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This study rigorously investigated the impact of asymmetric side chain design on the performance of organic electrochemical transistors (OECTs). Hydrophilic and hydrophobic side chains were systematically introduced into poly(isoindigo-bithiophene)-based polymers, and the resulting symmetric and asymmetric side chain combinations were carefully compared. The objective was to enhance coplanarity, mobility, hydrophilicity, and stability to improve OECT device performance. While P(C,C) and P(O,O), with symmetric branched alkyl and oligoether side chains, exhibit effective OECT device functions, the asymmetric side-chain designed P(C,O), with branched alkyl and oligoether side chains, outperforms both symmetric counterparts. P(C,O) demonstrates OECT performance with a pronounced product of mobility and capacitance (μhC*) of 65.2 F cm−1 V−1 s−1, excellent hole mobility (μh) of 0.78 cm2 V−1 s−1, and fast response speed. Specifically, P(C,O) demonstrates superior stability while maintaining good capacitance. The performance retention of P(C,O) after consecutive ON/OFF cycles is 77.5%, which is much higher than 35.2% and 47.0% of P(C,C) and P(O,O). The asymmetric structure contributes to enhancing coplanarity and structural stability, resulting in improved crystalline properties after electrolyte swelling. This study presents a balanced and rigorous approach to balancing the performance and stability in OECTs through asymmetric side chain design. [ABSTRACT FROM AUTHOR]

Stretchable conjugated polymers with conjugation break spacers (CBSs) synthesized via random terpolymerization have gained considerable attention because of their efficacy in modulating mobility and stretchability. This study incorporates a series of dianhydrohexitol diastereomers of isosorbide (ISB) and isomannide (IMN) units into the diketopyrrolopyrrole‐based backbone as CBSs. It is found that the distorted CBS (IMN) improves the mobility–stretchability properties of the polymer with a highly coplanar backbone, whereas the extended CBS (ISB) enhances those of the polymer with a noncoplanar backbone. Additionally, the different configurations of ISB and IMN sufficiently affect the solid‐state packing, aggregation capabilities, crystallographic parameters, and mobility–stretchability properties of the polymer. The IMN‐based polymers exhibit the highest mobility of 1.69 cm2 V−1 s−1 and crystallinity retentions of (85.7, 78.6)% under 20% and 60% strains, outperforming their ISB‐based or unmodified counterparts. The improvement is correlated with a robust aggregation capability. Furthermore, the CBS content affects aggregation behavior, notably affecting mobility. This result indicates that incorporating CBSs into the polymer can enhance backbone flexibility via movement and rotation of the CBS without affecting the crystalline regions. [ABSTRACT FROM AUTHOR]

Polyimides (PIs) are widely used materials due to their high thermal stability and potentially low dielectric constant (Dk) and dissipation factor (Df). However, Dk and Df values tend to increase at higher frequencies. Therefore, there is a significant need to reduce the Dk and Df values of PIs, which is the main purpose of this study. This research considers multiple factors, including the ring structures and conjugations on the conformation of the PI backbone. The effects of five‐membered and six‐membered PIs and the conjugated length of benzene and naphthalene structures in the repeating units on the thermomechanical and dielectric properties are systematically investigated. As a result, the PI with a six‐membered imide contributes to higher thermal stability, with a glass transition temperature higher than 350 °C, a thermal decomposition point of 529 °C, and a lower Dk of 2.7–2.8. Still, it exhibits a lower molecular weight than that of a five‐membered imide. On the other hand, PIs with esterified structures show an extremely low Df value, 0.002–0.005. This situation can be attributed to the vital correlation between the Df and the volumetric dipole moment. This study also presents the different properties arising from ring structures and conjugations. Meanwhile, the relationships between Dk and volumetric polarizability and between Df and volumetric dipole moment are confirmed. This work provides a guideline for the structure−dielectric relationship of PI at a high frequency of 10–40 GHz. [ABSTRACT FROM AUTHOR]

Quasi‐2D(two dimentional) perovskite is one of the potential materials in optoelectronic applications due to the scalable solution processes and low binding energy. Recent studies employing diverse spacer ligands of mono‐ and di‐amine functional groups to form Ruddlesden‐Popper (RP) and Dion‐Jacobson (DJ) phase perovskites efficiently manipulate the perovskite microstructure. However, there is a notable gap in investigating the performance of photomemory devices based on perovskites using different ligands and the accommodability in polymer matrixes. Herein, the perovskite with phenethylammonium bromide (PEABr) or p‐xylylenediamine (PDMA) ligands and methacrylate polymers comprising varied pendent groups (benzene and pyrene) are designed to investigate their effect. The results show that RP‐phase perovskite with polymer‐conferred pyrene group presented an excellent crystalline orientation, fewer grain boundaries, and higher charge transfer efficiency, attributed to superior accommodation between ligands and polymers and appropriate aggregation of pyrene groups. It demonstrates superior memory device characteristics of a high ON/OFF current ratio (2.68 × 104), low operational voltage (−0.1 V), short illumination times (0.1 s), and maintains its decent performance even under thermal environments. This work highlights that leveraging the steric hindrance of ligands and functional polymers to control the microstructure of perovskite is a prospective strategy to promote the photomemory's development. [ABSTRACT FROM AUTHOR]

The escalating environmental impact of pollution and the imperative to reduce carbon emissions have heightened the significance of developing biobased materials from natural biomass for electronic devices. This study investigates the utilization of biofermentation‐produced recombinant spider silk and animal‐derived hemin to create a novel biobased electret for field‐effect transistor memory. A critical challenge arises from the incompatibility between natural photoresponsive molecules and insulating biomaterials, resulting in severe phase separation that compromises film quality and morphology uniformity. This study systematically examines the effects of various film deposition and manufacturing techniques on the biobased electret's morphology, phase separation, and performance. Different methods demonstrate distinct advantages in terms of molecular aggregation/segregation, morphological homogeneity, and device performance. Phototransistor memory devices fabricated using spin coating and spray coating techniques exhibit robust aggregations and high memory windows of ≈30 V. Conversely, devices produced through solution shearing and electrospinning methods display enhanced smooth morphologies and high photoresponsivity. The phototransistor memory comprising electrospun fibers holds the potential to achieve the highest memory ratio, reaching ≈105. These findings not only highlight the applications of biobased materials through scalable film deposition processes but also underscore the importance of refining their morphology, phase separation, and performance in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Artificial synapses have gained great interest in the past few years because of their importance in deep learning and image recognition. To fulfill device miniaturization and reduce the energy consumption of device operation, a series of silane‐based photoactive/conjugated self‐assembled molecules (CSAMs), including isoindigo (IID), diketopyrrolopyrrole, and benzodithiophene, are used as the charge‐trapping layers in synaptic phototransistors. The devices comprising CSAM demonstrate excellent short‐term/long‐term memory behaviors and can emulate the paired‐pulse facilitation (PPF) function. Notably, the IID‐based device shows the highest photoresponse, and this performance is highly related to the charge transfer efficiency and the photophysics lifetimes derived from the time‐resolved photoluminescence and the transient absorption characterizations. Therefore, IID produces the highest PPF ratios of 139% to blue light and 144% to green light. In addition, the energy consumption of 0.029 fJ at an operating voltage of −0.1 mV is achieved, which is the lowest value in synaptic phototransistors so far. Notably, neural networks of supervised and unsupervised learning algorithms are demonstrated in the device studied to process a pattern recognition system. Collectively, using conjugated self‐assembled materials as a charge‐trapping layer is a promising way for synaptic phototransistor applications to reduce energy consumption and fulfill the device miniaturization. [ABSTRACT FROM AUTHOR]

Photodetectors are one of the most essential optoelectronics nowadays. Perovskites have emerged as one of the potential materials for photodetectors due to their high absorption efficiency over a wide range of wavelengths, high charge mobility, strong mechanical deformability, and solution processability. In this study, interfacial engineering using self‐assembled monolayers (SAMs) is explored to improve the performance of perovskite photodetectors. SAMs with different terminal groups exhibit distinct surface energy, and they all result in a reduced exciton lifetime of the perovskite due to charge transfer between polycrystalline perovskite and the SAMs. In particular, the photodetector modified with (4‐hydroxyphenyl)phosphonic acid (OH) exhibits the highest electron mobility of 0.8 cm2 V−1 s−1 under 450‐nm light illumination. In addition, it shows excellent detector performance with an ultrafast photoresponse of < 14 ms, a high photoresponsivity of 5600 AW−1, and a high specific detectivity of 5.9 × 1010 Jones at a low light intensity of 18 µW cm−2. The excellent photoresponse and device switchability are attributed to the high surface energy of OH, the resulting homogeneous perovskite film morphology, the high charge transfer efficiency, and the favorable energy level alignment. The studies provide new prospects for the development of emerging perovskite photodetectors. [ABSTRACT FROM AUTHOR]

Recently, there has been growing interest among researchers in developing efficient photorecording devices using perovskite (PVSK) materials as floating gate layers due to their simplified structure and noncontact, light-responsive characteristics. Since a PVSK-based memory layer can reduce the operating voltage of the device, it can be used for nonvolatile memory applications. Herein, the p-type material pentacene was utilized as the charge transport layer, while methylammonium lead bromide PVSK nanocrystals (NCs) were employed as the floating gate memory layer. Four types of poly-(amic acid) (PAA) polymers were synthesized in combination with PVSK for the memory layer. Compared to conventional polymers, PAA can further fine-tune the influence of energy-level alignment and the crystalline structure of PVSK NCs. The PAA structure consists of carboxylic acid and amide groups that can form Lewis acid–base interactions with PVSK NCs, while these hydrogen-bonding groups can interact with methylammonium to confine crystallite size, thereby passivating defects in PVSK NC films, providing structural stability and effectively optimizing device performance. Among the four synthesized PAA structures, sulfonyldianiline-cyclobutanetetracarboxylic dianhydride (SODA-CBDA) had a sulfone group and cyclobutane ring, possessing electron-withdrawing abilities that lowered the highest occupied molecular orbital level and a conjugation breaker that raised the lowest unoccupied molecular orbital level, resulting in a wider bandgap and stabilized electrons and holes compared to the other PAA structures. The fabricated device required only 1 s to complete electrical erasing and exhibited a stable and high ON/OFF current ratio (∼104) and long-term stability (>104 s) over consecutive device operations. [ABSTRACT FROM AUTHOR]

Up to now, researches on the mobility–stretchability of semiconducting polymers are extensively investigated, but little attention was paid to their morphology and field‐effect transistor characteristics under compressive strains, which is equally crucial in wearable electronic applications. In this work, a contact film transfer method is applied to evaluate the mobility–compressibility properties of conjugated polymers. A series of isoindigo–bithiophene conjugated polymers with symmetric carbosilane side chains (P(SiSi)), siloxane‐terminated alkyl side chains (P(SiOSiO)), and combined asymmetric side chains (P(SiOSi)) are investigated. Accordingly, a compressed elastomer slab is used to transfer and compress the polymer films by releasing prestrain, and the morphology and mobility evolutions of these polymers are tracked. It is found that P(SiOSi) outperforms the other symmetric polymers including P(Si─Si) and P(SiO─SiO), having the ability to dissipate strain with its shortened lamellar spacing and orthogonal chain alignment. Notably, the mechanical durability of P(SiOSi) is also enhanced after consecutive compress–release cycles. In addition, the contact film transfer technique is demonstrated to be applicable to investigate the compressibility of different semiconducting polymers. These results demonstrate a comprehensive approach to understand the mobility–compressibility properties of semiconducting polymers under tensile and compressive strains. [ABSTRACT FROM AUTHOR]