A relaxor ferroelectric polymer poly(vinylidene fluoride‐trifluoroethylene‐chlorofloroethylene) exhibits a high relative dielectric constant (k) (∼60). The high‐k polymer is used successfully in solution processable low‐voltage OTFTs as the gate insulator for the first time. Both n‐channel and p‐channel OTFTs based on conjugated polymers are fabricated and show carrier mobilities higher than 0.1 cm2 V−1 s−1 at an operating voltage of 3 V.

Solar steam generation driven by local hot spots is an efficient route to use solar energy. We introduce a novel photoreceiver composed of reduced graphene oxide (rGO) and polyurethane (PU) matrix for highly efficient solar steam generation. The rGO nanosheets covalently cross-linked to PU matrix provide excellent stability and broad optical absorption, together with the property of thermal insulation served by PU resulting in rapid increase of local thermal under illumination. Moreover, the hydrophilic segments and the interconnected pores of rGO/PU can be worked as water channels for replenishment of surface water evaporated. With excellent mechanical and chemical stability, the functional rGO/PU foam exhibited a solar photothermal efficiency of ∼81% at a light density of 10 kW/m 2 . The novel macro design demonstrated here is low cost, simple to prepare, and highly stable, being suitable for a series of practical applications in massive seawater desalination, solar steam generation, and sterilization of waste.

Graphene has attracted much attention in biomedical applications for its fascinating properties. Because of the well-known 2D structure, every atom of graphene is exposed to the environment, so the electronic properties of graphene are very sensitive to charged analytes (ions, DNA, cells, etc.) or an electric field around it, which renders graphene an ideal material for high-performance sensors. Solution-gated graphene transistors (SGGTs) can operate in electrolytes and are thus excellent candidates for chemical and biological sensors, which have been extensively studied in the recent 5 years. Here, the device physics, the sensing mechanisms, and the performance of the recently developed SGGT-based chemical and biological sensors, including pH, ion, cell, bacterial, DNA, protein, glucose sensors, etc., are introduced. Their advantages and shortcomings, in comparison with some conventional techniques, are discussed. Conclusions and challenges for the future development of the field are addressed in the end.

Solar steam generation through heat localization is a new approach to efficiently utilize solar energy. Nanocomposites with noble metals and other porous materials have been employed to generate solar vapor at a high light intensity. However, large-scale applications of the nanocomposites based on noble metals are restricted due to their high cost, complex preparation, and low recycling stability. Herein, we report a simple method toward fabricating graphene aerogel (GA) from graphene oxides only by photoreduction, which is for the first time used to harvest solar energy. GA can not only convert almost the entire incident solar light to heat energy but can also self-float on the surface of water and pump the interface water forming a constant water steam. Solar steam generation efficiencies of 53.6 ± 2.5% and 82.7 ± 2.5% are achieved at light intensities of 1 and 10 kW m–2, respectively. Furthermore, this efficiency is still kept at a high value, and the morphology of GA is hardly broken after 10 cycles of testing. This technology of steam generation through efficiently harvesting solar energy is highly promising for sterilization of waste and seawater desalination.

Defects play significant roles in properties of graphene and related device performances. Most studies of defects in graphene focus on their influences on electronic or luminescent optical properties, while controlling infrared optoelectronic performance of graphene by defect engineering remains a challenge. In the meantime, pristine graphene has very low infrared photoresponses of ~0.01 A/W due to fast photocarrier dynamics. Here we report regulating infrared photoresponses in reduced graphene oxide phototransistors by defect and atomic structure control for the first time. The infrared optoelectronic transport and photocurrent generation are significantly influenced and well controlled by oxygenous defects and structures in reduced graphene oxide. Moreover, remarkable infrared photoresponses are observed in photoconductor devices based on reduced graphene oxide with an external responsivity of ~0.7 A/W, at least over one order of magnitude higher than that from pristine graphene. External quantum efficiencies of infrared devices reach ultrahigh values of ~97%, which to our knowledge is one of the best efficiencies for infrared photoresponses from nonhybrid, pure graphene or graphene-based derivatives. The flexible infrared photoconductor devices demonstrate no photoresponse degradation even after 1000 bending tests. The results open up new routes to control optoelectronic behaviors of graphene for high-performance devices.

Solar steam generation, utilizing abundant solar energy and floating photothermal materials, has been considered as one of the most sustainable, efficient ways to solve the problem of water shortage. Here, a new system for solar steam generation is fabricated based on a PEGylated MoS-cotton cloth (PMoS-CC). 80.5-90 ± 3.5% of high-efficiency solar steam generation is achieved under a light density of 1-5 kW m because of the good gas permeability of CC and the hydrophilic property of PMoS-CC. The self-growth PMoS-CC provides good photothermal performances in pure water and saline water. The water evaporation rate with PMoS-CC keeps a stable value after a long-time illumination (4 h) and 32 times cycle tests. Our result provides a way to prepare pure water in the applications for alleviating a scarcity of drinking water.

Highly sensitive near-infrared (NIR) phototransistors based on poly(3-hexylthiophene) (P3HT) and lead sulfide quantum dots (PbS QDs) were fabricated by a solution process. The phototransistors show high responsivity up to 2 Â 10 4 A W À1 under NIR illumination with wavelength of 895 nm, which is much bigger than that of the photodetectors based on PbS QDs or organic semiconductors only. The sensing mechanism is attributed to the photo-induced electrons generated in the PbS QDs, which increase the threshold voltage of the transistor. These phototransistors may find promising applications as infrared sensors for their high responsivity, easy fabrication, low cost and flexibility.

Organic phototransistors based on a composite of P3HT and TiO 2 nanoparticles have been fabricated, which show high photosensitivity, fast response, and stable performance under both visible and ultraviolet light illumination, and thus they are promising for applications as low cost photosensors. The transfer characteristic of each device exhibits a parallel shift to a positive gate voltage under light illumination, and the channel current increases up to three orders of magnitude in the subthreshold region. The shift in the threshold voltage of the device has a nonlinear relationship with light intensity, which can be attributed to the accumulation of electrons in the embedded TiO 2 nanoparticles. It has been found that the device is extremely sensitive to weak light due to an integration effect. The relationship between the threshold voltage change and the intensity of light illumination can be fitted with a power law. An analytical model has been developed to describe the photosensitive behavior of the devices. It is expected that such organic phototransistors can be developed for sensing different wavelengths based on different semiconducting polymers and semiconducting nanoparticles.