High Charge Carrier Mobility Research Articles

Influence of Sn2+ doping to improve the charge transport and light-emitting properties of CsPbCl3 perovskites.

Doping B-site with metal ions is an emerging strategy to reduce lead toxicity and enhance the optoelectronic performance of lead halide perovskites. Also, the concentration of metal dopants plays an important role in achieving the desired electrical and optical properties of these halide perovskites. This work presents a simple chemical approach to synthesize pure and Sn2+ doped CsPbCl3 perovskites at room temperature. The dopant concentration was varied from 1 to 9 mol%. The structural, morphological, optical, thermal, and electrical properties of prepared perovskites are studied in order to check the optimal doping concentration along with to know the improvement in the optoelectronic properties required for LEDs and photovoltaic cells. It was observed that CsPbCl3 perovskites exhibit high photoluminescence intensity, blue/Violet emission, and high charge carrier mobility (up to 56.3 cm2/V-s) with a reduction in bandgap (up to 2.865 eV) after Sn2+ doping.

Benchmarking the integration of hexagonal boron nitride crystals and thin films into graphene-based van der Waals heterostructures

Abstract We present a benchmarking protocol that combines the characterization of boron nitride (BN) crystals and films with the evaluation of the electronic properties of graphene on these substrates. Our study includes hBN crystals grown under different conditions (atmospheric pressure high temperature, high pressure high temperature, pressure controlled furnace) and scalable BN films deposited by either chemical or physical vapor deposition (CVD or PVD). We explore the complete process from boron nitride growth, over its optical characterization by time-resolved cathodoluminescence (TRCL), to the optical and electronic characterization of graphene by Raman spectroscopy after encapsulation and Hall bar processing. Within our benchmarking protocol we achieve a homogeneous electronic performance within each Hall bar device through a fast and reproducible processing routine. We find that a free exciton lifetime of 1 ns measured on as-grown hBN crystals by TRCL is sufficient to achieve high graphene room temperature charge carrier mobilities of 80,000 cm2/(Vs) at a carrier density of |n| = 1×1012 cm−2, while respective exciton lifetimes around 100 ps yield mobilities up to 30,000 cm2/(Vs). For scalable PVD-grown BN films, we measure carrier mobilities exceeding 10,000 cm2/(Vs) which correlates with a graphene Raman 2D peak linewidth of 22 cm−1. Our work highlights the importance of the Raman 2D linewidth of graphene as a critical metric that effectively assesses the interface quality (i.e. surface roughness) to the BN substrate, which directly affects the charge carrier mobility of graphene. Graphene 2D linewidth analysis is suitable for all BN substrates and is particularly advantageous when TRCL or BN Raman spectroscopy cannot be applied to specific BN materials such as amorphous or thin films. This underlines the superior role of spatially-resolved spectroscopy in the evaluation of BN crystals and films for the use of high-mobility graphene devices.

Graphene Oxide-Doped Indium Oxide Buffer Film Sandwiched between Titanium Oxide Layers for the Development of Photosensitive Resistive Memory Devices.

Over the past decade, metal oxide semiconductors have attracted considerable attention because of their transparency, high intrinsic charge carrier mobility, and charge carrier density. Metal oxide semiconductors also provide a promising route to develop resistive memory devices because of the tunability of their conductivity via the removal of oxygen ions, forming oxygen vacancies that can act as electron donors. Here, this paper reports the fabrication of a resistive random-access memory (ReRAM) device with TiO2 and TiO2-x layers and introduces a solution-processed In2O3-graphene oxide (GO) buffer layer from a water-based precursor solution to tune the switching characteristics. The devices were compared with a ReRAM device with no buffer layer, and the device composition was optimized by tuning the GO concentration in the layers. The devices showed hysteresis under cyclically scanned bias between positive and negative voltages with clear switching between the low resistance state (LRS) and the high resistance state (HRS). The optimized device also showed a more than 3 orders of magnitude difference in resistance between the LRS and HRS and a stable current retention. The devices also showed photoresponsive behaviors. In the LRS, the current increased significantly under illumination, while in the HRS, the current deteriorated slowly when constantly illuminated. These results highlight the dual role of the GO flakes in the buffer layer by increasing the resistance in the HRS and providing a photoresponsive switching capability. The ReRAM device was connected to a TFT device, and its feasibility as a memory component in a digital circuit was successfully demonstrated. These results provide a new avenue for developing metal-oxide-based ReRAM devices with GO-containing active layers.

High Charge Carrier Mobility in Porphyrin Nanoribbons

Polydisperse edge‐fused nickel(II) porphyrin nanoribbons have been synthesized by Yamamoto coupling followed by gold(III)‐mediated fusion, with average degrees of polymerization of up to 37 repeat units (length 31 nm). Time‐resolved optical‐pump terahertz spectroscopy measurements indicate that photo‐generated charge carriers have dc mobilities of up to 205 cm2 V–1 s–1 in these nanoribbons, exceeding the values previously reported for most other types of nanoribbon or π‐conjugated polymer.

High Charge Carrier Mobility in Porphyrin Nanoribbons.

Polydisperse edge-fused nickel(II) porphyrin nanoribbons have been synthesized by Yamamoto coupling followed by gold(III)-mediated fusion, with average degrees of polymerization of up to 37 repeat units (length 31 nm). Time-resolved optical-pump terahertz spectroscopy measurements indicate that photo-generated charge carriers have dc mobilities of up to 205 cm2 V-1 s-1 in these nanoribbons, exceeding the values previously reported for most other types of nanoribbon or π-conjugated polymer.

High-performance thermoelectric PEDOT:PSS fiber bundles via rational ionic liquid treatment

Rapid growth of wearable technology generates increasing demand for lightweight and elastic energy harvesting systems. Among them, conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) shows great potential for lightweight and flexible thermoelectric generators. However, the practical applications of PEDOT:PSS have been restricted by the low Seebeck coefficient and power factor. Here, PEDOT:PSS/1,3-dimethylimidazolium dicyanamide (MMIM:DCA) fiber bundles with enhanced thermoelectric performance have been fabricated by optimizing the content of ionic liquids (ILs), and the duration of dual post-treatment with H2SO4 and NaBH4. The as-prepared fiber bundles exhibit a high power factor of 91.8 μW/m K−2 at 298 K. Detailed characterizations confirm that the phase separation and structural rearrangement of the polymer chains triggered by ILs ensure high charge carrier mobility, resulting in increased electrical conductivity. Meanwhile, the strong binding of DCA− to the PEDOT structure, combined with the hydrophilicity and potent reducing effect of MMIM+, synergistically alters the oxidation state of PEDOT, leading to an enhanced Seebeck coefficient. Moreover, the assembled flexible fiber bundle thermoelectric devices exhibit superior performance and usability, which show an output power density of 36.76 μW cm−2 with a temperature gradient of 25 K. This work offers valuable insights into the development of high-performance organic thermoelectric materials via the modulation of polymer chains.

SbSeI for high-efficient photocatalytic degradation of multiple pollutants

Photocatalytic degradation is an effective technology for degrading water pollution that plays a significant role in environmental remediation. Ternary 2D ternary V-VI-VIIA semiconductors are ideal candidates for photocatalytic degradation of pollutants due to effective light absorption and high charge carrier mobility. In this work, high-quality SbSeI crystals were prepared using the chemical vapor transport (CVT) method and their photocatalytic degradation performance for multiple pollutants was studied. SbSeI exhibits excellent photocatalytic performance in the degradation of potassium dichromate (Cr (VI)), rhodamine B (RhB), tetracycline hydrochloride (TC-HCl) and methyl orange (MO). More than 98% of Cr (VI) and RhB can be removed after irradiation with an Xe lamp for 10 min and 40 min, respectively. The capture experiments and electron spin resonance results indicated that ·O2− plays a major role in reducing Cr (VI), while h+ plays a primary role in the degradation of MO, RhB and TC-HCl. Interestingly, the degradation rate of Cr (VI) is 1.3 times higher than that of a single pollutant system, and the degradation rate of RhB is 1.6 times higher, due to the enhanced separation and utilization of holes and electrons. The results demonstrate that SbSeI is a potential photocatalytic degradation material.

Modelling of Cut-off Frequency of Armchair Graphene Nanoribbon Tunnel Field Effect Transistor Using Transfer Matrix Method

Graphene is considered as a promising two-dimensional material for electronic device applications due to its high charge carrier mobility and it is extremely thin in size. As a material, graphene has great potential for the development of high-speed nano electric devices. Graphene can be used as a channel material in Tunnel Field Effect Transistor (TFET). In this study, the cut-off frequency of the armchair graphene nanoribbon tunnel field effect transistor (AGNR-TFET) device was modelled quantum mechanically. The solution of the Dirac-like Hamiltonian and Poisson equations self-consistently is used to determine the potential profile of device and the transmittance is calculated using the transfer matrix method (TMM). The Landauer formulation with the help of Gauss Legendre Quadrature Method (GLQM) is used to calculate the tunnelling current and the cut-off frequency of AGNR-TFET. The calculation results showed that the cut-off frequency increased as the drain voltage increased, while the increase in channel length and the N-index graphene made the cut-off frequency decreased. Moreover, the thicker the oxide layer could increase the cut-off frequency and the higher the temperature on the device would reduce the cut-off frequency.

Unusual Cross-Conjugation in Cyclic Dipeptide-Based Building Blocks for Donor-Acceptor Semiconducting Conjugated Polymers.

Cross conjugation, though prevalent in many organic compounds, is typically considered less effective for electron delocalization compared to linear conjugation. Consequently, it is rarely used as the backbone structure for semiconducting conjugated polymers. In this study, we designed and synthesized a novel building block, TIDP, which features a central cyclic dipeptide with cross conjugation characteristics. Strong intramolecular hydrogen bonding interactions confer TIDP with a highly rigid and coplanar conformation. Importantly, theoretical calculations reveal that π electrons are well delocalized across the entire structure, despite its low aromaticity. Conjugated polymers incorporating TIDP exhibit high charge carrier mobilities, demonstrating the effective π electrons delocalization of this innovative building block. Our findings show that with rational design, cross conjugation can achieve effective π electrons delocalization, providing a valuable approach for developing high-performance conjugated polymers for organic electronic materials.

Unusual Cross‐Conjugation in Cyclic Dipeptide‐Based Building Blocks for Donor–Acceptor Semiconducting Conjugated Polymers

AbstractCross conjugation, though prevalent in many organic compounds, is typically considered less effective for electron delocalization compared to linear conjugation. Consequently, it is rarely used as the backbone structure for semiconducting conjugated polymers. In this study, we designed and synthesized a novel building block, TIDP, which features a central cyclic dipeptide with cross conjugation characteristics. Strong intramolecular hydrogen bonding interactions confer TIDP with a highly rigid and coplanar conformation. Importantly, theoretical calculations reveal that π electrons are well delocalized across the entire structure, despite its low aromaticity. Conjugated polymers incorporating TIDP exhibit high charge carrier mobilities, demonstrating the effective π electrons delocalization of this innovative building block. Our findings show that with rational design, cross conjugation can achieve effective π electrons delocalization, providing a valuable approach for developing high‐performance conjugated polymers for organic electronic materials.

First-principles modeling of electron-phonon scattering rates in graphene

Graphene, which has a high mobility of charge carriers, which exceeds the mobility of charge carriers for all known materials, is currently considered as one of the most promising materials for the creation of new semiconductor devices. The results of modeling of electron scattering rates are presented for the acoustic and optical phonons in a single layer of graphene without a substrate for small values of energy, which do not exceed 1 eV. When modeling these rates, variants of both emission and absorption of phonons are considered. The obtained dependences of the charge carrier scattering rates will allow us to study the main characteristics of charge carrier transport in semiconductor structures containing graphene layers by modeling using the Monte Carlo method. Characteristics and parameters of graphene can be used to create new heterostructure devices with improved output characteristics.

Experimental Detection of Topological Electronic State and Large Linear Magnetoresistance in SrSn4 Superconductor

AbstractWhile recent experiments confirm the existence of hundreds of topological electronic materials, only a few exhibit the coexistence of superconductivity (SC) and a topological electronic state. These compounds attract significant attention in forefront research because of the potential for the existence of topological SC, paving the way for future technological advancements. SrSn4 is known for exhibiting unusual SC below the transition temperature (TC) of 4.8 K. Recent theory predicts a topological electronic state in this compound, which is yet to be confirmed by experiments. Systematic and detailed studies of the magnetotransport properties of SrSn4 and its Fermi surface characterizations are also absent. For the first time, a quantum oscillation study reveals a nontrivial 𝝅‐Berry phase, very light effective mass, and high quantum mobility of charge carriers in SrSn4. Magnetotransport experiment unveils large linear transverse magnetoresistance (TMR) of more than 1200% at 5 K and 14 T. Angle‐dependent transport experiments detect anisotropic and fourfold symmetric TMR, with the maximum value (≈2000%) occurring when the angle between the magnetic field and the crystallographic b‐axis is 45°. The results suggest that SrSn4 is the first topological material with SC above the boiling point of helium that displays such high magnetoresistance.

Designing Contact Independent High-Performance Low-Cost Flexible Electronics.

Organic semiconductors enable low-cost solution processing of optoelectronic devices on flexible substrates. Their use in contemporary applications, however, is sparse due to persistent challenges in achieving the requisite performance levels in a reliable and reproducible manner. A critical bottleneck is the inefficiency associated with charge injection. Here, large-scale simulations are employed to identify operational windows where key device parameters that are difficult to control experimentally, such as the contact resistance, become less consequential to overall device functionality. This design methodology overcomes injection barrier limitations in organic field-effect transistors (OFETs), leading to high charge carrier mobility and significantly expanding the range of suitable electrode materials. Leveraging this new understanding, all-organic, solution-deposited OFETs are successfully fabricated on flexible substrates. These devices incorporate printed contacts and showcase mobilities exceeding 5cm2Vs-1. These results provide a route for accessing the fundamental limits of material properties even in the absence of ideal contacts - a critical step in establishing reliable structure/property relationships and optimal material design paradigms. While reducing the injection barrier and contact resistance remains critical for achieving high OFET performance, this work demonstrates a path toward consistently achieving high charge carrier mobility through device geometry design, ultimately reducing processing complexity and cost.

A comprehensive review on the usability of black phosphorus in energy and wastewater treatment

Increasing population and industrial development brings with it many problems that need to be solved, such as energy production, storage, saving, protection of limited reserves, and environmental pollution. Nanomaterials, which emerged with the introduction of nanotechnology into our lives, play an important role in many areas. The novel two-dimensional nanomaterial black phosphorus (BP) exhibits great potential in photocatalytic applications, energy technologies, and purification with properties such as broad light absorption spectrum, tunable direct band gap, and exceptionally high charge carrier mobility. This review gives a outline of the manufacturing techniques, structural, chemical, electrical and thermal properties of BP. Then, the success of BP derivatives with different dimensions and morphologies in environmental and energy applications is presented by comparing them with previous studies in these fields. The results show that heterojunction structures produced by combining BP with MoS2 and MOFs improve the electrochemical properties of BP, while carbonization processes increase its efficiency in battery and supercapacitor applications. Finally, in this review, a summary of BP’s potential future uses, awareness of easy production methods, and its activities in environmental and energy applications are discussed in a broad context.

Optoelectronics of Lead‐Free Antimony‐ and Bismuth‐Based Metal Halides for Sensitive and Low‐Noise Photodetection

AbstractOrganic–inorganic hybrid halide perovskites have emerged as the most promising optoelectronic materials for next‐generation solution‐processed devices, primarily attributed to their distinctive properties such as cost‐effectiveness, facile fabrication process, high light absorption coefficient, tunable bandgap, and relatively high charge carrier mobility. Nevertheless, the presence of Pb elements is inevitable in most high‐performance perovskite optoelectronic devices, posing environmental pollution concerns and impeding their commercialization. In this study, two novel non‐toxic bismuth‐ and antimony‐based perovskite materials with environmentally conscious approaches are developed. Their structures and optoelectronic properties have been systematically characterized. Subsequently, photoconductive‐ and photodiode‐type photodetectors are designed and fabricated. Notably, the photodiode configuration exhibits exceptionally low dark current and noise, superior detection sensitivity, fast response speed, and good device stability. Owing to these superior performance metrics, the devices demonstrate great potential for real applications. Furthermore, this study furnishes a theoretical framework and design perspectives for the solution‐processed semiconductor materials.

Enhancement of organic field-effect transistor performance via precision molecular alignment of a P4T2F-HD-based conjugated polymer

This study conducts a detailed exploration of how the orientation of molecules affects the efficiency of organic field-effect transistors (OFETs), with a particular focus on a new conjugated polymer, P4T2F-HD. The study examines the fabrication of both large-scale, anisotropically oriented thin films and non-oriented, isotropic thin films of P4T2F-HD through two separate approaches: the Unidirectional Film Transfer Method (UFTM) for oriented films and spin-coating for isotropic films. Results indicate that UFTM notably excels in directing the molecular alignment of P4T2F-HD across extensive areas, thereby creating anisotropic thin films, whereas spin-coating yields isotropic thin films lacking specific orientation. Further investigation into the properties of these films through various analytical techniques sheds light on the role of molecular orientation in influencing their electronic characteristics. OFETs fabricated with anisotropically oriented P4T2F-HD films exhibit markedly improved performance, characterized by higher charge carrier mobility and enhanced electrical stability, in comparison to their isotropic counterparts. The study evidences that the directional arrangement of macromolecules plays a pivotal role in OFETs functionality, with UFTM-derived films demonstrating a significant leap in field-effect mobility—showing an over 100-fold improvement over spin-coated films. This boost is linked to the effective charge transmission along the polymer chains, enabled by precise molecular alignment.

Single-Component Organic Solar Cells with over 14% Efficiency.

Single-component organic solar cells (SCOSCs), with covalently linked donor and acceptor, attract considerable attention for their improved thermodynamic stability over traditional bulk heterojunction (BHJ) organic solar cells. Despite the significant potential of SCOSCs, their efficiency has consistently trailed behind that of their BHJ counterparts for years, primarily due to challenges including rapid charge recombination, intricate phase separation, and substantial energy loss. Herein, this work represents a significant milestone in the advancement of SCOSCs based on a single component of PBDB-T-b-PYT, achieving both high efficiency (14.64%) and low energy loss (0.563 eV) through the combined use of thermal and solvent annealing. Optimized devices exhibit not only higher charge carrier mobilities but also a more balanced distribution, facilitating efficient transport and collection of photogenerated charge carriers by individual electrodes, while also demonstrating lower nonradiative recombination losses, thus contributing to superior optoelectronic performance and stability.

Plasmonic perovskite photodetector with high photocurrent and low dark current mediated by Au NR/PEIE hybrid layer

Hybrid organic-inorganic perovskite photodetectors have gained significant attention due to their superior potential for optoelectronic applications, offering various advantages such as low-cost processing, high charge carrier mobility, and lightweight properties. However, these perovskite photodetectors exhibit relatively low absorption in the near-infrared (NIR) range, which limits their potential applications. Here, to address this challenge, the integration of gold nanorods (Au NRs) utilizing localized surface plasmon resonance (LSPR) effects in the NIR range has been developed, leading to enhanced light absorption in the active region and higher photocurrent generation. Additionally, ∼7.9 nm of thin polyethyleneimine ethoxylated (PEIE) interlayers were incorporated into the Au NR photodetectors, suppressing dark current by blocking charge injection. As a result, the synergistic effect of the Au NR/PEIE hybrid layer has led to a high-performance photodetector with a responsivity of 0.360 A/W and a detectivity of 1.81 × 1010 Jones, demonstrating a noticeable enhancement compared to the control device. Finite-difference time-domain (FDTD) simulations, morphological characterizations, and photoluminescence studies further support the mechanism for enhancing the performance of the device. We believe that our plasmon-enhanced protocol holds strong potential as a promising platform for perovskite optoelectronic devices.

Role of Nanoparticle Size in the Photocatalytic Degradation of Pollutants

Purpose: The aim of the study was to assess the role of nanoparticle size in the photocatalytic degradation of pollutants. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The study indicated that smaller nanoparticles exhibit a higher surface area-to-volume ratio, providing more active sites for pollutant interaction and adsorption, which enhances the overall degradation process. Additionally, smaller nanoparticles tend to have higher charge carrier mobility and reduced recombination rates of electron-hole pairs, further improving photocatalytic activity. This increased efficiency is critical in environmental applications, as it allows for the effective breakdown of various contaminants, including dyes, pesticides, and pharmaceuticals, at lower catalyst loadings and shorter reaction times. The optimization of nanoparticle size, therefore, plays a crucial role in developing advanced photocatalytic systems for environmental remediation. Implications to Theory, Practice and Policy: Optical absorption theory, surface area and reaction kinetics theory and charge carrier dynamics theory may be used to anchor future studies on assessing the role of nanoparticle size in the photocatalytic degradation of pollutants. Develop robust methodologies for synthesizing nanoparticles with precise control over size distribution. Establish standardized protocols for evaluating the performance and safety of nanoparticle-based photocatalytic materials. This includes setting benchmarks for degradation efficiency, durability, and potential environmental impacts.

The features of magnetotransport properties of the Mn δ-doped GaAs structure with multiple conduction channels

The work examines the features of the magnetotransport and magnetooptical properties of a GaAs structure with a Mn δ-layer located near an In0.25Ga0.75As/GaAs quantum well with high charge carrier mobility. It is shown that in the initial structure, conduction occurs predominantly in the quantum well region, that leads to the dominance of magnetotransport phenomena of a Lorentzian nature (ordinary Hall effect and positive magnetoresistance). After suppression of the conduction channel through the quantum well using ion irradiation, an anomalous Hall effect and negative resistance are observed. It has been established that the experimental magnetic field dependences of the Hall resistance in ferromagnetic nanostructures with multiple conduction channels may not reflect the real magnetic properties of the structures.