Advanced micro/nano-flexible sensors, displays, electronic skins, and other related devices provide considerable benefits compared to traditional technologies, aiding in the compactness of devices, enhancing energy efficiency, and improving system reliability. The creation of cost-effective, scalable, and high-resolution fabrication techniques for micro/nanostructures built from optoelectronic materials is crucial for downsizing to enhance overall efficiency and boost integration density. The electrohydrodynamic jet (EHD) printing technology is a novel additive manufacturing process that harnesses the power of electricity to create fluid motion, offering unparalleled benefits and a diverse spectrum of potential uses for microelectronic printing in terms of materials, precision, accuracy, and cost-effectiveness. This article summarizes various applications of EHD printing by categorizing them as zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) printing materials. Zero-dimensional (quantum dot) materials are predominantly utilized in LED applications owing to their superb optoelectronic properties, high color fidelity, adjustable color output, and impressive fluorescence quantum yield. One- and two-dimensional materials are primarily employed in FET and sensor technologies due to their distinctive physical structure and exceptional optoelectronic properties. Three-dimensional materials encompass nanometals, nanopolymers, nanoglass, and nanoporous materials, with nanometals and nanopolymers finding widespread application in EHD printing technology. We hope our work will facilitate the development of small-feature-size, large-scale flexible electronic devices via EHD printing.

In this study, 6,13-bis(triisopropylsilylethynyl) (TIPS) pentacene crystalline growth was enhanced using temperature gradient across the substrate. This method induced a preferential crystal orientation in order to alleviate the intrinsic crystallization anisotropy and control film morphology. The temperature gradient led to a solubility difference along the substrate and drove crystallization from the lower-temperature end to the higher. The approach also enables a methodical investigation of how TIPS pentacene crystal morphology depends on temperature. The resulting TIPS pentacene film exhibited a uniform morphology and high percentage of large areal coverage. X-ray diffraction characterization showed that the film crystallinity was not sacrificed when a temperature gradient is applied. The authors demonstrated that organic thin film transistors (OTFTs) based on TIPS pentacene crystals grown using the temperature-gradient method significantly enhanced average mobility when compared to OTFTs using films grown without the temperature gradient.

In recent years, the charge carrier mobility study of organic semiconductors has seen significant progress and surpassed that of amorphous silicon thanks to the development of various molecular engineering, solution processing, and external alignment methods. These advances have allowed the implementation of organic semiconductors for fabricating high-performance organic electronic devices. In particular, diketopyrrolopyrrole-based small-molecular and polymeric organic semiconductors have garnered considerable research interest due to their ambipolar charge-carrier properties. In this article, we focus on conducting a comprehensive review of previous studies that are dedicated to the external alignment, thermal annealing, and molecular engineering of diketopyrrolopyrrole molecular structures and side-chain structures in order to achieve oriented crystal orientation, optimized thin-film morphology, and enhanced charge carrier transport. By discussing these benchmark studies, this work aims to provide general insights into optimizing other high-mobility, solution-processed organic semiconductors and sheds lights on realizing the acceleration of organic electronic device applications.

Grain boundaries are among the most influential structural features that control the charge transport in polycrystalline organic semiconductors. Acting as both charge trapping sites and electrostatic barriers, they disrupt molecular packing and introduce energetic disorder, thereby limiting carrier mobility, increasing threshold voltage, and degrading the stability of organic thin-film transistors (OTFTs). This review presents a detailed discussion of grain boundary formation, their impact on charge transport, and experimental strategies for engineering their structure and distribution across several high-mobility small-molecule semiconductors, including pentacene, TIPS pentacene, diF-TES-ADT, and rubrene. We explore grain boundary engineering approaches through solvent design, polymer additives, and external alignment methods that modulate crystallization dynamics and domain morphology. Then various case studies are discussed to demonstrate that optimized processing can yield larger, well-aligned grains with reduced boundary effects, leading to great mobility enhancements and improved device stability. By offering insights from structural characterization, device physics, and materials processing, this review outlines key directions for grain boundary control, which is essential for advancing the performance and stability of organic electronic devices.

Organic electronics represent a promising frontier in the research and development of flexible, lightweight, and cost-effective electronic devices. However, their broader adoption is currently impeded by several critical challenges, including material stability, low charge carrier mobility, difficulties in controlling crystallization and morphology, and overall device reliability. This article provides a detailed analysis of these challenges, and discusses how they affect the performance and longevity of organic electronic devices. It then explores the incorporation of polystyrene (PS) as a polymer additive, highlighting its effectiveness in mitigating these issues. PS, when blended with organic semiconductor materials, has been shown to significantly enhance device performance by improving molecular ordering, reducing defect density, and stabilizing interfaces. In thin film transistors, PS contributes to better mechanical stability and higher charge carrier mobility by promoting favorable phase segregation and crystallization. In phototransistors and sensors, PS enhances sensitivity and selectivity while also improving environmental resistance. Additionally, in memory devices, PS facilitates better charge storage and retention characteristics. This article underscores the critical role of PS in advancing organic electronics, and demonstrates how its strategic use can overcome some of the most persistent challenges in the field, paving the way for unlocking the full potential of organic electronic devices in commercial applications.