Lead sulfide (PbS) quantum dots (QDs) have great potential in optoelectronic applications because of their desirable characteristics as a light absorber for near-infrared (NIR) photodetection. However, most PbS-based NIR photodetectors are two-terminal devices, which require an integrated pixel circuit to be practical photosensors. Here we report on PbS QD/indium gallium zinc oxide (InGaZnO, IGZO) metal oxide semiconductor hybrid phototransistors with a photodetection capability between 700 and 1400 nm, a range that neither conventional Si nor InGaAs photodetectors can cover. The new hybrid phototransistor exhibits excellent photoresponsivity of over 10 6 A W − 1 and a specific detectivity in the order of 10 13 Jones for NIR (1000 nm) light. Furthermore, we demonstrate an NIR (1300 nm) imager using photogating inverter pixels based on PbS/IGZO phototransistors at an imaging frequency of 1 Hz with a high output voltage photogain of~4.9 V (~99%). To the best of our knowledge, this report demonstrates the first QD/metal oxide hybrid phototransistor-based flat panel NIR imager. Our hybrid approach using QD/metal oxide paves the way for the development of gate-tunable and highly sensitive flat panel NIR sensors/ imagers that can be easily integrated.

DNA-base small molecules of guanine, cytosine, adenine, and thymine construct the DNA double helix structure with hydrogen bonding, and they possess such a variety of intrinsic benefits as natural plentitude, biodegradability, biofunctionality, low cost, and low toxicity. On the basis of these advantages, here, we report on unprecedented useful applications of guanine layer as hydrogen getter and charge trapping layer when it is embedded into a dielectric oxide of n-channel inorganic InGaZnO and p-channel organic heptazole field effect transistors (FETs). The embedded guanine layer much improved the gate stability of inorganic FETs gettering many hydrogen atoms in the gate dielectric layer of FET, and it also played as charge trapping layer to which the voltage pulse-driven charges might be injected from channel, resulting in a threshold voltage (Vth) shift of FETs. Such shift state is very ambient-stable and almost irrevocable even under a high electric-field at room temperature. So, Boolean logics are nicely demonstrated by using our FETs with the guanine-embedded dielectric. The original Vth is recovered only under high energy blue photons by opposite voltage pulse (charge-ejection), which indicates that our device is also applicable to nonvolatile photo memory.

To enhance the mechanical strength of poly(ethylene glycol)(PEG) gels and to provide functional groups for surface modification, we prepared interpenetrating (IPN) hydrogels by incorporating poly(2-hydroxyethyl methacrylate)(PHEMA) inside PEG hydrogels. Formation of IPN hydrogels was confirmed by measuring the weight percent gain of the hydrogels after incorporation of PHEMA, as well as by ATR/FTIR analysis. Synthesis of IPN hydrogels with a high PHEMA content resulted in optically transparent and extensively crosslinked hydrogels with a lower water content and a 6 $ 8-fold improvement in mechanical properties than PEG hydrogels. Incorporation of less than 90 wt % PHEMA resulted in opaque hydrogels due to phase separation between water and PHEMA. To overcome the poor cell adhesion properties of the IPN hydrogels, collagen was covalently grafted to the surface of IPN hydrogels via carbamate linkages to hydroxyl groups in PHEMA. Resultant IPN hydrogels were proven to be noncytotoxic and cell adhesion study revealed that collagen immobilization resulted in a significant improvement of cell adhesion and spreading on the IPN hydrogel surfaces. The resultant IPN hydrogels were noncytotoxic, and a cell adhesion study revealed that collagen immobilization improved cell adhesion and spreading on the IPN hydrogel surfaces significantly. These results indicate that PEG/PHEMA IPN hydrogels are highly promising biomaterials that can be used in artificial corneas and a variety of other load-bearing tissue engineering applications.

A non‐classical organic strain gauge as a voltage signal sensor is reported, using an inverter‐type thin‐film transistor (TFT) circuit, which is able to sensitively measure a large quantity of elastic strain (up to ≈2.48%), which approaches an almost folding state. Novel heptazole‐based organic TFTs are chosen to be incorporated in this gauge circuit; organic solid heptazole has small domain size in general. While large crystal domain‐pentacene TFTs seldom show sufficient current variation upon mechanical bending for tensile strain, these heptazole TFTs demonstrate a significant variation for the same strain condition as applied to pentacene devices. In addition, the pentacene channel does not recover to its original electric state after bending but heptazole channels are very elastic and reversible, even after going through serious bending. More interesting is that the heptazole TFTs show only a little variation of signal current under horizontal direction strain, while they make a significant amount of current decrease under vertical direction strain. Utilizing the anisotropic response to the tensile bending strain, an ultrasensitive voltage output strain gauge composed of a horizontally and vertically oriented TFT couple is demonstrated.

Stretchable electronic devices should be enabled by the smart design of materials and architectures because their commercialization is limited by the tradeoff between stretchability and electrical performance limits. In this study, thin‐film transistors are fabricated using strategies that combine the unit process of a novel hybrid gate insulator and low‐temperature indium gallium tin oxide (IGTO) channel layer and a stress‐relief substrate structure. Novel hybrid dielectric films are synthesized and their molecular structural configurations are analyzed. These films consist of a polymer [poly(4‐vinylphenol‐co‐methylmethacrylate)], cross‐linkers having different binding structures [1,6‐bis(trimethoxysilyl)hexane (BTMSH), dodecyltrimethoxysilane, and poly(melamine‐co‐formaldehyde)], and an inorganic zirconia component (ZrOx). The hybrid film with BTMSH cross‐linker and 0.2 M ZrOx exhibits excellent insulating properties as well as mechanical stretchability. IGTO transistors fabricated on polyimide‐coated glass substrates are transferred to the rubber substrate to offer stretchability of the transistor pixelated thin‐film transistors. IGTO transistors fabricated on stretchable substrates using these strategies show promising electrical performance and mechanical durability. After 200 stretchability test cycles under uniaxial elongation of approximately 300%, the IGTO transistor still retains a high carrier mobility of 21.7 cm2 V−1 s−1, a low sub‐threshold gate swing of 0.68 V decade−1 and a high ION/OFF ratio of 2.0 × 107.