Polymer Blends and Composites

This article reviews the recent advances in organic electronics based on polymer blends with one-dimensional (1D) nanowires (NWs) of π-conjugated polymers. Self-assembled polymer semiconducting NWs are fascinating building blocks for their directional extension of inter- and intramolecular π-conjugation. This extensive conjugation provides unique electrical and optical properties that benefit applications in organic electronic devices. Outstanding performances are particularly expected from blending these NWs with insulating polymers or semiconducting molecules. Several representative reports describing NWs prepared from semiconducting/insulating polymer blends, conjugated block copolymers, or electrospinning for use as high-performance organic thin-film transistors (OTFTs) are discussed. The concepts of phase-separation behavior and the growth of crystalline NWs from multi-phase blend solutions are also illustrated. Research into the solubility-induced formation of NWs from semiconducting polymer/n-type small molecule blends for high-efficiency organic photovoltaic solar cells (OPVs) is introduced. In addition, the effects of the chemical properties of conjugated polymers on the optical and electrical properties of NWs and the use of ordered NW structures in OPVs are summarized. This critical review provides insights and a new perspective on the optimization of blend morphologies, which consequently enhances the performance of organic electronic devices.

Organic electronic devices have demonstrated tremendous versatility in a wide range of applications including consumer electronics, photovoltaics, and biotechnology. The traditional interface of organic electronics with biology, biotechnology, and medicine occurs in the general field of sensing biological phenomena. For example, the fabrication of hybrid electronic structures using both organic semiconductors and bioactive molecules has led to enhancements in sensitivity and specificity within biosensing platforms, which in turn has a potentially wide range of clinical applications. However, the interface of biomolecules and organic semiconductors has also recently explored the potential use of natural and synthetic biomaterials as structural components of electronic devices. The fabrication of electronically active systems using biomaterials-based components has the potential to realize a large set of unique devices including environmentally biodegradable systems and bioresorbable temporary medical devices. This article reviews recent advances in the implementation of biomaterials as structural components in organic electronic devices with a focus on potential applications in biotechnology and medicine.

Organic electronics has made great progress in the past decades, which is inseparable from the innovative development of organic electronic devices and the diversity of organic semiconductor materials. It is worth mentioning that both of these great advances are inextricably linked to the development of organic high-performance semiconductor materials, especially the representative n-type organic small-molecule semiconductor materials with high electron mobilities. The n-type organic small molecules have the advantages of simple synthesis process, strong intermolecular stacking, tunable molecular structure, and easy to functionalize structures. Furthermore, the n-type semiconductor is a remarkable and important component for constructing complementary logic circuits and p-n heterojunction structures. Therefore, n-type organic semiconductors play an extremely important role in the field of organic electronic materials and are the basis for the industrialization of organic electronic functional devices. This review focuses on the modification strategies of organic small molecules with high electron mobility at molecular level, and discusses in detail the applications of n-type small-molecule semiconductor materials with high mobility in organic field-effect transistors, organic light-emitting transistors, organic photodetectors, and gas sensors.

Organic spintronics can be divided into two major topics: magnetic field effect and spin injection. It has been shown that external magnetic field can significantly change photoluminescence, injection current, electroluminescence and photocurrent in organic semiconducting materials, which corresponds to magnetic field effect in organic semiconducting materials. In recent years, magnetic field effects in non-magnetic organic semiconducting materials have attracted intensive attention and research interest. They have emerged as powerful experimental tools to study useful and unuseful processes in charge-transport and excited states in organic electronic, optic and optoelectronic devices, providing effective approaches to tackle bottle-neck problems in charge-transport and excited states processes and offering scientific principles for muti-functional integration of magnetic, optical and electronic properties. In addition, magnetic field effects open new avenues to enhance energy conversion efficiency, frequency range and sensitivity in optoelectronic detecting or sensing devices. Furthermore, spin injection and its tuning on charge-transport and excited states processes based on ferromagnetic electrodes in organic semiconducting materials and devices can be used to develop novel functional spin-optoelectronic devices. This paper reviews the fundamental processes involved in the effects of magnetic field and spin injection on optoelectronic functions in organic semiconducting materials and devices.

A Busy March Meeting Is Brewing in Seattle

Conventionally, P–N junctions have played an important role as a key unit in most semiconductor electronic devices. P–N junctions based on organic semiconductors have also been researched widely, but it is difficult to develop solution‐processing‐based organic semiconductor P–N junctions because of their similar solubility in common organic solvents. For this reason, most organic planar heterojunctions have been based on deposition by thermal evaporation or transfer film via additional complicated processing. In this study, using p‐type and n‐type conjugated polymers with selection of their orthogonal solvents, a conjugated polymer bilayer P–N heterojunction structure is developed via simple solution processing. The developed structure is then used in novel organic electronic applications, such as organic rectifier diodes, organic field‐effect transistors with highly balanced ambipolar charge transport properties, integrated circuits, and even organic phototransistors that display a photoresponse from the visible to the near‐infrared (NIR) range with the generation of a photocurrent at the P–N heterointerface in the channel region. The polymeric P–N junction structure can be applied in various organic electronic devices via a simple printing process, which can contribute to the development of new functionalized organic electronics systems.

Background: Organic field effect transistors (OFETs), used in the fabrication of nanosensors, are one of the most promising devices in organic electronics because of their lightweight, flexibility, and low fabrication cost. However, the optimization of such OFETs is still in an early stage due to the minimal analytical and numerical models presented in the literature. Objective: This research presses to demonstrate a numerical carrier transport model based on the finite element method (FEM) to investigate the I-V characteristic of OFETs. Methods: Two various organic semiconductor materials have been included in the study, polyaniline and pentacene, where micro-scale, as well as nano-scale models have been presented. OFETs regarding channel length, dielectric thickness, and doping level impact have been studied. We nominated the threshold voltage, the on/off current ratio, the sub-threshold swing, and the field effect mobilities as the primary output evaluating parameters. Results: The numerical model has shown the criticality of the doping effect on tuning the device flowing drain current to exceed 300 μA saturation current, along with a threshold voltage of -0.1 V under a channel length of 30 nm. Conclusion: The study highlights the effectiveness of polyaniline over pentacene as nano-channel length OFET due to the boosted conductivity of polyaniline concerning pentacene.

We have studied a metallic substrate, composed of indium nanodeposits, for metal-enhanced fluorescence (MEF) in the ultraviolet (UV) spectral region. Indium coated slides were prepared using the thermal vapor deposition technique. Theoretical finite difference time domain simulations and experimental studies show that plasmon enhanced absorption and coupled radiation through the scattering component of the extinction spectra of indium nanoparticles, lie in UV region, and are sensitive to the size and density of the nanoparticles, the thickness of the indium film, and polarity of the medium. The MEF effect, measured for intrinsic protein tryptophan and tyrosine residues, loaded onto indium films of different thickness, changes in a wavelike fashion, reflecting changes in the metal film landscape and, consequently, the chromophores coupling with surface plasmons. Indium films also significantly enhance intrinsic fluorescence of proteins themselves [bovine serum albumin]. In this case the wavelength dependence of MEF shows different emission enhancements of protein Tyr and Trp residues. Subsequently, indium-enhanced intrinsic protein fluorescence in the UV spectral region can be of great potential importance for quantitation assays as well as for the labeless detection of biomolecules in the biosciences.

Nanospheres lithography (NSL) is an economical technique, which makes use of highly monodispersed nanospheres such as deposition or etch masks for generating patterns with nanoscale features. Embedding nanostructures into organic electronic devices can endow them with unique capabilities and enhanced performance, which have greatly advanced the development of organic electronics. In this review, a brief summary of the methods for the preparation of monodispersed nanospheres is presented. Afterward, the authors highlight the recent advances of a wide variety of applications of nanospheres lithography in organic electronic devices. Finally, the challenges in this field are pointed out, and the future development of this field is discussed.

Materials Interface Engineering In their Review Article (10.1002/adfm.202515507), Shern-Long Lee and co-workers critically examine the impact of interfacial molecular orientation on organic electronic devices. By modulating the alignment of organic semiconductors at interfaces, fundamental properties such as electrode work function and charge transport pathways can be rationally engineered, thereby optimizing device efficiency and stability. The review provides a holistic perspective, demonstrating that the synergy between experimental synthesis, characterization, and simulation is essential for designing the next generation of high-performance organic electronics.

Insights on the morphology of polymer donor:acceptor blends by optical metrology

Synthesis of n‐type organic semiconductors with high electron mobilities, good environmental stability, and good processability is an urgent task in current organic electronics. This is because most of π‐conjugated materials are p‐type and prefer to transport positive hole carriers. In this article, a series of new dicarboxylic imide‐substituted poly(p‐phenylene vinylenes) (DI‐PPVs) were first synthesized. They exhibited a high electron affinity of 3.60 eV and thus are able to transport electrons. The polymers showed tunable solubility in common organic solvents and high chemical and thermal stability. They remain rigidity of the PPV backbone, and strong interchain π‐stacking was observed in thin films by X‐ray diffraction measurement. All these suggested that these polymers could serve as good candidates as n‐type semiconductors in organic electronic devices such as n‐channel field‐effect transistors and all polymer‐based solar cells. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 186–194, 2010

The highly conductive polymer PEDOT:PSS is a widely used hole transport layer and transparent electrode in organic electronic devices. To date, the mechanical and fracture properties of this conductive polymer layer are not well understood. Notably, the decohesion rate of the PEDOT:PSS layer and its sensitivity to moist environments has not been reported, which is central in determining the lifetimes of organic electronic devices. Here, it is demonstrated that the decohesion rate is highly sensitive to the ambient moisture content, temperature, and mechanical stress. The kinetic mechanisms are elucidated using atomistic bond rupture models and the decohesion process is shown to be facilitated by a chemical reaction between water molecules from the environment and strained hydrogen bonds. Hydrogen bonds are the predominant bonding mechanism between individual PEDOT:PSS grains within the layer and cause a significant loss in cohesion when they are broken. Understanding the decohesion kinetics and mechanisms in these films is essential for the mechanical integrity of devices containing PEDOT:PSS layers and yields general guidelines for the design of more reliable organic electronic devices.

The effect of adding terbium to indium tin oxide (ITO) thin films on the electrical, optical and light emission properties was investigated. The films were prepared by radio frequency dual magnetron sputtering, maintaining a high optical transmittance in the ultraviolet and visible spectral regions, and a low electrical resistivity ranging from 5×10−3 Ω⋅cm to 0.3 Ω⋅cm . Terbium-related luminescence is achieved after annealing at 470 ∘C in air at atmospheric pressure. Electrical resistivity and optical transmittance were measured after each annealing step to evaluate the compromise between the achieved light emission intensity, electrical and optical properties. Additionally, temperature dependence of Tb-related luminescence quenching was assessed by temperature-dependent photoluminescence measurements, from 83 to 533 K, under non-resonant excitation. Thermal quenching activation energies suggest an effective energy transfer mechanism from the ITO host to the rare-earth (RE) ions. This indirect excitation mechanism was modeled using a spherical potential-well and a tight-binding one-band approximation approaches, describing a short-range charge trapping process and subsequent formation of bound excitons to RE ion clusters.

This study analyzed the electronic and optical properties of pentacene derivatives chemically modified by adding nitro and amine groups at different positions on the molecular structure. The study aimed to understand the impact of these modifications on electronic and optical applications, focusing on improving performance in organic electronic devices and solar cells. The results showed that adding nitro groups as electron acceptors and amine groups as electron donors reduces the energy gap and increases the chemical activity of the molecules. It was also observed that changing the positions of these groups significantly affects the polar moment, reflecting changes in the charge distribution within the molecules. In terms of optical properties, the modified molecules showed high light absorption in the visible region of the electromagnetic spectrum, making them promising candidates for organic solar cell applications, where high light absorption efficiency is a prerequisite for these applications. All calculations were performed using the Gaussian 09 software package. The study included molecular geometry optimization using density functional theory (DFT) with the B3LYP hybrid functional and 6-31G(d,p) basis set. Electronic properties, such as the highest occupied molecular orbital HOMO and lowest unoccupied molecular orbital LUMO energy levels, and the energy gap between them were calculated to evaluate the stability and chemical activity. Time-dependent density functional theory (TD-DFT) was used to analyze the optical properties and light absorption. In addition, fixed points were confirmed by vibrational frequency analysis to ensure that the optimized molecular structures represent stable states. The study also included a polar moment calculation to evaluate the effect of chemical modifications on the polarity of the molecules.