Printable and flexible electronics attract sustained attention for their low cost, easy scale up, and potential application in wearable and implantable sensors. However, they are susceptible to scratching, rupture, or other damage from bending or stretching due to their “soft” nature compared to their rigid counterparts (Si-based electronics), leading to loss of functionality. Self-healing capability is highly desirable for these “soft” electronic devices. Here, a versatile self-healing polymer blend dielectric is developed with no added salts and it is integrated into organic field transistors (OFETs) as a gate insulator material. This polymer blend exhibits an unusually high thin film capacitance (1400 nF cm⁻² at 120 nm thickness and 20–100 Hz). Furthermore, it shows pronounced electrical and mechanical self-healing behavior, can serve as the gate dielectric for organic semiconductors, and can even induce healing of the conductivity of a layer coated above it together with the process of healing itself. Based on these attractive properties, we developed a self-healable, low-voltage operable, printed, and flexible OFET for the first time, showing promise for vapor sensing as well as conventional OFET applications.

A low-voltage operable, highly sensitive, and selectively responsive polymer for the detection of nitroaromatic explosives is investigated. Resistive devices are fabricated by simple spin-coating on flexible and transparent substrates in addition to silicon substrates and are stable under ambient temperature and oxygen levels before exposure to the nitroaromatics. After exposure to 2,4,6-trinitrotoluene (TNT), the devices show increased conductance, even with picogram (pg) quantities of TNT, accompanied by a confirming color change from colorless to deep red. The relative conductance increase per unit exposure is the highest yet reported for TNT. Aromatic anion salts, on the other hand, do not induce any electronic responses. ¹H NMR and microscopic analyses show chemical interactions and morphological changes correlated with the electronic responses, some of which are specific to TNT in relation to other nitroaromatics. The binding constant for the imidazole rings and TNT is on the order of tens of M⁻¹. The materials are promising for rapid indication of exposure to nitroaromatic compounds.

Naphthalenetetracarboxylic diimide derivatives (octyl “8” NTCDI, dimethylaminopropyl “DMP” NTCDI) and copper phthalocyanine (CuPc) are used to form a diverse organic field-effect transistor (OFET) sensor array. CuPc and 8-NTCDI are p-channel and n-channel semiconductors, respectively, showing expected and opposing responses to analytes. DMP-NTCDI, on the other hand, because of its ionizable side chain, shows response directions and magnitudes that are not correlated to those of the other two. The result is a distinct response pattern and unambiguous recognition ability for individual analytes. The differences are even more dramatic if the time evolution of the responses is considered. The three-response patterns obtained from representative polar, nonpolar, acidic, and basic vapors are all different, showing the potential for this approach in rapid, low-cost electronic detection of volatile compounds.

ZnO is a high-mobility electron conductor being considered for high-throughput electronics in flexible and transparent formats. We demonstrated the Zn β-ketoiminate system, based on acetylacetimine with N-propyl, isopropyl, and butyl groups, as a vehicle for preparing ZnO thin films for electronic applications. Surface carbon was a primary impurity, and the precursors studied afforded films with the lowest surface carbon contamination at deposition temperatures near 400°C. Thermal annealing of the films reduced the surface carbon content and afforded semiconducting materials. Annealing also gave larger-grained, better connected films. Thinner films were associated with semiconducting as opposed to ohmic behavior; such films will be adaptable for transparent logic circuits. Copyright © 2012 John Wiley & Sons, Ltd.

Significant progress has been made in designing organic semiconducting materials (OSCs) for the past few decades for organic field-effect transistors (OFETs). Much attention has been paid to the development of p-channel OSCs, with less but highly significant progress on n-channel OSCs. In this review, we focus on the advances made with OFETs in the last few years to achieve high performance in n-channel modes, air stability, and solution processability, leading to printable active electronics. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012

Organic semiconductor films are susceptible to noncovalent interactions, trapping and doping, photoexcitation, and dimensional deformation. While these effects can be detrimental to the performance of conventional circuits, they can be harnessed, especially in field-effect architectures, to detect chemical and physical stimuli. This Review summarizes recent advances in the use of organic electronic materials for the detection of environmental chemicals, pressure, and light. The material features that are responsible for the transduction of the input signals to electronic information are discussed in detail.

N,N′-bis(3-(perfluoroctyl)propyl)-1,4,5,8-naphthalenetetracarboxylic acid diimide (8–3-NTCDI) was newly synthesized, as were related fluorooctylalkyl-NTCDIs and alkyl-NTCDIs. The 8–3-NTCDI-based organic thin-film transistor (OTFT) on an octadecyltrimethoxysilane (OTS)-treated Si/SiO₂ substrate shows apparent electron mobility approaching 0.7 cm² V^-1s^-1 in air. The fluorooctylethyl-NTCDI (8–2-NTCDI) and fluorooctylbutyl-NTCDI (8–4-NTCDI) had significantly inferior properties even though their chemical structures are only slightly different, and nonfluorinated decyl and undecyl NTCDIs did not operate predictably in air. From atomic force microscopy, the 8–3-NTCDI active layer deposited with the substrate at 120 °C forms a polycrystalline film with grain sizes >4μm. Mobilities were stable in air for one week. After 100 days in air, the average mobility of three OTFTs decreased from 0.62 to 0.12 cm² V^-1s^-1, but stabilized thereafter. The threshold voltage (V_T) increased by 15 V in air, but only by 3 V under nitrogen, after one week. On/off ratios were stable in air throughout. We also investigated transistor stability to gate bias stress. The transistor on hexamethlydisilazane (HMDS) is more stable than that on OTS with mobility comparable to amorphous Si TFTs. V_T shifts caused by ON (30 V) and OFF (–20 V) gate bias stress for the HMDS samples for 1 hour were 1.79 V and 1.27 V under N₂, respectively, and relaxation times of 10⁶ and 10⁷ s were obtained using the stretched exponential model. These performances are promising for use in transparent display backplanes.