Disorder Parameter Research Articles

Evaporative self-assembly of the binary mixture of soft colloids.

We have reported experimental studies on the self-assembly and degree of ordering of a binary mixture of soft colloids in monolayer deposits obtained by controlled evaporation. A sessile drop containing soft colloids is evaporated on a solid surface to achieve a loosely-packed two-dimensional deposit with a hexagonal arrangement. The soft microgel particles possess a hard core with a compliant corona, which plays a crucial role in retaining the crystallinity of the binary particle monolayer. The ordered arrangement of the binary mixture is observed even when the bulk diameter of one type of particle is 25% higher than the other, irrespective of their mixing ratio (1 : 3, 1 : 1, and 3 : 1). The microgel particles of both sizes are found to be homogeneously distributed throughout the deposit, completely suppressing the size-dependent particle segregation. Furthermore, in contrast to the self-assembly of bidisperse hard colloids, wherein the lattice distorts to accommodate particles of disparate sizes, in soft colloids, the particles deform at the interface to preserve the crystalline lattice. Moreover, unlike the gradual order-to-disorder transition observed in the deposits consisting of monodisperse microgel particles, the deposits of a binary mixture of microgels exhibit no noticeable trend. The areal disorder parameter, pair correlation function and the shape factor which quantifies the local ordering of particles in the deposit indicate the absence of a distinct order-to-disorder transition for the binary mixtures.

The impact of charge carrier relaxation, electron trapping and oxygen p-doping on the photocurrent transients of a conjugated polymer probed by the Time of Flight method

Most conjugated polymers have been considered so far to be primarily unipolar (hole or electron transporting) materials, even though there is no intrinsic reason why the mobility of holes and electrons should be different in organic semiconductors. We experimentally demonstrated by the Time of Flight method that a prototypical conjugated polymer, poly[2-methoxy-5-(2-ethylhexoxy)-1,4-p-phenylenevinylene], does not show any preference for the transport of electrons or holes, i.e. an ambipolar charge transport. Furthermore, the presence of traps and (unintentional) p-doping makes it difficult to address the intrinsic nature of the charge transport mechanism. However, by disentangling the dependence of the mobility from extrinsic factors, such as molecular oxygen, we were able to reveal a non-dispersive conduction for both holes and electrons. We also reveal a transition from trap-control to thermalization-control in the electrons’ charge transport mechanism. We used the Gaussian disorder model to analyze the experimental data, and we found that the positional disorder parameter is negligible for holes, and only the energetic disorder governs their charge transport, while the electrons’ conduction is governed by the interplay of both energetic and positional disorder.

Consideration of Clinician and Researcher Opinions on the Parameters of Nonsuicidal Self-Injury Disorder Diagnostic Criteria

Nonsuicidal self-injury (NSSI) disorder represents an opportunity to address the significant costs associated with NSSI; however, there is a need to resolve the uncertainty regarding specific parameters of the diagnostic criteria to ensure clinical utility. As such, to better understand the clinical applicability, and guide future research in this area, clinicians and researchers in the field of NSSI (n=112) completed an anonymous online survey assessing their opinions regarding several aspects of NSSI disorder. Results highlight that past-month NSSI was the most frequently endorsed timeframe required for a NSSI disorder diagnosis. There was support for the clinical usefulness of several specifiers and general consensus regarding exclusion criterion. Finally, Disruptive, Impulse-Control and Conduct Disorders was considered to be the most appropriate diagnostic category. Our findings suggest that requiring four days of NSSI in the past one-month may enhance the clinical utility of NSSI disorder. Results also offer guidance on additional aspects of the diagnostic criteria to better describe and conceptualize NSSI disorder for research and clinical applications.

Multicomponent pyrochlore solid solutions with uranium incorporation – A new perspective of materials design for nuclear applications

Multicomponent pyrochlore solid solutions with and without uranium incorporation were fabricated and their thermal-mechanical properties were characterized. Multicomponent pyrochlore solid solutions without uranium exhibit comparable thermal conductivity and higher mechanical strength compared to baseline single component rare-earth titanate pyrochlore (A2Ti2O7). Uranium incorporation reduces hardness as compared with single component compositions. High entropy pyrochlore with uranium displays the highest thermal conductivity within multicomponent pyrochlore solid solutions with significantly better mechanical properties than UO2. The measured thermal conductivity correlates well with A-site cation mixing entropy and a modified size disorder parameter, and thus the size disorder and mixing entropy could be good indicators for predicting thermal conductivity of multicomponent pyrochlore solid solutions. This work opens up the possibility of designing multicomponent oxide solid solutions by controlling their chemical disorder/mixing entropy to achieve acceptable thermal-mechanical properties, desired radiation and corrosion performance for potential nuclear waste form and inert matrix fuel applications.

Trace Element Levels in Serum Are Potentially Valuable Diagnostic Markers in Dogs.

Simple SummaryDetermining trace element concentrations in serum can provide useful information about some diseases. Furthermore, a single blood sample can nowadays be used to determine trace element profiles by multielement techniques such as inductively coupled plasma-mass spectrometry. Along with other routinely determined biochemical parameters, trace element profiles provide information about the pathogenesis, diagnosis, and prognosis of diseases, and enable evaluation of the suitability of trace element supplementation as an adjunct therapy. In this study, we evaluated the suitability of using trace element profiles, together with other routinely determined biochemical parameters, in dogs suffering different diseases, as diagnostic markers in routine clinical practice.The objective of this study was to obtain information about the role of trace element imbalance in the pathogenesis of certain diseases in dogs and to evaluate the suitability of trace element profiling as an additional tool in the diagnosis. Serum trace element concentrations (copper, molybdenum, selenium and zinc) were measured in a cohort of healthy (control) dogs (n = 42) and dogs affected by hepatic (n = 25), gastrointestinal (n = 24), inflammatory/infection (n = 24), and renal (n = 22) diseases. These data were analyzed together with data on basic biochemical parameters (alanine aminotransferase, alkaline phosphatase, blood urea nitrogen, creatinine, albumin, globulin, and glucose) by using chemometric techniques. The chemometric analysis revealed distinctive association patterns between trace elements and biochemical parameters for each clinical disorders. The findings provide clear evidence for the important role of trace elements in disease, particularly in relation to acute phase reactions, with serum copper providing an indirect measurement of ceruloplasmin (positive acute-phase protein) and serum selenium and zinc acting as negative acute phase reactants. Molybdenum may also be a suitable marker of incipient renal disease. Thus, the analysis of trace element profiles, by multielement techniques, in a single serum sample would be a valuable additional tool for the diagnosis of certain diseases.

Post-traumatic stress disorder (PTSD), anger and mental health of school students in Syria after nine years of conflict: a large-scale school-based study.

The Syrian crisis has entered its ninth year with many being affected by the war. This is the largest-scale study that aims to evaluate the psychological profile of secondary school students in Syria. This is a cross-sectional study in schools in Damascus, Syria. The surveys assessed working habits, smoking, war exposure, grades, socioeconomic status (SES), social support, health-related quality of life (HRQL), post-traumatic stress disorder (PTSD), problematic anger, and other parameters. This study included 1369 students of which 53% suffered from PTSD and 62% from problematic anger. Around 46% declared a fair or worse general health and 61% had moderate or severe mental health. Only 9.3% did not report exposure to any war-related variable. War exposure had an impact on PTSD, anger, and HRQL, but not on students' grades. Smoking, having consanguineous parents, and working did not have a clear association with grades or anger. Social support weakly reduced PTSD and anger scores. Interestingly, working was associatedwith lowerPTSD scores but was associated with a worse physical component of HRQL. This is the largest study on school students in Syria that reports the psychological ramifications of war. Although the direct effects of war could not be precisely described, the high burden of PTSD and anger distress was a strong reflection of the chronic mental distress.

The role of the gastrointestinal tract in the processes of intoxication and detoxification of the body

This review presents literature data on the role of the gastric tract in the processes of intoxication and detoxification of endoand exobiotics. The factors that promote the absorption and metabolism of toxic products in the gastrointestinal tract are described. The causes of intoxication and the mechanisms of two-phase detoxification with the participation of phase I enzymes of the biotransformation of xenobiotics in the intestine, in particular cytochrome P-450 isoenzymes, are described in detail. The predominance of the cytochrome P-450 isoenzyme CYP3A4 in the intestine was shown, and among the enzymes of phase II of biotransformation in the intestinal wall, the most important are UDP-glucuronyltransferase and sulfotransferase. The data on the ways of correction of intoxication with the use of a detoxification complex of dietary nutrition are presented. Clinical studies have shown that a specialized program provides antioxidant protection and the work of enzymes of the I and II stages of the metabolism of toxins, a decrease in the absorption and excretion of metabolic products, can significantly reduce the intoxication of the body, which is extremely necessary during the treatment and rehabilitation of diseases of the gastrointestinal tract and other organs and systems. rehabilitation of the body. It was found that the use of products of detox nutritional program LEOVIT DETOX led to a significant decrease in the concentration of urea and creatinine, which indicates an accelerated elimination of toxins and metabolic products formed in the body. A decrease in the concentration in the blood of the main enzymes characterizing the detoxification activity of the liver ALT, AST, GGT was also established.The aim of the study was to evaluate the detoxification effectiveness of the preventive nutrition Program and individual detoxification products LEOVIT DETOX, designed to affect all stages of Exo — and endobiotic metabolism.Materials and methods. Detoxification nutrition LEOVIT DETOX includes: specialized food product of dietary preventive nutrition “Complex nutrition program DETOX”, detoxifying jelly and bars — specialized food products of dietary preventive nutrition for detoxification of the body. The DETOX nutrition program is designed for 15 days and contains 30 products. The dynamics of biochemical parameters of liver and kidney function disorders (AST, ALT, GGT, urea, creatinine), blood lipid spectrum (by total cholesterol), fasting blood glucose level, and products of lipid peroxidation in blood serum were measured.Results. The use of specialized food products of dietary prophylactic nutrition “, a Comprehensive nutrition program DETOX” leads to a significant decrease in the concentration of urea and creatinine, AST, ALT, GGT, cholesterol, glucose, diene conjugate, ketodienes of CARBONYLS and increased total oxidative activity of blood serum were examined.Conclusion. The use of a specialized food product of dietary preventive nutrition “Complex nutrition program DETOX” provides effective detoxification of the body in diseases of the gastro-intestinal system.

Relationship between electron flux and electron complexity in a disordered Dirac comb

The transfer matrix method is used to calculate the electronic states of a finite chain of structurally disordered delta-function potentials. With the probability density for the electrons in the chain we calculate a complexity measure C for a continuous probability distribution, defined by a function of Shannon’s entropy H, as an order measure of the chain, and the inverse participation ratio, or disequilibrium D, as a measure of localization of electron states. C is minimal for a completely ordered and maximal for a completely disordered chain. It is used as an indicator for the electronic transport in disordered systems characterized by a disorder parameter W. We also compare C with the transmission coefficient, T, and the inverse participation ratio D. A statistical interpretation is formulated based on the relationship between the disorder in the delta-function potentials and the transmitted and reflected electron flux. Hence, we are able to interpret the behavior of C with the formation of localized Gaussian distribution of the transmitted and reflected electron current j for growing disorder W.

Optical measure of disorder: Why Urbach analysis works for amorphous silicon but fails for amorphous carbon

We investigate the basis for the Paradox where the Urbach-slope disorder parameter disagrees with the Raman width in amorphous diamond-like carbon (DLC) materials (lower Urbach-Eo yet greater Raman width). We examined the bandgap and Urbach-slope measurement issues. While significant errors are identified, ultimately these cannot resolve the Paradox. This resolution involves large changes in shape of DLC's absorption band resulting from large energy shifts. To solidify the understanding of band energy shifts, we examined their properties using a-Si:H, well known for its agreement between Raman and Urbach-slope disorder parameters. Using Tauc-Lorentz (T-L) dispersion functions, the Urbach method works for a-Si:H because small changes in shape occur, as measured by (i) peak position, (ii) peak width, (iii) peak amplitude, and (iv) and gap energies. Moreover, for a-Si:H, a 5th condition (v) there is no other feature below the principal band to interfere with its fall. All 5 of these conditions fail for DLCs. Because T-L dispersions accommodate asymmetry, we traced the Paradox to a steepening of the band shape as it pushes toward lower energy. This steepening is unrelated to disorder, but to a boundary value problem where energy cannot be negative. We conclude that Urbach analysis is invalid for DLC materials, but the T-L width is a good measure instead. We also examined another disorder measure, where π bonds should be considered as disorder relative to the σ bonds in an idealized “amorphous diamond” sp3 network: superconvergence can be used to quantify these π transitions. Finally, further molecular orbital calculations are needed to properly interpret the changes in T-L widths.

Changes in 3-month mineral and bone disorder patterns were associated with all-cause mortality in prevalent hemodialysis patients with secondary hyperparathyroidism

BackgroundThere is limited evidence on the association between short-term changes in mineral and bone disorder parameters and survival in maintenance hemodialysis patients.MethodsWe investigated the association between changing patterns of phosphorus, calcium and intact parathyroid hormone levels and all-cause mortality in hemodialysis patients with secondary hyperparathyroidism. Each parameter was divided into three categories (low [L], middle [M] and high [H]), and the changing patterns between two consecutive visits at 3-month intervals were categorized into nine groups (e.g., L-L and M-H). The middle category was defined as 4.0–7.0 mg/dL for phosphorous, 8.5–9.5 mg/dL for calcium and 200–500 pg/mL for intact parathyroid hormone. Adjusted incidence rates and rate ratios were analyzed by weighted Poisson regression models accounting for time-dependent exposures.ResultsFor phosphorus, shifts from low/high to middle category (L-M/H-M) were associated with a lower mortality compared with the L-L and H–H groups, whereas shifts from middle to low/high category (M-L/M-H) were associated with a higher mortality compared with the M-M group. For calcium, shifts from low/middle to high category (L–H/M-H) were associated with a higher mortality compared with the L-L and M-M groups, whereas shifts from high to middle category (H-M) were associated with a lower mortality compared with the H–H group. For intact parathyroid hormone, shifts from low to middle category (L-M) were associated with a lower mortality compared with the L-L group.ConclusionsChanges in the 3-month patterns of phosphorus and calcium toward the middle category were associated with lower mortality. Our study also suggests the importance of avoiding hypercalcemia.

Thermal properties of rung-disordered two-leg quantum spin ladders: Quantum Monte Carlo study.

A two-leg quenched random bond disordered antiferromagnetic spin-1/2 Heisenberg ladder system is investigated by means of stochastic series expansion quantum Monte Carlo (QMC) method. Thermal properties of the uniform and staggered susceptibilities, the structure factor, the specific heat, and the spin gap are calculated over a large number of random realizations in a wide range of disorder strength. According to our QMC simulation results, the considered system has a special temperature point at which the specific heat takes the same value regardless of the strength of the disorder. Moreover, the uniform susceptibility is shown to display the same character except for a small difference in the location of the special point. Finally, the spin gap values are found to decrease with increasing disorder parameter and the smallest gap value found in this study is well above the weak coupling limit of the clean case.

Effect of oviductal fluid on bull sperm functionality and fertility under non-capacitating and capacitating incubation conditions

This study investigated the effect of bovine oviductal fluid from late follicular (LF) and early luteal (EL) phases on bull sperm functionality under non-capacitating (NCAP) and capacitating (CAP) conditions. Frozen-thawed semen samples from five bulls were thawed and incubated (0, 1 or 2 h) in NCAP and CAP media supplemented with 1% bovine oviductal fluid (LF and EL groups) and in absence of fluid (C group). Motion parameters were assessed by CASA; sperm viability, acrosomal integrity and membrane lipid disorder parameters were evaluated by flow cytometry; and sperm DNA fragmentation was evaluated by the Comet assay. Finally, in vitro fertilization with sperm treated under CAP conditions was performed and further embryo culture results evaluated. In NCAP medium, addition of LF and EL fluid increased the total and progressive motility, and LF fluid improved the stability of sperm DNA. However, under CAP conditions addition of LF and EL fluid decreased some sperm motion parameters and some parameters of sperm DNA stability. Proportion of viable sperm cells with low lipid disorder was higher in NCAP than CAP medium and addition of LF fluid markedly increased the proportion of viable spermatozoa with high lipid disorder and acrosome alteration (spontaneous acrosome reaction). Under current conditions, incubation of bull sperm with oviductal fluid before insemination did not affect detrimentally the IVF results nor embryo development, being blastocyst rate similar between CAP-LF, CAP-EL and control groups. In conclusion, oviductal fluid positively influences sperm functionality and modulate in vitro capacitation.

Topological Anderson Insulator in Disordered Photonic Crystals.

Recent studies have revealed the counterintuitive possibility that increasing disorder can turn a topologically trivial insulator into a nontrivial insulator, called a topological Anderson insulator (TAI). Here, we propose and experimentally demonstrate a photonic TAI in a two-dimensional disordered gyromagnetic photonic crystal in the microwave regime. We directly observe the disorder-induced topological phase transition from a trivial insulator to a TAI with robust chiral edge states. We also demonstrate topological heterostructures that host edge states at interfaces between domains with different disorder parameters.

Kinetic Monte Carlo Study of Triplet-Triplet Annihilation in Conjugated Luminescent Materials

It is well known that in organic solids the collision of two excitons can give rise to delayed fluorescence (DF). Revived interest in this topic is stimulated by the current endeavor towards the development of efficient organic optoelectronic devices such as organic light-emitting diodes (OLEDs) and solar cells, or sensitizers used in photodynamic therapy. In such devices, triplet excitations are ubiquitously present but their annihilations can be either detrimental, e.g., giving rise to a roll-off of intensity in an OLED, or mandatory, e.g., if the sensitizer relies on up-conversion of long-lived low-energy triplet excitations. Since the employed materials are usually noncrystalline, optical excitations migrate via incoherent hopping. Here, we employ kinetic Monte Carlo simulations (KMC) to study the complex interplay of triplet-triplet annihilation (TTA) and quenching of the triplet excitations by impurities in a single-component system featuring a Gaussian energy landscape and variable system parameters such as the length of the hopping sites, i.e., a conjugated oligomer, the morphology of the system, the degree of disorder (\ensuremath{\sigma}), the concentration of triplet excitations, and temperature. We also explore the effect of polaronic contributions to the hopping rates. A key conclusion is that the DF features a maximum at a temperature that scales with $\ensuremath{\sigma}/{k}_{B}T$. This is related to disorder-induced filamentary currents and thus locally enhanced triplet densities. We predict that a maximum for the TTA process near room temperature or above requires typically a disorder parameter of at least 70 meV.

Rate Theory Model of Irradiation-Induced Solute Clustering in b.c.c. Fe-Based Alloys

Solute nanoclusters are critical to the structural and mechanical integrity of numerous alloys based on the b.c.c. Fe matrix, which have risen to prominence as candidates for advanced nuclear reactor applications. Because irradiation can profoundly alter the morphology and composition of these solute nanoclusters, it is critical to understand and predict solute clustering behavior in the presence of irradiation. In this study, we advance a simple theory to model irradiation-induced nanocluster evolution subject to different irradiating particles. The model is trained and validated with experimental data following an approach similar to training a machine learning algorithm, resulting in an agile model that can be used for rapid screening of new alloys. Using the model, nanocluster evolution is found to depend upon the disordering parameter (i.e., cluster morphology and dose rate) and irradiation temperature, and is most sensitive to the solute migration, vacancy formation, and vacancy migration energies. Results are discussed with respect to the irradiation temperature shift for varying irradiating particle types and dose rates.

Melting, freezing, and dynamics of two-dimensional dipole systems in screening bulk media.

This paper reports on the molecular dynamics simulations of classical two-dimensional (2D) electric dipole systems. The properties of 2D systems with bare (nonscreened) and screened dipole-dipole interactions have been investigated. Based on the polygon construction method, we present simulation results on the phase transition, and we locate the melting and freezing points of 2D dipole systems in terms of a polygon disorder parameter, with the polygon disorder parameter being the sum of nontriangular polygon order parameters. It was found that the phase transition of the system occurs when the polygon disorder parameter has a value 0.165. This result was cross-checked by using both local and overall orientational order parameters. We also identified that the value of the average local orientational order parameter at the phase transition point is 0.67. These results are valid for the ordinary (bare) dipole-dipole interaction as well as the screened dipole-dipole interaction, and they are expected to be general for other 2D systems with repulsive pair interaction. We observed that both melting and freezing points shift to lower values of temperature due to screening. In the liquid state, the radial distribution function and polygon construction method show the loss of order in a structure as screening becomes more severe. Furthermore, the impact of screening on the system's collective excitation spectra and diffusive characteristics at liquid and solid states has been studied. Results show the decrease in the values of both longitudinal and transverse sound speeds and the emergence of anomalous superdiffusive motion in the liquid state due to screening.

Relationship between anemia and biochemical parameters of mineral bone disorders in chronic kidney disease stages 3-5 pre-dialysis patients

Background: Anemia and mineral bone disorders (MBD) accompany chronic kidney disease (CKD) and worsen as CKD progresses. Different biochemical parameters of CKD-MBD have been associated with anemia of CKD but are less well evaluated in low resource settings. In this study, we evaluated the role CKD-MBD disorders as a cause of anemia in CKD non-dialysis patients.
 Methods: This cross-sectional study recruited 115 patients with CKD who attended outpatient department (OPD) of Nephrology in BIRDEM General Hospital between January and June 2019. Patients, who were on iron, erythropoietin, calcium or vitamin D therapy in any form within the preceding 3 months and patients with known parathyroid disorders, metabolic bone diseases or anemia with definite etiology were excluded. Each patient’s demographic, clinical and biochemical parameters were recorded. Associations between anemia and serum levels of calcium (corrected), phosphate, parathyroid hormone (PTH), 25-hydroxy vitamin D [25(OH)D] and alkaline phosphatase were evaluated.
 Results: Total patients were 115 including 71 (61.7%) females. Mean age was 57.8 years. Most patients were in CKD stage 4 (43, 37.4%) and 5 (45, 39.1%). Mean duration of diabetes and hypertension were 12.7 and 7.2 years respectively. Mean serum creatinine (mg/dL), hemoglobin (gm/dL), calcium (mg/dL), albumin (gm/L), phosphate (mg/dL), alkaline phosphatase (U/L), PTH (pg/mL) and 25(OH)D (ng/mL) were 3.1, 10.5, 8.7, 37.9, 4.0, 119.1, 211.1 and 15.1 respectively. Hemoglobin in CKD stages 3-5 pre-dialysis patients had positive correlation with calcium and 25(OH)D and negative correlation with phosphate, alkaline phosphatase and PTH. Among these parameters of CKD-MBD, correlation with alkaline phosphatase was significant (r=-0.352, p=0.001)
 Conclusion: Anemia in CKD patients is multifactorial and this study concludes that CKD-MBD is yet another entity contributing to anemia in such pre-dialysis patients.
 Birdem Med J 2020; 10(3): 187-191

Serum phosphate levels modify the impact of parathyroid hormone levels on renal outcomes in kidney transplant recipients

Separate assessment of mineral bone disorder (MBD) parameters including calcium, phosphate, parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D (1,25D) predict renal outcomes in kidney transplant recipients (KTRs), with conflicting results. To date, data simultaneously evaluating these parameters and interwoven relations on renal outcomes are scarce. We conducted a prospective long-term follow-up cohort study included 263 KTRs with grafts functioning at least 1 year after transplantation. The outcome was a composite of estimated GFR halving and graft loss. Cox regression analyses were employed to evaluate associations between a panel of six MBD parameters and renal outcomes. The outcome occurred in 98 KTRs during a median follow-up of 10.7 years. In a multivariate Cox analysis, intact PTH (iPTH), phosphate, and 1,25D levels were associated with the outcome (hazard ratio, 1.60 per log scale; 95% confidence interval, 1.19–2.14, 1.60 per mg/dL; 1.14–2.23 and 0.82 per 10 pg/mL; 0.68–0.99, respectively). Competing risk analysis with death as a competing event yielded a similar result. After stratification into four groups by iPTH and phosphate medians, high risks associated with high iPTH was not observed in KTRs with low phosphate levels (P-interaction < 0.1). Only KTRs not receiving active vitamin D, poor 1,25D status predicted the worse outcome (P-interaction < 0.1). High iPTH, phosphate, and low 1,25D, but not FGF23, levels predicted poor renal outcomes. Simultaneous evaluation of PTH and phosphate levels may provide additional information regarding renal allograft prognosis.

Tailored β-diketones as effective surface passivation for solution processed zinc oxide thin film transistors

Diketone passivation of defect states at the surface of solution-processed zinc oxide thin film transistors is investigated. Trifluoroacetylacetophenone is used as the basis for passivating molecules due to its easy chemical variability on the phenyl ring. Electron withdrawing or donating substituents can be introduced at the phenyl ring to vary the electron density at the ketone anchoring positions of the passivating molecule. The relative change of electron density is quantified by DFT calculations for different substituents. Experimentally thin zinc oxide films are prepared by aqueous spray pyrolysis, while passivating diketones are deposited in vacuum on the ZnO surface. XPS and AFM measurements confirm the successful deposition of passivating molecules at the zinc oxide surface. Electrical characterization of passivated zinc oxide transistors is carried out for different exposure times. All diketones improve transistor stability for positive and negative bias stress. The passivated transistors show improved electrical properties with increased electron mobility and decreased disorder parameter. Finally, threshold voltages shift systematically to negative values and hysteresis clearly reduces. The experimentally determined electrical properties of passivated zinc oxide transistors show a systematic correlation to the effective electron density at the oxygen anchor atoms of diketones and higher charge results in a better performance. • 1,3-diketone molecules as passivation with adjustable effective charge at oxygen. • Chemical passivation of zinc oxide surface defects. • High electron density at oxygen anchor atoms improves transistor performance best.

First-Principles Quantum and Quantum-Classical Simulations of Exciton Diffusion in Semiconducting Polymer Chains at Finite Temperature.

We report on first-principles quantum-dynamical and quantum-classical simulations of photoinduced exciton dynamics in oligothiophene chain segments, representative of intrachain exciton migration in the poly(3-hexylthiophene) (P3HT) polymer. Following up on our recent study (Binder R.; Burghardt, I. Faraday Discuss. 2020, 221, 406), multilayer multiconfiguration time-dependent Hartree calculations for a short oligothiophene segment comprising 20 monomer units (OT-20) are carried out to obtain full quantum-dynamical simulations at finite temperature. These are employed to benchmark mean-field Ehrenfest calculations, which are shown to give qualitatively correct results for the present system. Periodic boundary conditions turn out to significantly improve earlier estimates of diffusion coefficients. Using the Ehrenfest approach, a series of calculations are subsequently carried out for larger lattices (OT-40 to OT-80), leading to estimates for temperature-dependent mean-squared displacements, which are found to exhibit a near-linear dependence as a function of time. The resulting diffusion coefficient estimates are an increasing function of temperature, whose detailed functional form depends on the degree of static disorder. With a realistic static disorder parameter (σs ≃ 0.06 eV), the diffusion coefficients decrease from D ∼ 1 × 10-2 cm2 s-1 to D ∼ 1 × 10-3 cm2 s-1, in qualitative agreement with experimental data for P3HT. The dynamical scenario obtained from our simulations shows that exciton migration in P3HT-type chains is a largely adiabatic process throughout the temperature regime we investigated (i.e., T = 50-300 K). The resulting picture of exciton migration is a coherent, but not bandlike, motion of an exciton-polaron driven by fluctuations induced by low-frequency modes. This process acquires partial hopping character if static disorder becomes prominent and Anderson localization sets in.