Biocompatible/Degradable Silk Fibroin:Poly(Vinyl Alcohol)-Blended Dielectric Layer Towards High-Performance Organic Field-Effect Transistor

Recent Advances in Biomolecule-Nanomaterial Heterolayer-Based Charge Storage Devices for Bioelectronic Applications

With the acceleration of the Fourth Industrial Revolution, the development of information and communications technology requires innovative information storage devices and processing devices with low power and ultrahigh stability. Accordingly, bioelectronic devices have gained considerable attention as a promising alternative to silicon-based devices because of their various applications, including human-body-attached devices, biomaterial-based computation systems, and biomaterial-nanomaterial hybrid-based charge storage devices. Nanomaterial-based charge storage devices have witnessed considerable development owing to their similarity to conventional charge storage devices and their ease of applicability. The introduction of a biomaterial-to-nanomaterial-based system using a combination of biomolecules and nanostructures provides outstanding electrochemical, electrical, and optical properties that can be applied to the fabrication of charge storage devices. Here, we describe the recent advances in charge storage devices containing a biomolecule and nanoparticle heterolayer including (1) electrical resistive charge storage devices, (2) electrochemical biomemory devices, (3) field-effect transistors, and (4) biomemristors. Progress in biomolecule-nanomaterial heterolayer-based charge storage devices will lead to unprecedented opportunities for the integration of information and communications technology, biotechnology, and nanotechnology for the Fourth Industrial Revolution.

Building memory devices from biocomposite electronic materials

Natural biomaterials are potential candidates for the next generation of green electronics due to their biocompatibility and biodegradability. On the other hand, the application of biocomposite systems in information storage, photoelectrochemical sensing, and biomedicine has further promoted the progress of environmentally benign bioelectronics. Here, we mainly review recent progress in the development of biocomposites in data storage, focusing on the application of biocomposites in resistive random-access memory (RRAM) and field effect transistors (FET) with their device structure, working mechanism, flexibility, transient characteristics. Specifically, we discuss the application of biocomposite-based non-volatile memories for simulating biological synapse. Finally, the application prospect and development potential of biocomposites are presented.

Application of Biodegradable and Biocompatible Nanocomposites in Electronics: Current Status and Future Directions

With the continuous increase in the production of electronic devices, large amounts of electronic waste (E-waste) are routinely being discarded into the environment. This causes serious environmental and ecological problems because of the non-degradable polymers, released hazardous chemicals, and toxic heavy metals. The appearance of biodegradable polymers, which can be degraded or dissolved into the surrounding environment with no pollution, is promising for effectively relieving the environmental burden. Additionally, biodegradable polymers are usually biocompatible, which enables electronics to be used in implantable biomedical applications. However, for some specific application requirements, such as flexibility, electric conductivity, dielectric property, gas and water vapor barrier, most biodegradable polymers are inadequate. Recent research has focused on the preparation of nanocomposites by incorporating nanofillers into biopolymers, so as to endow them with functional characteristics, while simultaneously maintaining effective biodegradability and biocompatibility. As such, bionanocomposites have broad application prospects in electronic devices. In this paper, emergent biodegradable and biocompatible polymers used as insulators or (semi)conductors are first reviewed, followed by biodegradable and biocompatible nanocomposites applied in electronics as substrates, (semi)conductors and dielectrics, as well as electronic packaging, which is highlighted with specific examples. To finish, future directions of the biodegradable and biocompatible nanocomposites, as well as the challenges, that must be overcome are discussed.

Effect of Vertical Annealing on the Nitrogen Dioxide Response of Organic Thin Film Transistors

Nitrogen dioxide (NO₂) sensors based on organic thin-film transistors (OTFTs) were fabricated by conventional annealing (horizontal) and vertical annealing processes of organic semiconductor (OSC) films. The NO₂ responsivity of OTFTs to 15 ppm of NO₂ is 1408% under conditions of vertical annealing and only 72% when conventional annealing is applied. Moreover, gas sensors obtained by vertical annealing achieve a high sensing performance of 589% already at 1 ppm of NO₂, while showing a preferential response to NO₂ compared with SO₂, NH₃, CO, and H₂S. To analyze the mechanism of performance improvement of OTFT gas sensors, the morphologies of 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) films were characterized by atomic force microscopy (AFM) in tapping mode. The results show that, in well-aligned TIPS-pentacene films, a large number of effective grain boundaries inside the conducting channel contribute to the enhancement of NO₂ gas sensing performance.

Human Hair Keratin for Biocompatible Flexible and Transient Electronic Devices

Biomaterials have been attracting attention as a useful building block for biocompatible and bioresorbable electronics due to their nontoxic property and solution processability. In this work, we report the integration of biocompatible keratin from human hair as dielectric layer for organic thin-film transistors (TFTs), with high performance, flexibility, and transient property. The keratin dielectric layer exhibited a high capacitance value of above 1.27 μF/cm² at 20 Hz due to the formation of electrical double layer. Fully solution-processable TFTs based on p-channel poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b]dithiophen-2-yl)-alt[1,2,5]thiadiazolo[3,4-c]-pyridine] (PCDTPT) and keratin dielectric exhibited high electrical property with a saturation field-effect mobility of 0.35 cm²/(Vs) at a low gate bias of -2 V. We also successfully demonstrate flexible TFTs, which exhibited good mechanical flexibility and electrical stability under bending strain. An artificial electronic synaptic PCDTPT/keratin transistor was also realized and exhibited high-performance synaptic memory effects via simple operation of proton conduction in keratin. An added functionality of using keratin as a substrate was also presented, where similar PCDTPT TFTs with keratin dielectric were built on top of keratin substrate. Finally, we observed that our prepared devices can be degraded in ammonium hydroxide solution, establishing the feasibility of keratin layer as various components of transient electrical devices, including as a substrate and dielectric layer.

Effect of In Situ Annealing Treatment on the Mobility and Morphology of TIPS-Pentacene-Based Organic Field-Effect Transistors

In this work, organic field-effect transistors (OFETs) with a bottom gate top contact structure were fabricated by using a spray-coating method, and the influence of in situ annealing treatment on the OFET performance was investigated. Compared to the conventional post-annealing method, the field-effect mobility of OFET with 60 °C in situ annealing treatment was enhanced nearly four times from 0.056 to 0.191 cm²/Vs. The surface morphologies and the crystallization of TIPS-pentacene films were characterized by optical microscope, atomic force microscope, and X-ray diffraction. We found that the increased mobility was mainly attributed to the improved crystallization and highly ordered TIPS-pentacene molecules.