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ACS Appl Mater Interfaces ; 11(12): 11749-11754, 2019 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-30807098


A differentiator is an electronic component used to accomplish mathematical operations of calculus functions of differentiation for shaping different waveforms. Differentiators are used in numerous areas of electronics, including electronic analog computers, wave-shaping circuits, and frequency modulators. Conventional differentiators are fabricated using active operational amplifiers or using passive resistor-capacitor combinations. Here, we report that a single Cu2S-CdS heterostructure acts as a differentiator for performing numerical functions of input waveform conversion into different shapes. When a rectangular wave signal is applied through the tip of a conductive atomic force microscope, a spikelike wave signal is obtained from the Cu2S-CdS heterostructure. The Cu2S-CdS differentiator is able to convert a sine wave signal into a cosine wave signal and a triangular wave signal into a square wave signal similar to the classical differentiators. The finding of a nanoscale differentiator at extremely small length scales may have profound applications in different domains of electronics.

J Nanosci Nanotechnol ; 18(3): 1741-1746, 2018 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-29448653


We report on a flexible triboelectric nanogenerator (FTENG) designed using polydimethylsiloxane (PDMS) and aluminium (Al) combinations to convert ambient mechanical energy into electrical outputs. An open-circuit output voltage of ~40 V and short-circuit current density of ~63.6 mA m-2 with power density 0.62 W m-2 was easily obtained from the FTENG. The harvested mechanical energy is used for lighting ~100 light emitting diodes and to operate seven segment display enabling prospects for carbon-emission free environment friendly source for powering portable electronic devices. We have shown the capability of using the FTENG as self-powered weight and pressure sensors. Additionally, flexible design of the FTENG extends its application scope for self-powered tactile sensing in electronic skin for robotic application. The FTENG is simply designed, cost-effective, scalable and high-throughput for possible uses in flexible electronics, self-powered systems and body sensor networks.

Small ; 13(15)2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28134490


Aggregation-induced emission (AIE) is commonly observed in irregular bulk form. Herein, unique aggregation properties of an AIE-active complex into branched supramolecular wires are reported for the first time. Mono-cyclometalated Ir(III) complex shows in-plane J-aggregation at the air-water interface owing to the restriction of intramolecular vibration of bidentate phenylpyridinato and intramolecular rotations of monodentate triphenylphosphine ligands at air-water interface. As a consequence, a large enhancement of luminescence comparable to the solid state is obtained from the monolayers of supramolecular wires. This unique feature is utilized for the fabrication of light-emitting diodes with low threshold voltage using supramolecular wires as active layer. This study opens up the need of ordered assembly of AIE complexes to achieve optimal luminescence characteristics.

Phys Chem Chem Phys ; 17(12): 8159-65, 2015 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-25728482


We report on the direct observation of ferroelectric switching and piezoelectric behaviour in ultrathin polyvinylidene fluoride (PVDF) films prepared by horizontal Langmuir-Schaefer (LS) technique. We have prepared pure ß-phase by just increasing the number of LS layers without using additional non-ferroelectric assisting agents. Edge-on oriented CH2-CF2 units of PVDF at the air-water interface enable self-orientation of ferroelectric dipoles by means of the hydrogen bonding network. Such restricted conformation of PVDF at the air-water interface results in an increased net dipole moment with the number of LS layers. The film's ferroelectric switching and piezoelectric sensitivity are demonstrated by hysteretic polarization switching loops and butterfly-loops, respectively. Successful circular domain writing on ultrathin LS film, down to 5 monolayers of PVDF, is demonstrated. The achievement of pure ß-phase of PVDF at room temperature without using any assisting agents may be promising for non-volatile memory and piezoelectric-based, ultrathin smart sensor devices.