Mobility Values Research Articles

Physically‐Deposited Hole Transporters in Perovskite PV: NiOx Improved with Li/Mg Doping

AbstractNickel oxide (NiOx) has received a lot of attention as an inorganic hole transport material (HTM) in perovskite solar cells (PSCs) during the last decade, owing to its high hole mobility, chemical stability, good optical transparency, and suitable energy levels that align with the valance band of the perovskite absorber methylammonium lead iodide (MAPbI3). This study explores Li and Mg co‐doped NiOx thin films physically‐deposited from developed sputtering targets obtained through cold isostatic pressing and sintering. After sputtering, the structural, elemental, morphological, optical, and electrical properties of the layers are investigated by XRD, XPS, SEM, AFM, UV–vis spectrophotometer, and Hall‐effect; revealing that crystalline, homogeneous, and smooth films are obtained. In particular, improvements in mobility and conductivity values are observed with Li and Mg doping, which contribute to enhanced PSC performance when used as an HTM layer in the glass‐indium tin oxide (ITO)/NiOx‐based HTM/MAPbI3/phenyl butryic acid methyl ester (PCBM)/bathocuproine (BCP)/Ag architecture. The champion solar cell achieves PCE of 15.52%. In addition, the average values of all samples are boosted, JSC (from 13.21 to 15.60 mA cm−2) and FF (from 59.32% to 67.7%), relative to pristine HTM, resulting in a pronounced PCE increment of up to 30% with the HTM film sputtered by a single target of co‐doped material.

Effect of cadmium chloride treatment on CdS buffer layer and its impact on growth of CdTe layer: An experimental and numerical studies

This paper focuses on the study of the structural, morphological, electrical and optical properties of the pristine and CdCl2 treated CdS buffer layer as well as of the CdTe thin films deposited on the pristine and CdCl2 treated CdS buffer layers. CdS buffer layers have been grown by Chemical bath deposition technique and CdTe absorber layers have been deposited by thermal evaporation method. These thin films have been characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Hall Effect measurements and UV–Vis spectroscopy. XRD analysis demonstrated that there is an increase in the intensities of peaks as well as crystallite size of the CdCl2 treated CdS buffer layer as well as of the CdTe thin films deposited on them. SEM analysis illustrated there is improvement in grain size and compactness of CdCl2 treated CdS buffer layer as well as that of the CdTe thin films deposited on them than that of the pristine samples. From the optical and electrical properties analysis it is observed that there is enhancement in absorbance and decrement in bandgaps with increased values of carrier concentration, mobility, and conductivity of the CdCl2 treated CdS buffer layer and the CdTe thin films deposited on the CdCl2 treated CdS buffer layer respectively. Finally, glass/FTO/CdS/CdTe and glass/FTO/CdS/CdCl2/CdTe solar cells were numerically simulated by SCAPS using the experimental data obtained in the present study to extract J-V curve and the influence of temperature and defect density on the J-V characteristics were also studied. The extracted parameters are Voc = 1.00V, Jsc = 30.41 m A/cm2, F·F. = 85.31% and ƞ = 25.94% of the glass/FTO/CdS/CdCl2/CdTe solar cell. Hence these solar cells can be fabricated experimentally as their suitability has been proved through numerically simulated results.

High Electrical Conductivity and Hole Transport in an Insightfully Engineered Columnar Liquid Crystal for Solution-Processable Nanoelectronics.

Discotic liquid crystals (DLCs) are widely acknowledged as a class of organic semiconductors that can harmonize charge carrier mobility and device processability through supramolecular self-assembly. In spite of circumventing such a major challenge in fabricating low-cost charge transport layers, DLC-based hole transport layers (HTLs) have remained elusive in modern organo-electronics. In this work, a minimalistic design strategy is envisioned to effectuate a cyanovinylene-integrated pyrene-based discotic liquid crystal (PY-DLC) with a room-temperature columnar hexagonal mesophase and narrow bandgap for efficient semiconducting behavior. Adequately combined photophysical, electrochemical, and theoretical studies investigate the structure-property relations, logically correlating them with efficient hole transport. With a low reorganization energy of 0.2eV, PY-DLC exhibits superior charge extraction ability from the contact electrodes at low values of applied voltage, achieving an electrical conductivity of 3.22 × 10-4 Sm-1, the highest reported value for any pristine DLC film in a vertical charge transport device. The columnar self-assembly, in conjunction with solution-processable self-healed films, results in commendably elevated values of hole mobility (≈10-3 cm2V-1s-1). This study provides an unprecedented constructive outlook toward the development of DLC semiconductors as practical HTLs in organic electronics.

Fast crystallization of InSe thin films via pulsed laser welding technique and effect of crystallinity on the optical and dielectric properties

In the current study the crystalline phase of indium selenide thin films which were grown by the thermal evaporation technique is achieved via pulsed laser welding technique (PLW) in a second. The films crystallinity is achieved under various welding conditions including the pulse width ( PW ), repetition frequency ( fr ) and pulse diameter ( d ). The optimum parameters for obtaining well crystalline phase are PW=1.0 ms, fr=10 Hz and d= 1.0 mm. PLW induced crystallinity showed preferred structure relating to monoclinic phase of InSe. Compositionally while amorphous films exhibited In2Se3 chemical structure, crystalline ones preferred InSe phase. Associated with this type of crystallinity, direct and indirect energy band gap values of 2.32 eV and 3.12 eV are determined. The crystalline films showed lower dielectric constant value accompanied with higher optical conductivity and higher terahertz cutoff frequency in the infrared range of light. In addition the dielectric dispersion spectra were treated using Drude–Lorentz model to read the optical conductivity parameters for the PLW assisted crystalline InSe terahertz resonators. The treatment showed that the crystallinity of the films resulted in improved free carrier density, longer relaxation times at femtosecond level, larger plasmon frequencies and higher drift mobility values. These features together with the response of terahertz cutoff frequency to IR excitations make crystalline InSe thin films promising for optoelectronic and terahertz technology applications.

Effect of wire diameter and extent of wire composite splint on the mobility of luxated and anchor primary teeth: A typodont study.

The recommendations for splinting are well established for the injuries of permanent dentition; however, ambiguity still exists for the injuries in primary dentition. Hence, this study aimed to determine the most appropriate dimensions of stainless steel wire and its extent, for achieving the physiologic mobility in primary dentition. This study was designed as an invitro experiment by using a typodont model of primary dentition. The baseline mobility of primary maxillary incisors was calibrated to the physiologic mobility of natural primary incisors by using a Teflon tape wrapped around the roots of resin teeth. Splinting was done using a stainless steel wire of 0.2 mm (Group I), 0.3 mm (Group II), and 0.4 mm (Group III). These groups were subdivided (a, b, and c) on the basis of the extent of the splint, and pre splint mobility (Pre-PV) and post-splint mobility (Post-PV) were tested by Periotest M. The splint effect was calculated by subtracting Post-PVs and Pre-PVs. The normal values of mobility in healthy human volunteers ranged from 10.5 to 13. The overall splint effect was higher in Group III irrespective of the extent of the splint, whereas it was found to be the lowest in Group I (b and c). The splint effect increased with the extent of the splint in all the groups. Among all the groups, the splint effect on the anchor teeth was observed to increase with the extent of the splint and the diameter of the wire. The mobility of the injured and anchor teeth splinted with 0.2-mm stainless steel wire was similar to the pre-splint and physiologic mobility. The most favorable extension was one tooth adjacent to the injured tooth on each side for both 0.2- and 0.3-mm wires.

Extracting charge carrier mobility in organic solar cells through space-charge-limited current measurements

Mobility is a critical parameter influencing the overall performance of organic solar cells (OSCs). Herein, we innovatively elucidated the intricate interrelation between the photovoltaic molecular structures and the methodologies employed for the extraction of charge carrier mobility in OSCs. We proposed a simple yet effective principle to accurately extract charge carrier mobility values using the standard space-charge-limited current (SCLC) measurement, while critically assessing theoretical and experimental deficiencies through the drift-diffusion analysis. It was found that field-dependent charge transport is necessitated to describe the prominent long-range intrachain hopping carrier behavior in polymers, while short-range intermolecular hopping results in trap-involved charge transport within small molecular acceptors. Based on the above understanding, a synergetic inter/intra-molecular hopping strategy was proposed to fabricate thick-film all-polymer OSCs, and an unprecedented power conversion efficiency (PCE) of 16.61 % was achieved in the 300 nm PM6:PY-IT OSC. This work not only presents a precise and straightforward approach for measuring mobility values, but also provides a significant reference about charge carrier transport to make optimal decisions regarding photovoltaic material design and device fabrication process of high-performance OSCs.

Predicting the therapeutic response to valproic acid in childhood absence epilepsy through electroencephalogram analysis using machine learning

Childhood absence epilepsy (CAE) is a common type of idiopathic generalized epilepsy, manifesting as daily multiple absence seizures. Although seizures in most patients can be adequately controlled with first-line antiseizure medication (ASM), approximately 25 % of patients respond poorly to first-line ASM. In addition, an accurate method for predicting first-line medication responsiveness is lacking. We used the quantitative electroencephalogram (QEEG) features of patients with CAE along with machine learning to predict the therapeutic effects of valproic acid in this population. We enrolled 25 patients with CAE from multiple medical centers. Twelve patients who required additional medication for seizure control or who were shifted to another ASM and 13 patients who achieved seizure freedom with valproic acid within 6 months served as the nonresponder and responder groups. Using machine learning, we analyzed the interictal background EEG data without epileptiform discharge before ASM. The following features were analyzed: EEG frequency bands, Hjorth parameters, detrended fluctuation analysis, Higuchi fractal dimension, Lempel–Ziv complexity (LZC), Petrosian fractal dimension, and sample entropy (SE). We applied leave-one-out cross-validation with support vector machine, K-nearest neighbor (KNN), random forest, decision tree, Ada boost, and extreme gradient boosting, and we tested the performance of these models. The responders had significantly higher alpha band power and lower delta band power than the nonresponders. The Hjorth mobility, LZC, and SE values in the temporal, parietal, and occipital lobes were higher in the responders than in the nonresponders. Hjorth complexity was higher in the nonresponders than in the responders in almost all the brain regions, except for the leads FP1 and FP2. Using KNN classification with theta band power in the temporal lobe yielded optimal performance, with sensitivity of 92.31 %, specificity of 76.92 %, accuracy of 84.62 %, and area under the curve of 88.46 %.We used various EEG features along with machine learning to accurately predict whether patients with CAE would respond to valproic acid. Our method could provide valuable assistance for pediatric neurologists in selecting suitable ASM.

Stop Blaming Hopping Conduction in Nanocrystal Arrays, Use it for Active Photonics!

AbstractNanocrystals (NCs) are now established building blocks for photonic applications. However, their integration for optoelectronics has not yet reached the same level of maturity, in part due to the perceived bottleneck that is the inherent limited mobility resulting from hopping conduction. Significant efforts are made to improve this mobility, notably by tuning the particle surface chemistry to enable larger interparticle electronic coupling, and values of mobility of ≈10 cm2 V−1 s−1 have been achieved. It is acknowledged that this value remains significantly lower than those obtained in 2D electron gases but is on par with the mobility reported for vertical transport in epitaxially grown heterostructures with similar confinement energies. Since there appears to be limited perspectives for further increasing mobility values, a suggestion is made that efforts should instead be directed toward exploring the potential benefits offered by hopping conduction. One of these benefits is the bias dependence of the diffusion length, which plays a key role in designing bias‐reconfigurable optical responses for NC‐based devices. Some recent achievements in building bias‐activated devices will be reviewed and the essential criteria for designing future structures will be discussed. Ultimately, hopping conduction is an opportunity to generate new functionalities that low‐disorder materials would be unable to provide.

Development of a value-based scoring system for the MobQoL-7D: a novel tool for measuring quality-adjusted life years in the context of mobility impairment

Purpose To create a preference-based value set scoring system for the MobQoL-7D outcome measure, and to examine differences in the health state preferences of the general population and individuals with impaired mobility. Methods and materials A preference elicitation study was undertaken to ascribe utility weights to all health states (i.e., all unique combination of answers) described by the MobQoL-7D. The elicitation exercise was developed using the Online Elicitation of Personal Utility Functions (OPUF) tool. Two UK sample groups were recruited; firstly a representative general population sample (N = 504), secondly a balanced sample of individuals with impaired mobility (N = 368). Distinct preference-based value sets were developed for each sample. Differences in dimension ranking, weighting, and overall utility values were assessed. Results The general population sample considered most health states, especially the more severe states, to be worse than the mobility impaired sample comparatively. Statistically significant differences between the samples were observed in four of the seven MobQoL-7D dimensions. Conclusions This study is the first to provide preference-based value sets for the MobQoL-7D, ready for use in economic evaluations, QALY calculation, and other clinical or research applications. The study demonstrates how the general public and individuals with impaired mobility value health states differently.

Cross-linkable fluorene-based hole transporting materials for perovskite solar cells

Cross-linkable hole transporting materials (HTMs) based on fluorene core containing vinyl groups were synthesized and analyzed. It has been demonstrated that these HTMs are cross-linkable at temperatures above 200 °C and they are thermally stable at up to 400 °C. Cross-linking has little effect on energy level (HOMO) and causes only slight changes in the hole drift mobility values at room temperature, due to changes in spatial and energetic disorder. While employing cross-linked fluorene-diphenylamine derivative (V1145) as an HTM layer between perovskite and indium-tin oxide (ITO) in inverted perovskite solar cells (PSCs), the power conversion efficiency (PCE) of the cell was 11.42% (under AM 1.5G 100 mW cm−2 illumination), demonstrating the potential of the presented class of dopant-free organic HTMs.

Si(gh)ting the City: An Uber View of Calcutta

In this article, I take a socio-material approach to highlight the changes in the legibility of the built environment due to digital interfacing and the subsequent fragmentation of urban space. Using Uber as an example, I demonstrate how app-reliant mobility practices, reflexive of the changing mobility values in the city of Calcutta, manifest certain “temporal spaces”—quasi-virtual spaces of the online/digital-offline/material continuum—that imbricate the physicality of the city with the digital traces that Uber accrues about a particular location and the data about the rhythms of the individual users within that space. The investigation uses screenshots of Uber pick-up points to conceptualize legibility in the context of temporal spaces and how this changing legibility alters the kinaesthetic quality of Calcutta. Siting the argument in postrepresentationalist thought—one that does not assume an ontological distinction between representations and the referent—this article offers a posthumanist account of spatial performativity that considers the everyday entanglements of human actors, social practices, networked technologies, algorithms, and interfaces that render “legible” the urban space.

Construction of Mobile Internet Value Proposition Model: An Empirical Study Based on Cases and Structural Equation Modeling(SEM)

The pervasive influence of mobile internet is fundamentally reshaping both professional and everyday life, resulting in significant alterations to customer value creation models. Grounded in an extensive literature review, this article employs a causal case study methodology, incorporating in-depth interviews with 57 Chinese mobile internet users, along with observational data. The study aims at illuminate the core essence of mobile internet value propositions, proposing a comprehensive measurement model for assessing these propositions. The empirical validation of this model is achieved through exploratory factor analysis of 87 preliminary questionnaires and confirmatory factor analysis of 902 final questionnaires. This empirical inquiry culminates in the development of a model delineating mobile internet value propositions, which encompasses the following key dimensions: ubiquity (accessibility anytime, anywhere, accommodating fragmented time), convenience (quick access, handy availability, easy operation), individualization (automatic recognition, personalized services, security), and localization (location-based, sending location, and acquiring location).

The relationship between trunk control, spinal posture, and spinal mobility in patients with multiple sclerosis: a cross-sectional study.

Trunk control, which plays a key role in balance and mobility, decreases in patients with multiple sclerosis (PwMS) and many parameters such as sensory, motor, and musculoskeletal systems affect trunk control. The aim of this study was to compare trunk control, spinal mobility, and spinal posture in PwMS with healthy controls and investigate the relationship between trunk control with spinal posture and spinal mobility in PwMS. The study was completed with 38 PwMS and 38 healthy controls with matched age and sex. Trunk control was evaluated with the Trunk Impairment Scale (TIS). Spinal posture and mobility were evaluated in sagittal and frontal planes using an IDIAG M360 Spinal Mouse. Spinal posture was evaluated in upright, maximum flexion, extension, left and right lateral flexion positions, and spinal mobility was evaluated from upright to flexion, extension, right and left flexion positions in sagittal and frontal planes. TIS scores, thoracic mobility angles (from upright to flexion and left lateral flexion), lumbar mobility angles (from upright to extension and right lateral flexion) and lumbar posture angle (maximum right lateral flexion) were lower, and thoracic posture angles (upright and maximum extension) were higher in PwMS than healthy controls (p < 0.05). No significant difference was found between other spinal postures and mobility values. In addition, there was only a negative relationship between thoracic spinal mobility from upright to extension and trunk control in PwMS (r = -0.349; p = 0.032). These findings indicate the importance of early detection of trunk disturbances in PwMS. Thus, even in the early stages of multiple sclerosis, detailed trunk assessment will guide the implementation of comprehensive exercise programs.

Editor's Message to Special Issue of Intelligent Transportation Systems and Pervasive Systems that Recreate the Value of Physical Mobility

Editor's Message to Special Issue of Intelligent Transportation Systems and Pervasive Systems that Recreate the Value of Physical Mobility

Determining ion mobility in perovskite films using the running fringes method

This study provides theoretical and experimental evidence that the voltage generated in perovskite films by interference fringes' motion at low velocities can be used as a tool for assessing ions' electric mobility in these materials. We introduce a theoretical model for running fringe (RF) photo-electromotive force (EMF) in bipolar semiconductors, which considers the effects of mobile ions. This model leads to an analytical expression for the dispersion relation of space charge waves in the presence of mobile ions. Notably, it predicts a peak in the RF photo-EMF voltage when the velocity of fringe displacement matches the ion velocity in the photo-induced space charge field. To validate this, we conducted RF photo-EMF measurements on thin films of the methylammonium lead iodide semiconductor. The observed experimental dependencies align closely with theoretical predictions, and the determined values of ions' electric mobilities and activation energies are consistent with those previously reported in the literature.

Entropy engineering enabled atomically dispersed Cu doping leading to an exceptionally high thermoelectric figure of merit in n-type lead chalcogenides

Entropy engineering fully dissolved extra Cu atoms into the interstitial lattice sites of lead chalcogenides, yielding high charge carrier mobility and ZT values in a wide temperature range.

In-depth theoretical analysis of the influence of an external electric field on charge transport parameters.

It is important to develop materials with environmental stability and long device shelf life for use in organic field-effect transistors (OFETs). The microscopic, molecular-level nature of the organic layer in OFETs is not yet well understood. The stability of geometric and electronic structures and the regulation of the external electric field (EEF) on the charge transport properties of four typical homogeneous organic semiconductors (OSCs) were investigated by density functional theory (DFT). The results showed that under the EEF, the structural changes in single-bond linked oligomers were more sensitive and complex than those of condensed molecules, and there were non-monotonic changes in their reorganization energy (λ) during charge transport under an EEF consisting of decreases and then increases (Series D). The change in λ under an EEF can be preliminarily and qualitatively determined by the change in the frontier molecular orbitals (FMOs) - the number of C-atoms with nonbonding characteristics. For single-bonded molecules, the transfer integral is basically unchanged under a low EEF, but it will greatly change at a high EEF. Because the structure and properties of the molecule will greatly change under different EEFs, the effect of an EEF should be fully considered when determining the intrinsic mobility of OSCs, which could cause a deviation 0.3-20 times in mobility. According to detailed calculations, one heterogeneous oligomer, TH-BTz, was designed. Its λ can be greatly reduced under an EEF, and the change in the energy level of FMOs can be adjusted to different degrees. This study provides a reasonable idea for verification of the experimental mobility value and also provides guidance for the directional design of stable high-mobility OSCs.

Carrier transport in bulk and two-dimensional Zn2(V,Nb,Ta)N3 ternary nitrides.

Density functional theory-based simulations are applied to study the electronic structures, carrier masses, carrier mobility and carrier relaxation times in bulk and two-dimensional (2D) Zn2(V,Nb,Ta)N3 ternary nitrides. Bulk Zn2(V,Nb,Ta)N3 possess moderate band gap sizes of 2.17 eV, 3.11 eV, and 3.40 eV, respectively. Two-dimensional Zn2(V,Nb,Ta)N3 have slightly higher band gap sizes of 2.77 eV, 3.33 eV, and 3.23 eV, respectively. Carrier mass, carrier mobility and carrier relaxation time are found to be anisotropic in all the studied structures. Bulk and 2D samples show an order of magnitude higher electron mobility compared to hole mobility. The highest electron mobility in bulk Zn2NbN3 and Zn2TaN3 is about ∼103 cm2 V-1 s-1. Importantly, for 2D Zn2NbN3, an abnormally high electron mobility of 1.67 × 104 cm2 V-1 s-1 is observed, which is not inferior to the highest known electron mobility values in 2D materials. Such a high electron mobility in 2D Zn2NbN3 can be attributed to a strong delocalization of the conduction band minimum, which is responsible for electron transport. Therefore, this work opens up new materials for high performance nanodevices, such as tandem solar cells and field-effect transistors. This study also provides deep physical insights into the nature of carrier transport mechanisms in bulk and 2D Zn2(V,Nb,Ta)N3 ternary nitrides.

Normative Values of Weight Bearing Lunge Test among Non-Athlete Females - A Criterion Based Study

Background and Aim A significant amount of ankle dorsiflexion is required for the proper performance of functional tasks such as walking running ascending stairs getting out of a chair and squatting.Objective This study set out to determine the normative ankle mobility values for both sides in various musculoskeletal circumstances. Methodology This was a criterion-based study conducted among 400 non-athlete females enlisted from various colleges under Alvarsquos Education Foundation. The test was conducted at Alvarsquos College of Physiotherapy and Rehabilitation Centre Moodbidri Dakshina Kannada Karnataka. The subjects were asked to lunge and their measurements were noted using measuring tape. Results The average ankle dorsiflexion range during the weight bearing lunge test was 10.3 cm on the left and 11.1 cm on the right side. Conclusion The mean distance between dorsiflexion ranges in the weight-bearing lunge test was 11.1 cm for the right side and 10.3 cm for the left side.

THE CHEMICAL QUALITY EVALUATION OF SOME SOILS (CHERNOZEMS and LUVISOLS) FROM DOLJ COUNTY

Agricultural lands represent 79% of the surface of Dolj county and about 84% are used as arable crops. Depending on the culture system chosen, the physical and chemical quality of the soil can be affected in different ways. The chemical quality of some soils from Dolj county (Chernozems, Luvisols) was evaluated using several indicators (soil reaction, organic matter content, total nitrogen, mobile phosphorus and mobile potassium). On the depth of 0-50 cm, in both soils, 75% of the mobile phosphorus values were very low-low, respectively extremely low-low. Most of the studied Luvisols were characterized by low values of the mobile potassium content (50% in the topsoil and 63% on the 0-50cm depth, respectively). High correlation between PAL and KAL content was found in case of Luvisols (R2=0.908) and low in case of Chernozems (R2=0.300). High correlation in case of Luvisols may be due to the applied fertilizers.The values of the content of organic matter, total nitrogen, mobile phosphorus and mobile potassium were lower in the case of Luvisols compared to Chernozems and in most cases the values of the studied chemical indicators decrease with an increasing depth. According to the analyzed data, these soils have high potential for mineral ang organic fertiliser application.