Effective Mobility Research Articles

Atom-Scaled Hafnium Doping for Strengthening the Germanium Oxide Interfacial Layer of The Gate Stack of Germanium P-Type Metal-Oxide-Semiconductor Field Effect Transistor

We have developed a method that uses a half-cycle Hf precursor adsorption to subtly dope GeO2 IL of the Hf-based gate stack through in situ plasma-enhanced atomic layer deposition. This technique can effectively reduce GeO vaporization and improve the thermal stability of the GeO2 layer. Our results indicated that the accumulation capacitance (Cacc) undergoing higher temperatures showed no noticeable increase in the capacitance-voltage (CV) curves once Hf was delicately introduced into the GeO2 layer. According to the Ge 3d spectra of X-ray photoelectron spectroscopy, we found that the IL had a signal from extra Hf-O bonds; thus, we conclude GeO evaporation can be suppressed substantially by Hf incorporation. As a result, adding metal into GeOx IL to form HfGeOx achieved a remarkably low leakage current of 9 × 10−5 A cm−2 and the lowest interface trap density (Dit) of approximately 2 × 1011 eV−1 cm−2 at 500 °C of PMA. In addition, applying this gate stack structure to device fabrication significantly reduced the leakage current of the off-state and improved the effective peak hole mobility.

Computational method on highly efficient D-π-A-π-D-based different molecular acceptors for organic solar cells applications and non-linear optical behaviour

Eight molecular structures (BT-A1 to BT-A8) with high-performance non-fullerene acceptor (NFA) were selected for organic solar cells (OSCs) and non-linear optical (NLO) applications. Their electronic, photovoltaic (PV) and optoelectronic properties were tuned by adding powerful electron-withdrawing groups to the acceptor (A) of the D-π-A-π-D structure. Using time-dependent density functional theory (TD-DFT) techniques, based on the laws of quantum chemical calculations, the absorption spectra, stability of the highest and lowest-energy molecular orbitals (HOMO/LUMOs), electron density, intramolecular charge transfer (ICT), transition density matrix (TDM), were examined. The binding energy (Eb) and density of states (DOS) were probed to realize the optoelectronic analysis of the structures BT-A1 to BT-A8. Noncovalent interactions (NCIs) based on a reduced density gradient (RDG) were used to describe the nature and strength of D-A interactions in the molecules BT-A1 to BT-A8. The new refined molecules BT-A1 to BT-A8 exhibited strong absorbance bands between 408–721 nm and high electron transfer contribution (ETC) ranges between 87–96 %, along with the smallest excitation energies (Ex) between 1.71–3.55 eV in the solvent dichloromethane. Dipolar moment strengths ranging from 0.38 to 4.72 Debye in both the excited and ground states have determined with good solubility properties of BT-A1 to BT-A8 in polar solvent. Highly effective charge mobilities and prevention of charge recombination have been demonstrated by the electron (0.18–0.41 eV) and hole RE values (0.13–0.89 eV) for the new compounds. Power conversion efficiencies (PCE) of BT-A1 to BT-A8 were nearly the same because of better outcomes compared to the molecules in the BT. Compared to poly[4.8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b: 4,5-b']dithiophene-2,6- diyl-alt-(4–2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2–6-diyl)] (PTB7-Th), the open circuit voltages (Voc) of compounds BT-A1 to BT-A8 were ranged from 1.52 to 2.13 eV. The polarizability (α) and hyperpolarizability (β) of the molecules BT-A1 to BT-A8 were used to determine the non-linear optical (NLO) properties. The results showed that BT-A2, BT-A6 and BT-A7 have good NLO activity. This computational analysis demonstrates the superiority of the molecules with NFA. Hence the compounds are advised for the use in production of high-performance OSCs and NLO activity.

Capillary Electrophoresis as a Complementary Analytical Tool for the Separation and Detection of Nanoplastic Particles.

Capillary electrophoresis (CE) is presented as a technique for the separation of polystyrene nanoparticles (NPs, particle diameters ranging from 30 to 300 nm) through a bare fused silica capillary and ultraviolet detection. The proposed strategy was also assessed for other types of nanoplastics, finding that stronger alkaline conditions, with an ammonium hydroxide buffer (7.5%, pH = 11.9), enabled the separation of poly(methyl methacrylate), polypropylene, and polyethylene NP for the first time by means of CE for particle diameters below 200 nm. Particle behavior has been investigated in terms of its effective electrophoretic mobility, showing an increasing absolute value of effective electrophoretic mobility from the smaller to the larger sizes. On the other hand, the absolute value of surface charge density decreased with increasing size of NPs. It was demonstrated and quantified that the separation mechanism was a combination of linear and nonlinear electrophoretic effects. This work is the first report on the quantification of nonlinear electrophoretic effects on nanoplastic particles in a CE system.

A Comparison of Hilbert and Fast Fourier Transform Techniques for Reciprocating Motors

Human existence has been significantly impacted by the growth of information and technology, particularly in relation to the requirement for effective mobility. But as a car ages, symptoms that affect its performance and safety start to show. These symptoms are a serious worry. Interference with car parts, such coils, is one issue that can have a major effect on driving safety and performance. Vibration analysis techniques have been successful in addressing this problem by detecting damage to different car parts. With the intention of comprehending piston motor vibration characteristics at different rotational speeds. The piston motor was used to collect vibration data at three distinct speeds: 900 rpm, 1500 rpm, and 3500 rpm. Both the Hilbert approach, which offers profound insight into frequency energy, and an FFT analyzer, which produces clear frequency spectrum information, were used in the analysis. The findings demonstrated that vibration characteristics changed in response to variations in reciprocating motor speed. On the other hand, the average frequency energy tends to remain constant across a range of speeds, suggesting that the features of reciprocating motors may be complicated and not very affected by variations in speed. According to this study, different perspectives on the vibration characteristics of piston motors operating at different speeds can be gained by utilizing vibration analysis techniques like FFT and Hilbert. Improved comprehension of this phenomenon could have a significant impact on maintenance initiatives and performance analysis of vehicles. To fully understand the complexity of vibration characteristics in reciprocating motors at various speed conditions, more research will be needed

Direct quantification of ion composition and mobility in organic mixed ionic-electronic conductors.

Ion transport in organic mixed ionic-electronic conductors (OMIECs) is crucial due to its direct impact on device response time and operating mechanisms but is often assessed indirectly or necessitates extra assumptions. Operando x-ray fluorescence (XRF) is a powerful, direct probe for elemental characterization of bulk OMIECs and was used to directly quantify ion composition and mobility in a model OMIEC, poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS), during device operation. The first cycle revealed slow electrowetting and cation-proton exchange. Subsequent cycles showed rapid response with minor cation fluctuation (~5%). Comparison with optical-tracked electrochromic fronts revealed mesoscale structure-dependent proton transport. The calculated effective ion mobility demonstrated thickness-dependent behavior, emphasizing an interfacial ion transport pathway with a higher mobile ion density. The decoupling of interfacial effects on bulk ion mobility and the decoupling of cation and proton migration elucidate ion transport in conventional and emerging OMIEC-based devices and has broader implications for other ionic conductors writ large.

Towards complete development finance data: Quantifying China's international education co‐operation and presence in the Global South

AbstractMotivationChina does not participate in the development co‐operation reporting mechanism of the Organisation for Economic Co‐operation and Development's (OECD) development co‐operation reporting mechanism, nor does it voluntarily publish overseas development finance data. Despite recent quantitative research on China's foreign aid to other sectors, such as health, no precedent exists for quantifying China's international education co‐operation (IEC).PurposeThis article will use AidData's Chinese Official Finance Dataset (AidData 2.0) to estimate the IEC using the OECD's internationally standardized definitions of development finance and frameworks for classifying IEC projects.Approach and methodsWe thoroughly examined all types of IEC projects, including official finance projects other than those that meet the definition of official development assistance (ODA). In our comparative analysis of educational aid between China and traditional donors, we focused on ODA‐like projects and examined the number of projects and funding amounts to determine China's IEC priorities.FindingsThe result shows that, between 2000 and 2017, China's IEC commitments totalled 1,524 education‐related international projects, representing 12% of the total international finance project portfolio, most of which are in Africa. Compared to the OECD framework, China prioritized higher education (n = 784, 51%) and education facilities and training (n = 244, 16%). An estimate of cumulative funding between 2000 to 2017 showed that China was the 10th largest donor of education aid to African countries, behind France, the World Bank, Germany, the United States, the EU, the United Kingdom, Canada, Japan, and the Netherlands.Policy implicationsThe findings of this study help our understanding of China's IEC finance. With China's involvement in education development aid growing in recent years and donors looking for solutions to developing countries' debt crises, this will allow for more effective collaboration, co‐ordination, and resource mobilization for both donor and recipient countries.

Challenges and opportunities in achieving secure hospital clinical mobility management: An illustrative use case

Objective: To qualitatively describe a use case at Yale New Haven Health System (YNHHS) illustrating the need for and effective deployment of innovative technologies to manage an enterprise-owned shared device (EOSD) management program. EOSD management provides clinicians with secure, rapid access to enterprise mobile devices and applications, maintains devices in functional, use ready condition for clinicians, and enables enterprise tracking and reduced loss of devices.Methods: Executive leaders in clinical information technology and informatics management at YNHHS were interviewed through written and telephonic communication. Qualitative data was gathered through communications between clinical and information technology executives and the implementation support team of a leading identity and access management (IAM) solutions and EOSD management solution provider. Use case information was gathered, integrated and shared with health system executives and health IT/informatics leaders to verify the description of unmet needs, solution objectives and impact/value delivered after implementation of the EOSD management solution.Results: Benefits realized from implementation of an enterprise-shared mobility management solution included establishment of a cohesive and comprehensive enterprise-owned, shared device management strategy. This included effective monitoring and dynamic management of the system’s mobile device fleet, and better IT resource management with reduced mobile device loss. The IT administrative burden was reduced. While not surveyed systematically, improved clinician experience and satisfaction were reported to IT leaders anecdotally. EOSD management solution deployment was rapid, as was the time to improved clinician mobile experience and clear demonstration of value.Conclusions: A leading US health system was able to rapidly deploy a shared mobile device management solution that enabled effective monitoring and dynamic management of the enterprise mobile device fleet, with easier and faster clinician device access and workflows, and reduced IT administrative demand and costs. While the complexities associated with increased clinical mobility in healthcare will likely continue to grow, issuing future device and mobile management challenges that require effective hospital system response, technologies have emerged that enable more effective, efficient and satisfactory organizational mobility performance.

Investigation of Interlayer Dielectric in BaTiO3/III‐Nitride Transistors

In this study, the impact of varying the thickness of the Al2O3 interlayer dielectric on the electrical characteristics of BaTiO3/III‐nitride transistors is investigated. In the findings, it is revealed that a minimum thickness of 8 nm for the Al2O3 layer is crucial to maintain high device performance and protect against sputtering‐induced damage during BaTiO3 deposition. The fabricated BaTiO3/Al2O3/AlGaN/GaN high electron mobility transistors exhibit exceptional electrical properties, including a maximum current density of 700 mA mm−1, an on‐resistance of 5 Ω mm, an ION/IOFF ratio of 107, a subthreshold slope of 119 mV dec−1, and significantly reduced gate leakage current. The devices with the optimal 8 nm Al2O3 thickness demonstrates excellent agreement between theoretical and experimental values for effective mobility, achieving a value of 1188 cm2 V−1·s at a 2D electron gas density of 1013 cm−2. Furthermore, in the study, it is confirmed that increasing the Al2O3 thickness also improves the quality of interface charge density, as evidenced by the results obtained from capacitance–voltage measurements. In these findings, the critical role of controlling the Al2O3 thickness in optimizing the electrical characteristics and overall performance of BaTiO3/III‐nitride transistors are highlighted.

Chemotactic particles as strong electrolytes: Debye-Hückel approximation and effective mobility law.

We consider a binary mixture of chemically active particles that produce or consume solute molecules and that interact with each other through the long-range concentration fields they generate. We analytically calculate the effective phoretic mobility of these particles when the mixture is submitted to a constant, external concentration gradient, at leading order in the overall concentration. Relying on an analogy with the modeling of strong electrolytes, we show that the effective phoretic mobility decays with the square root of the concentration: our result is, therefore, a nonequilibrium counterpart to the celebrated Kohlrausch and Debye-Hückel-Onsager conductivity laws for electrolytes, which are extended here to particles with long-range nonreciprocal interactions. The effective mobility law we derive reveals the existence of a regime of maximal mobility and could find applications in the description of nanoscale transport phenomena in living cells.

Characteristics Analysis of IGZO TFT and Logic Unit in the Temperature Range of 8–475 K

The effect of high- and low-temperature conditions on the performance of IGZO TFT and logic circuits were investigated in this work. In the temperature range of 250−350 K, the performance of the IGZO TFT did not show significant changes and exhibited a certain degree of high- and low-temperature resistance. When the temperature was below 250 K, as the temperature decreased, the threshold voltage (VTH) of the IGZO TFT significantly increased, the field effect mobility (μFE) and the on state current (ION) significantly decreased. This is attributed to the lower excitation degree of charge carriers at extremely low temperatures, resulting in fewer charge carriers transitioning to the conduction or valence bands, and the formation of defects also limits carrier migration. When the temperature exceeded 350 K, as the temperature increased, more electrons could escape from the bandgap trap state and become free charge carriers, and the IGZO layer was thermally excited to produce more oxygen vacancies, resulting in higher μFE and lower VTH. In addition, the drain current noise spectral density of IGZO TFT conformed to the 1/ƒ noise characteristic, and the degradation mechanism of IGZO TFT over a wide temperature range was confirmed based on the changes in noise spectral density at different temperatures. In addition, an inverter logic unit circuit was designed based on IGZO TFT, and the performance changes over a wide temperature range were analyzed. This lays the foundation for IGZO TFT to be applied in integrated circuits with harsh environments.

Universal Design and Efficient Synthesis for High Ambipolar Mobility Emissive Conjugated Polymers.

High ambipolar mobility emissive conjugated polymers (HAME-CPs) are perfect candidates for organic optoelectronic devices, such as polymer light emitting transistors. However, due to intrinsic trade-off relationship between high ambipolar mobility and strong solid-state luminescence, the development of HAME-CPs suffers from high structural and synthetic complexity. Herein, a universal design principle and simple synthetic approach for HAME-CPs are developed. A series of simple non-fused polymers composed of charge transfer units, π bridges and emissive units are synthesized via a two-step microwave assisted C-H arylation and direct arylation polymerization protocol with high total yields up to 61 %. The synthetic protocol is verified valid among 7 monomers and 8 polymers. Most importantly, all 8 conjugated polymers have strong solid-state emission with high photoluminescence quantum yields up to 24 %. Furthermore, 4 polymers exhibit high ambipolar field effect mobility up to 10-2 cm2 V-1 s-1, and can be used in multifunctional optoelectronic devices. This work opens a new avenue for developing HAME-CPs by efficient synthesis and rational design.

Universal Design and Efficient Synthesis for High Ambipolar Mobility Emissive Conjugated Polymers

AbstractHigh ambipolar mobility emissive conjugated polymers (HAME‐CPs) are perfect candidates for organic optoelectronic devices, such as polymer light emitting transistors. However, due to intrinsic trade‐off relationship between high ambipolar mobility and strong solid‐state luminescence, the development of HAME‐CPs suffers from high structural and synthetic complexity. Herein, a universal design principle and simple synthetic approach for HAME‐CPs are developed. A series of simple non‐fused polymers composed of charge transfer units, π bridges and emissive units are synthesized via a two‐step microwave assisted C−H arylation and direct arylation polymerization protocol with high total yields up to 61 %. The synthetic protocol is verified valid among 7 monomers and 8 polymers. Most importantly, all 8 conjugated polymers have strong solid‐state emission with high photoluminescence quantum yields up to 24 %. Furthermore, 4 polymers exhibit high ambipolar field effect mobility up to 10−2 cm2 V−1 s−1, and can be used in multifunctional optoelectronic devices. This work opens a new avenue for developing HAME‐CPs by efficient synthesis and rational design.

Enhanced Electrical Transport Properties of Molybdenum Disulfide Field-Effect Transistors by Using Alkali Metal Fluorides as Dielectric Capping Layers.

The electronic properties of 2D materials are highly influenced by the molecular activity at their interfaces. A method was proposed to address this issue by employing passivation techniques using monolayer MoS2 field-effect transistors (FETs) while preserving high performance. Herein, we have used alkali metal fluorides as dielectric capping layers, including lithium fluoride (LiF), sodium fluoride (NaF), and potassium fluoride (KF) dielectric capping layers, to mitigate the environmental impact of oxygen and water exposure. Among them, the LiF dielectric capping layer significantly improved the transistor performance, specifically in terms of enhanced field effect mobility from 74 to 137 cm2/V·s, increased current density from 17 μA/μm to 32.13 μA/μm at a drain voltage of Vd of 1 V, and decreased subthreshold swing to 0.8 V/dec The results have been analytically verified by X-ray photoelectron spectroscopy (XPS) and Raman, and photoluminescence (PL) spectroscopy, and the demonstrated technique can be extended to other transition metal dichalcogenide (TMD)-based FETs, which can become a prospect for cutting-edge electronic applications. These findings highlight certain important trade-offs and provide insight into the significance of interface control and passivation material choice on the electrical stability, performance, and enhancement of the MoS2 FET.

Enhancing Stability and Performance in Tin-Based Perovskite Field-Effect Transistors Through Hydrogen Bond Suppression of Organic Cation Migration.

Ion migration poses a substantial challenge in perovskite transistors, exerting detrimental effects on hysteresis and operational stability. This study focuses on elucidating the influence of ion migration on the performance of tin-based perovskite field-effect transistors (FETs). It is revealed that the high background carrier density in FASnI3 FETs arises not only from the oxidation of Sn2+ but also from the migration of FA+ ions. The formation of hydrogen bonding between FA+ and F- ions efficiently inhibits ion migration, leading to a reduction in background carrier density and an improvement in the operational stability of the transistors. The strategy of hydrogen bond is extended to fluorine-substituted additives to improve device performance. The incorporation of 4-fluorophenethylammonium iodide additives into FETs significantly minimizes the shift of turn-on voltage during cyclic measurements. Notably, an effective mobility of up to 30 cm2 V-1 s-1 with an Ion/off ratio of 107 is achieved. These findings hold promising potential for advancing tin-based perovskite technology in the field of electronics.

A spectroscopic study of the stability of uranyl-carbonate complexes at 25–150 °C and re-visiting the data available for uranyl-chloride, uranyl-sulfate, and uranyl-hydroxide species

The stabilities of uranyl-carbonate and uranyl-hydroxide aqueous complexes were experimentally determined at temperatures ranging from 25 to 125 °C using in situ UV–vis and Raman spectroscopic techniques. Combined with earlier determinations of the stability of chloride, sulfate, and hydroxide complexes at temperatures up to 250 °C, these data permit to create a consolidated dataset suitable for modeling of U(VI) mobilization in natural systems. The parameters of the Modified Ryzhenko-Bryzgalin and the Helgeson-Kirkham-Flowers (HKF) Equations of State (EoS) were derived based on this dataset and used for thermodynamic modeling different scenarios of U(VI) mobilization. These models suggest that at conditions relevant to natural systems, carbonate-mediated transport of U(VI) is likely suppressed by the high stability of solid UO2(OH)2 and Na2U2O7. In contrast, sulfate-mediated mobilization mechanisms are highly efficient at acidic and near-neutral pH conditions and can lead to effective hydrothermal mobilization of U(VI).

Green perspective of N-CDs towards energy crisis and photodegradation of toxic dyes

Here we have presented a general overview of an environmental friendly, one-step, cost-effective, and efficient microwave irradiation method for the preparation of self heteroatom doped Nitrogen doped carbon dots (N-CDs) which demonstrated an average size of less than 10 nm and an interplaner distance of 0.334 nm. These N-CDs possess 2.35 eV energy gap with 65.5% fluorescence quantum yield. The surfaces of these graphitic-like structures are doped with (S, P, K, Mg, Zn) = 1% along with the extra passivating agent nitrogen (N). They have demonstrated wider absorption (between 300 and 550 nm) and emission (between 400 and 600 nm) bands and also managed enormous active surface sites and defects, that further extend its usage in energy harvesting, storage and photo catalysis owing to their unique property of electron transport and collection system. In addition, we have prepared, tested, and optimised new TiO2/N-CDs composite as photo anode and N-CDs/CB composite as photo cathode for application in dye-sensitized solar cells (DSSC). The achieved power conversion efficiency of the DSSC employed photoanode N-CDs/TiO2 and counter electrode carbon black/N-CDs, demonstrated a substantial improvement, in photo current and photo voltage owing to their multiple factor visible light absorption, effective electron separation, and longer recombination time resulted a Jsc. of 22.90 mA cm2, Voc. of 0.780 V, FF. of 74% and an overall PCE of about 13.22% approximating 2.5-fold increase in power conversion efficiency as compared to that of pure TiO2 and platinum based DSSC, where Jsc. (= 10 mA cm2), Voc. (= 0.750 V) and a total of 5.42% power efficiency. Furthermore, TiO2 was modified with Heteroatom-doped N-CDs using a novel ultrasonic immersion technique, and demonstrated greater photocatalytic activity for the degradation of methylene blue (85%) with a rate constant of 0.1068 in accordance with the pure TiO2 film and N-CDs which have showed only 20% and 30% photodegradation with lower rate constants under short UV irradiation, demonstrating the formation of reactive oxygen species and H+ ions in the sample solution resulting enhanced effective mobility of electrons and holes between TiO2/N-CDs composite nanomaterial, resulted greater photo degradation.

Factors Affecting the Financial Performance of Banks in the Era of Digital Transformation: A Perspective from Vietnam’s Banking Industry

This study aims to explore the factors influencing the financial performance of banks in Vietnam amidst the on-going digital transformation. In today's dynamic economic landscape, characterised by digital transformation and heightened regulatory standards, banks are compelled to innovate in response to continuous macroeconomic fluctuations. While the importance of increasing financial performance was largely recognised, the development and empirical validation of a financial performance model in the banking digital transformation context is not yet completely addressed, especially in developing countries. Utilising foundational theories, this research employed SMARTPLS 4 software alongside a blend of quantitative and qualitative analyses to assess the influences on the financial performance of banks amid digital transformation. Data were collected from 400 bank employees from all genders across Vietnam by the quota sampling method. Most of the survey participants lived in big cities where many banks were concentrated. The research results showed that there were three main factors directly affecting bank financial performance including Deposit mobilisation, Bank profitability, and Loyalty respectively according to the level of impact. This result highlights the importance of effective deposit mobilisation in achieving the bank's financial goals. The results also indicated that the growth of banks' profits is closely tied to their capacity to maintain loyal customers. Additionally, the study revealed a strong correlation between nine other factors, such as Savings Interest rates, Bank technology, and Inflation, with three intermediary factors. Until now, there are very few studies that have comprehensively evaluated both financial and non-financial factors' effect on bank financial performance as this research. This study also offered compelling insights into the strategies of successful banks in Vietnam today, underscoring the importance of investing in bank technology and presenting valuable recommendations. Based on the findings, banks can specifically focus on managing the identified variables and deploying appropriate business strategies to enhance their financial performance for sustainable development in the digital age.

Stem Cells Collection and Mobilization in Adult Autologous/Allogeneic Transplantation: Critical Points and Future Challenges.

Achieving successful hematopoietic stem cell transplantation (HSCT) relies on two fundamental pillars: effective mobilization and efficient collection through apheresis to attain the optimal graft dose. These cornerstones pave the way for enhanced patient outcomes. The primary challenges encountered by the clinical unit and collection facility within a transplant program encompass augmenting mobilization efficiency to optimize the harvest of target cell populations, implementing robust monitoring and predictive strategies for mobilization, streamlining the apheresis procedure to minimize collection duration while ensuring adequate yield, prioritizing patient comfort by reducing the overall collection time, guaranteeing the quality and purity of stem cell products to optimize graft function and transplant success, and facilitating seamless coordination between diverse entities involved in the HSCT process. In this review, we aim to address key questions and provide insights into the critical aspects of mobilizing and collecting hematopoietic stem cells for transplantation purposes.

Superior electron mobility, red electroluminescence with high quantum efficiency from printable room temperature columnar liquid crystalline perylene bisimide

Synthesis of highly fluorescent compounds is currently a critical requirement to facilitate the economical and metal-independent manufacture of organic light-emitting diodes (OLEDs) on a large scale. This study presents a highly soluble, swallow tail based electron deficient perylene bisimide (PBIST) exhibiting room temperature columnar oblique (Colob) liquid crystalline behavior along with a high photoluminescence quantum yield, positioning itself as a promising candidate for efficient OLEDs. Incorporation of swallow tails helped in enhancing the solubility and reduction of the clearing points. This unique tailor-made molecular design with the liquid crystalline phase allowed a demonstration of n-type field effect mobility of 0.008 cm2 V−1s−1 when annealed in the liquid crystalline mesophase range (at 70 °C) which can be exploited in the fabrication of printable electronic devices. Capitalizing on the high charge transport and luminescence attributes of PBIST, a series of devices were fabricated by utilizing PBIST as a single emitter and dispersed at different concentrations of 0.3, 0.5 and 1 wt% in host material CBP. Impressively, doped devices featuring the CBP as a host at a 0.5 wt% PBIST concentration exhibited an external quantum efficiency (EQE) as high as 7 %, accompanied by a luminance of 1787 cd/m2. The high EQE is attributed mainly to the triplet–triplet annihilation (TTA) process. This notable EQE enhancement signifies a substantial stride towards expanding the utility of multifunctional columnar self-assembled materials for the advancement of OLEDs.

Dynamical theory of topological defects II: universal aspects of defect motion

We study the dynamics of topological defects in continuum theories governed by a free energy minimization principle, building on our recently developed framework (Romano et al 2023 J. Stat. Mech. 083211). We show how the equation of motion of point defects, domain walls, disclination lines and any other singularity can be understood with one unifying mathematical framework. For disclination lines, this also allows us to study the interplay between the internal line tension and the interaction with other lines. This interplay is non-trivial, allowing defect loops to expand, instead of contracting, due to external interaction. We also use this framework to obtain an analytical description of two long-lasting problems in point defect motion, namely the scale dependence of the defect mobility and the role of elastic anisotropy in the motion of defects in liquid crystals. For the former, we show that the effective defect mobility is strongly problem-dependent, but it can be computed with high accuracy for a pair of annihilating defects. For the latter, we show that at the first order in perturbation theory, anisotropy causes a non-radial force, making the trajectory of annihilating defects deviate from a straight line. At higher orders, it also induces a correction in the mobility, which becomes non-isotropic for the +1/2 defect. We argue that, due to its generality, our method can help to shed light on the motion of singularities in many different systems, including driven and active non-equilibrium theories.