Charge Transport through Functionalized Graphene Quantum Dots Embedded in a Polyaniline Matrix

Abstract

Nitrogen-functionalized graphene quantum dots embedded in a polyaniline matrix (NGQD–PANI) are extremely promising candidates for the development of next-generation sensors and for thermoelectric materials design with the distinct advantage of tunability of electronic properties by controlled doping and/or by controlling the inherent disorder in the microstructure. While their application is increasing in photovoltaics, energy storage, and sensing technologies, a clear understanding of conduction in these hybrid systems is lacking. Here, we report a comprehensive study of NGQD–PANI composites with varying NGQD doping levels over a wide range of temperature. We show distinct regimes of conduction as a function of temperature, which include: a transition from Efros–Shklovskii and Larkin–Khmelnitskii variable range hopping at low temperatures to thermally driven electron transport at higher temperatures. Importantly, we find a remarkable 50-fold enhancement in conductivity for 10% NGQD-doped samples and tunability of the crossover temperature between different regimes as a function of the applied voltage bias and doping. Our work provides a general framework to understand the interplay of extrinsic parameters like temperature and voltage bias with intrinsic material properties like doping, which drives the electronic properties in these hybrid systems of technological importance.

Earth-abundant and environmentally benign Ni–Zn iron oxide intercalated in a polyaniline based nanohybrid as an ultrafast photodetector

“…Variables such as the size and shape of the NZF nanostructures, the degree of dispersion, and the kinds of interaction and interface between the organic and inorganic phases, among others, have a direct influence on properties such as conductivity, piezoresistivity, and photocurrent. 31 Previously reported results of graphene quantum dots in a polyaniline matrix, 23 ZnO nanorods assisted with polyaniline, 26 2D self-healable polyaniline-polypyrrole nanoflakes, 27 and in-situ conformal coatings of polyaniline on GaN microwires 28 showed that different experimental routes can be successful in producing organic-inorganic hybrids of polyaniline. Iron, with its low elemental cost, high earth-abundance, and environmentally benign character, has broadened the scope for material development and is a suitable material for constructing next-generation technology.…”

“…); therefore, they are applied in a wide variety of technological devices such as memory, display and telecommunication devices. [19][20][21][22][23] Currently, organic conductive polymers such as polyaniline, 19,20,24 polypyrrole, 21,22 polyacetylene, 23,25 polythiophene, and poly(3,4-ethylene dioxythiophene) 26,27 are preferred for fabricating flexible devices and have been gaining huge attention due to their unique properties, such as lowcost, easy processing and eco-friendliness. 22,23 An important class of hybrid materials is those in which the organic fractions are composed of conducting polymers such as polyaniline and polypyrrole.…”

“…[19][20][21][22][23] Currently, organic conductive polymers such as polyaniline, 19,20,24 polypyrrole, 21,22 polyacetylene, 23,25 polythiophene, and poly(3,4-ethylene dioxythiophene) 26,27 are preferred for fabricating flexible devices and have been gaining huge attention due to their unique properties, such as lowcost, easy processing and eco-friendliness. 22,23 An important class of hybrid materials is those in which the organic fractions are composed of conducting polymers such as polyaniline and polypyrrole. 22,23,[25][26][27][28][29][30] Because of its potential uses in photovoltaics, memory devices, gas sensors, and as a crucial component of plastic electronics, polyaniline (PANI) has attracted a lot of interest as a futuristic material.…”

“…22,23 An important class of hybrid materials is those in which the organic fractions are composed of conducting polymers such as polyaniline and polypyrrole. 22,23,[25][26][27][28][29][30] Because of its potential uses in photovoltaics, memory devices, gas sensors, and as a crucial component of plastic electronics, polyaniline (PANI) has attracted a lot of interest as a futuristic material. 28,29 Polyaniline exhibits many alluring properties, such as a wide bandgap (2.5 eV), short response time and excellent merits under room-temperature operation.…”

“…[32][33][34] Iron oxide and its composites combined with the conducting polymer polyaniline can be used in many different applications, such as electromagnetic shielding, 35 supercapacitors, 36 energy storage 36 and optoelectronics. 22,23,[26][27][28][29] In photodetectors, a change in electrical resistance occurs under exposure to light. For example, the combination of the n-type semiconducting NZF material with the p-type polyaniline has been reported to improve the hybrid photocurrent due to the occurrence of exciton dissociation at the interface.…”