We present a scalable and facile technique for noncovalent functionalization of graphene with 1-pyrenecarboxylic acid that exfoliates single-, few-, and multilayered graphene flakes into stable aqueous dispersions. The exfoliation mechanism is established using stringent control experiments and detailed characterization steps. Using the exfoliated graphene, we demonstrate highly sensitive and selective conductometric sensors (whose resistance rapidly changes >10,000% in saturated ethanol vapor), and ultracapacitors with extremely high specific capacitance (∼ 120 F/g), power density (∼ 105 kW/kg), and energy density (∼ 9.2 Wh/kg).

A Josephson junction defect spectrometer for measuring two-level systems Appl. Phys. Lett. 101, 062602 (2012) Resistive switching by migration of hydrogen ions Appl. Phys. Lett. 101, 043507 (2012) Nonlinear induction detection of electron spin resonance Appl. Phys. Lett. 101, 022602 (2012) Identifying capacitive and inductive loss in lumped element superconducting hybrid titanium nitride/aluminum resonators Appl.

We report here the field emission studies of a layered WS2-RGO composite at the base pressure of ~1 × 10−8 mbar. The turn on field required to draw a field emission current density of 1 μA/cm2 is found to be 3.5, 2.3 and 2 V/μm for WS2, RGO and the WS2-RGO composite respectively. The enhanced field emission behavior observed for the WS2-RGO nanocomposite is attributed to a high field enhancement factor of 2978, which is associated with the surface protrusions of the single-to-few layer thick sheets of the nanocomposite. The highest current density of ~800 μA/cm2 is drawn at an applied field of 4.1 V/μm from a few layers of the WS2-RGO nanocomposite. Furthermore, first-principles density functional calculations suggest that the enhanced field emission may also be due to an overalp of the electronic structures of WS2 and RGO, where graphene-like states are dumped in the region of the WS2 fundamental gap.

A two-step process for synthesizing stable Cs 2 SnI 6 perovskite thin films is reported in this letter. The two-step process includes the co-evaporation of two precursors SnI 2 and CsI onto a glass substrate, followed by a post thermal annealing process in iodine vapor. Using this technique, pure Cs 2 SnI 6 perovskite thin films were successfully synthesized without any wet process. These perovskite thin films are found to be stable under ambient conditions. They also show an electron mobility up to 509 cm 2 V −1 s −1 , which is higher than the mobilities of films prepared by solution processes reported in the literature. IMPACT STATEMENTA novel two-step dry process to synthesize phase-pure, air-stable Cs 2 SnI 6 perovskite thin film with higher electron mobility than that of the films prepared by the solution process.

We present fabrication and characterization of macroscopic thin films of graphene flakes, which are functionalized with 1-pyrenecarboxylic acid (PCA) and are laminated onto flexible and transparent polydimethylsiloxane (PDMS) membranes. The noncovalently (π-stacked) functionalization of PCA allows us to obtain a number of unique optical and molecular sensing properties that are absent in pristine graphene films, without sacrificing the conducting nature of graphene. The flexible PCA-graphene-PDMS hybrid structure can block 70-95% of ultraviolet (UV) light, while allowing 65% or higher transmittance in the visible region, rendering them potentially useful for a number of flexible UV absorbing/filtering applications. In addition, the electrical resistance of these structures is found to be sensitive to the illumination of visible light, atmospheric pressure change, and the presence of different types of molecular analytes. Owing to their multifunctionality, these hybrid structures have immense potential for the development of versatile, low-cost, flexible, and portable electronic and optoelectronic devices for diverse applications.