmental test chamber has been investigated to interrogate the effect of relative humidity (RH) on the deposition and coagulation of the nanoparticles. The size-resolved deposition rate and Brownian coagulation coefficient for the particles at RH of ~ 10%, 27%, 40%, 54%, and 64% are estimated. The results show that the effect of RH on the deposition rate is size-dependent; for particle diameter (Dp) 70 nm, it grows as the RH rises. Generally, both low and high RH tends to enhance the deposition rate, and the minimum rate appears at moderate RH (~ 54%). Electrostatic repulsion is probable for the inter-particles interaction at the low RH while the surface roughness due to water molecular adsorption is a main reason for the particle-wall interaction at higher RH. The increasing coagulation coefficient at high humidity correlates to the strong inter-particle adhesion, which may be caused by the water molecular adsorption on the hydrophilic surfaces of the SiO 2 NPs due to the formation of nanometer-thick water film. This study suggests that air humidity plays unignorable roles in particle deposition and coagulation.

Reference materials (RM)-assisted Rayleigh-Gans-Debye approximation (rm-RGDA) has been developed and used to in situ determine the size and thickness of the adlayer on the particles in solution. The particle size determined by rm-RGDA is quite close to that measured by electron microscopy but significantly smaller than that measured by DLS. The BSA adlayer absorbed on PS50, PS100 and SiO2 NPs is 3.3, 0.9 and 1.2 nm, respectively, and close to those observed by SEM, which is 4.6, 1.3 and 3.8 nm, respectively. The FTIR analysis results show that the BSA absorbed on larger particles or hydroxyl-abundant surface, e.g. PS100 and SiO2 NPs can lose its secondary structure, e.g. α-helix, to a great extent and that absorbed on a more curve surface, e.g. smaller PS50 particles can largely preserve its secondary structure as its free state. The measurement results show the curvature of the NPs is closely related to the structure change of the adsorbed protein. This method provide a facile and new approach to measure the size and its adlayer change of the hybrid and core-shell structured nanoparticles in a wide range of wavelength.SIGNIFICANCEQuantitative study on the adsorption of the protein on colloidal nanoparticles is an important approach to understand the biophysical effect, compared with other ex situ methods such as TEM and SEM, where the specimen are undergone pre-processing and no longer the original state in measurement. It is, therefore, a big challenge. In order to cope with this challenge, UV-vis based RGDA has been developed and applied to in situ measure the size of the dispersed colloidal nanoparticles and their protein adlayer thickness, where the protein adlayer thickness on the colloidal nanoparticles can be easily determined. We believe this method provide a facile and sensitive way to in situ measure the dimension change of hybrid colloidal nanoparticles.

In order to study the mechanics and acoustic emission (AE) characteristics of fractured rock under water-rock interaction, dried and saturated sandstone samples with prefabricated double parallel cracks were prepared. Then, uniaxial compression experiments were performed to obtain their AE signals and crack propagation images. The results show that water reduces the strength and fracture toughness of fractured sandstone and enhances plasticity. After saturation, the samples start to crack earlier, the cracks grow slowly, the failure mode is transformed from shear failure along the prefabricated cracks to combined shear and tensile failure, more secondary cracks are produced. The saturated samples release less elastic energy and weaker AE signals in the whole failure process. However, their AE precursor information is more obvious and advanced, and their AE sources are more widely distributed. Compared with dry specimens, the AE frequencies of saturated specimens in the early stage of loading are distributed in a lower frequency domain. Besides, the saturated samples release less complex AE signals which are dominated by small-scale signals with weaker multi-fractal characteristics. After discussion and analysis, it is pointed out that this may be because water makes rock prone to inter-granular fracture rather than trans-granular fracture. The water lubrication also may reduce the amplitude of middle-frequency band signals produced by the friction on the fracture surface. Multi-fractal parameters can provide more abundant precursory information for rock fracture. This is of great significance to the stability of water-bearing fractured rock mass and its monitoring, and is conducive to the safe exploitation of deep energy.

For bimetallic nanoparticles (NPs), the degree of alloying is beginning to be recognized as a significant factor affecting the NP properties. Here, we report an alloyed crystalline Au-Ag hollow nanostructure that exhibits a high catalytic performance, as well as structural and chemical stability. The Au-Ag alloyed hollow and porous nanoshell structures (HPNSs) with different morphologies and subnanoscale crystalline structures were synthesized by adjusting the size of the sacrificial Ag NPs via a galvanic replacement reaction. The catalytic activities of the nanomaterials were evaluated by the model reaction of the catalytic reduction of p-nitrophenol by NaBH4 to p-aminophenol. The experimental results show that the subnanoscale crystalline structure of the Au-Ag bimetallic HPNSs has much greater significance than the apparent morphology does in determining the catalytic ability of the nanostructures. The Au-Ag alloyed HPNSs with better surface crystalline alloying microstructures and open morphologies were found to exhibit much higher catalytic reaction rates and better cyclic usage efficiencies, probably because of the better dispersion of active Au atoms within these materials. These galvanic replacement-synthesized alloyed Au-Ag HPNSs, fabricated by a facile method that avoids Ag degradation, have potential applications in catalysis, nanomedicine (especially in drug/gene delivery and cancer theranostics), and biosensing.

Current coal seams in China are characterized by great depth, low permeability, and strong adsorption features, and thus, the extraction of methane is relatively difficult and gas disaster remains serious. To overcome this limitation, the hydraulic flushing and hydraulic slotting are adopted to improve the permeability of coal seams. A 2D model of gas seepage was established by using the solid mechanics and darcy module in Comsol Multiphysics, version 4.3b. The factors influencing pressure relief, such as the radius of borehole after hydraulic flushing, the initial gas pressure, and the permeability of coal seam, were studied. The coupling effects of these three factors on the effective influence radius were studied through the response surface methodology, and a quadratic polynomial equation between effective influence radius and three factors was derived. The results showed that Gas pressure distribution (e.g. gas full emission region, gas pressure transition region and original gas region) near the borehole, corresponded well with stress distribution (stress relief zone, stress concentrating range and original stress zone). The plastic zone formed around the borehole leaded to stress reduction, and the increasing porosity and permeability resulted in pressure decline. The effective influence radius increased with the borehole radius and the initial permeability, but decreased with original gas pressure. Besides, it was found that an increase in one factor would restrict the role of other two factors on the effective influence radius. This study is helpful to choose the most suitable parameters to achieve high extraction efficiency and lower gas content/pressure.

In order to study the effect of water on the electromagnetic radiation (EMR) signals released during rock deformation and fracturing, uniaxial compression experiments were performed on sandstone samples with different water contents. During the experiments, the EMR signals were acquired. Furthermore, the time-frequency characteristics of the signals were analyzed, and their generation mechanism and the effect of water were discussed in depth. The results show that the EMR energy released decreases gradually with the increase of water content, and the EMR energy and water content can be linked by a binomial equation. For sandstone with higher water content, the precursor characteristics of EMR released in the fracturing process are more obvious. With the increase of water content, the proportion of signals in the low frequency band grows gradually, while that of signals in high frequency band falls gradually. Water reduces the macroscopic mechanical strength and fracture mechanical characteristics of sandstone, which weakens the EMR signals produced by piezoelectric effect and charge separation. Besides, with respect to the microscopic fracturing mode, the sandstone with higher water content is more likely to undergo inter-granular fracturing, which may be an important microscopic reason for the weakening of EMR of water-bearing sandstone. An EMR-based damage evolution model of water-bearing sandstone was preliminarily established, and the model helps to calculate the stress state of water-bearing rock.

The acoustic emission (AE) and ultrasonic (UT) simultaneous monitoring program is designed using concrete samples under step loading. The time-varying response characteristics of AE-UT are studied and the cross-correlation analysis between AE-UT parameters is obtained. Moreover, the joint response of UT-AE spatial distribution field is analyzed, and an AE-UT joint monitoring method to detect early-warning signals of a rockburst disaster in a coal seam is proposed. The results show the following. (1) During the loading process, the AE pulses/energy and UT attenuation coefficient first slowly decrease and then increase steadily and finally rapidly increase, while the UT velocity shows a trend of first gradually increasing and then slowly decreasing and finally a sharp decline. (2) AE pulses and energy are significantly or highly correlated with the UT velocity and attenuation coefficient. The AE energy and UT attenuation coefficient can better characterize the damage evolution of concrete under step loading. (3) The UT field evolves ahead of the rupture on the surface, and the long/narrow strip distribution region of UT parameters is consistent with the future failure zone; meanwhile, the AE events can visually reflect the evolution path of internal damage as well as the dynamic migration mechanism of UT field.

The research of pentacene thin-film transistors (TFTs) and pentacene single crystal has been the research focus recently. In this paper, we have performed both experimental and theoretical studies for the influence of morphology of the first pentacene layer on the electronic properties of TFTs. We proposed a two-dimensional grain boundary model to interpret the relationship of the mobility as well as threshold voltage shift under gate bias-stress and the first-layered grain size. We obtained several meaningful parameters, such as mobility in single grain, trap density in grain boundary and the height of potential barrier. This is meaningful to optimize the performance of organic thin-film transistors. Meanwhile, we raised a new strategy to prepare pentacene single crystal, which starts from pentacene monolayer film and the process can be defined as two step growth of high quality, large pentacene single crystals. We systematically studied the molecular dynamics in this process, which may make essential preparation for device fabrication in the future.

A two-step growth method, namely, initial crystallization from pentacene monolayer grains to nanosized single crystals (nanocrystals) and subsequent physical vapor transport (PVT) growth on the nanocrystals as seeds, is demonstrated to fabricate larger microsized pentacene single crystals. The pentacene monolayer film deposited on a bare SiO2 substrate was found to self-assemble to nanoparticles during a post-annealing process. Selected area electron difffraction demonstrates unambiguously the nanoparticles and the microsized particles grown by the following PVT are both single crystals but with different crystal phases. Such a two-step growth technology maintains the intrinsic interface states between the SiO2 dielectric and the pentacene active layer and provides a more flexible way to in-situ prepare oraganic single crystals for device fabrication. The detailed investigation of morphology evolution and the discussion of formation mechanism of nanocrystal seeds indicate that the pentacene molecular tran...

The charge transport process in organic thin-film transistors (OTFTs) has always been under intensive research while the mechanism is still controversial, even in the small-molecule OTFTs. In this study, we report on a transport model for interpreting the charge transport mechanism in polycrystalline pentacene TFTs. By investigating the growth mode of pentacene films and the distribution of charge carriers in the channel of OTFTs, a transport model involving two-dimensional single-layered grains and grain boundaries (GBs), namely the two-dimensional grain boundary (TDGB) model, is proposed for describing the charge transport process in polycrystalline pentacene TFTs. An analytical expression for the field-effect mobility could be obtained from the model. The model is applied to explain the mobility dependence on the grain sizes at the first monolayer of pentacene films, temperature and on gate voltage in polycrystalline pentacene TFTs, with good agreement obtained. In addition, the values of some crucial ...

The poor light emission efficiency in silicon prevents its wide application in the field of optoelectronics. Tailoring silicon into direct band-gap semiconductor, will not only vigorously promote the development of silicon-based optoelectronic integrated circuits, but also make significant achievements in the field of solid-state light sources and solar cells. This article explores the nature of the electronic states of the direct band-gap H-passivated silicon nanonets and discusses the mechanism of the band-edge momentum matrix enhancement by means of first-principles calculation. A well corresponding relationship between the band-edge levels of bulk-like silicon and silicon nanonet is established. The first several conduction bands of silicon nanonets have the characteristic of folding energy levels, but the quantum confinement effect induces larger enhancement in momentum matrix elements than those of traditional silicon nanostructures. Two nano-fabrication techniques are proposed to produce the nanonet structure, as is expected to be widely applied in optoelectronic integrated circuits.

In order to explore the causes of acoustic emission (AE) signals during coal failure, the coal samples with original joints were subjected to uniaxial compression experiments, and the AE signals were monitored by AEwin Test for Express-8.0. Based on the multifractal theory, the multifractal characteristics of AE were analyzed. The results showed that the AE counts and accumulative counts change over time corresponded well with the load-time, which reflected the degree of crack evolution and loading. During the initial loading stage, the cracks expanded gradually along the trace of the original cracks, which could induce a few AE events, while with the increase of load, the cracks enlarged gradually and then joined together to form a macroscopic fracture, which would cause much more AE events within a larger value. Multifractal spectrum [[Formula: see text]] of AE was more concentrated in the right side, illustrating that the frequency of small signals was greater than that of the large signals in AE sequences, which revealed cracks expanding and microfracture events dominated during the loading process. The greater the multifractal spectrum width ([Formula: see text] was, the larger the AE signals differences were, which reflected that AE varied more intensely. The more developed the original cracks, the more obvious the multifractal characteristics. This research revealed the causes and percentage of the AE events within small or large signals, which would help us to recognize crack evolution of coal and generation mechanism of AE.

We report on the fabrication of an organic field-effect transistor (OFET) of a monolayer pentacene thin film with top-contact electrodes for the aim of ammonia (NH3) gas detection by monitoring changes in its drain current. A top-contact configuration, in which source and drain electrodes on a flexible stamp [poly(dimethylsiloxane)] were directly contacted with the monolayer pentacene film, was applied to maintain pentacene arrangement ordering and enhance the monolayer OFET detection performance. After exposure to NH3 gas, the carrier mobility at the monolayer OFET channel decreased down to one-third of its original value, leading to a several orders of magnitude decrease in the drain current, which tremendously enhanced the gas detection sensitivity. This sensitivity enhancement to a limit of the 10 ppm level was attributed to an increase of charge trapping in the carrier channel, and the amount of trapped states was experimentally evaluated by the threshold voltage shift induced by the absorbed NH3 molecular analyte. In contrast, a conventional device with a 50-nm-thick pentacene layer displayed much higher mobility but lower response to NH3 gas, arising from the impediment of analyte penetrating into the conductive channel, owing to the thick pentacene film.

A net-like nanostructure of silicon named silicon nanonet was designed and oxygen atoms were used to passivate the dangling bonds. First-principles calculation based on density functional theory with the generalized gradient approximation (GGA) were carried out to investigate the energy band gap structure of this special structure. The calculation results show that the indirect–direct band gap transition occurs when the nanonets are properly designed. This band gap transition is dominated by the passivation bonds, porosities as well as pore array distributions. It is also proved that Si–O–Si is an effective passivation bond which can change the band gap structure of the nanonets. These results provide another way to achieve a practical silicon-based light source.

Threshold voltage shift under applied gate voltage is a key factor characterizing stability of organic thin-film transistors (OTFTs), while the physical mechanism is still controversial. In this study, we systematically examined the initial growth of pentacene polycrystalline films under different growth rates. Bias stress performance of the fabricated pentacene-based OTFTs was found to be highly related to the initial gain size of the pentacene films. Larger grain size at the first deposition layer led to smaller threshold voltage shift. The quantitative correlation can be described by a two-dimensional microscopic mobility model relating to the grains and grain boundaries.

Pentacene thin film deposition with high uniformity of 2.7% on flexible polyethylene terephthalate (PET) substrate is achievable over area of 300 mm× 500 mm using a simple roller vacuum thermal evaporation system with point sources. Thickness numerical simulations, agree well with measurements, indicate that the multi-dimensional movement of the cylindrical sample holder guarantees film uniformity over a larger area. High device performance with excellent uniformity and reproducibility is demonstrated by pentacene-based thin film transistor arrays on large PET substrates with average saturation mobilities of 0.42 cm2/V s. The system provides a feasible thin film deposition architecture for large-scale organic electronics.

A conventional vacuum thermal evaporation (VTE) system has been extended to a roller-VTE system with a moving substrate-holder to realize large-area organic film deposition. The multidimensional movement of the substrate-holder guarantees excellent uniformity of the large-area pentacene thin films. An 85-nm-thick pentacene film with a relative standard deviation as low as 2.7% is demonstrated within a 300 mm × 500 mm area. Thin film transistor arrays are then fabricated using the uniform pentacene films. The average transistor mobility is up to 0.85 cm2/V s with a relative standard deviation of 10%.

The effect of selenization and post-annealing treatment on the visible luminescence property of porous silicon has been investigated. Scanning electron microscopy and x-ray photon spectroscopy were employed to analyze the surface morphology and composition, respectively. Due to the passivation of Si–Se bonds on the surface, the photoluminescence intensity increases significantly with the increasing selenized temperature, and the photoluminescence stability is also improved after selenization. Furthermore, post-annealing of selenized porous silicon at appropriate temperature can enhance the photoluminescence behaviors.