Buckminsterfullerene hybridized zinc oxide tetrapods: defects and charge transfer induced optical and electrical response

Abstract

Buckminster fullerene (C60) based hybrid metal oxide materials are receiving considerable attention because of their excellent fundamental and applied aspects, like semiconducting, electron transfer, luminescent behaviors, etc. and this work briefly discusses the successful fabrication of C60 decorated ZnO tetrapod materials and their detailed structure-property relationships including device sensing applications. The electron microscopy investigations indicate that a quite dense surface coverage of ZnO tetrapods with C60 clusters is achieved. The spectroscopy studies confirmed the identification of the C60 vibrational modes and the C60 induced changes in the absorption and luminescence properties of the ZnO tetrapods. An increased C60 concentration on ZnO results in steeper ZnO bandgap absorption followed by well-defined free exciton and 3.31 eV line emissions. As expected, higher amounts of C60 increase the intensity of C60-related visible absorption bands. Pumping the samples with photons with an energy corresponding to these absorption band maxima leads to additional emission from ZnO showing an effective charge transfer phenomenon from C60 to the ZnO host. The density of states model obtained from DFT studies for pure and C60 coated ZnO surfaces confirms the experimental observations. The fabricated C60-ZnO hybrid tetrapod based micro- and nanodevices showed interesting ethanol gas sensing characteristics.

Probing surface states in C60decorated ZnO microwires: detailed photoluminescence and cathodoluminescence investigations

“…[1][2][3][4][5] Besides the importance of the single wide bandgap oxide semiconductor, ZnO-based composites have gained increasing attention among the international community due to the possibility to extend their scientic and technological uses by enhancing the properties of the combined compounds. Particularly, ZnO-based composites have already demonstrated their advanced multifunctional properties for photocatalytic, chemical and bio-sensing purposes, [6][7][8][9][10][11] to mention just a few elds.…”

“…[30][31][32][33] When compared with the single phase material, ZnO-based composites are expected to lead to changes in the luminescence response either by the presence of additional material's phases or through processes implying cooperative phenomena between the involved materials, such as energy or charge transfer. [6][7][8][34][35][36] Therefore, the knowledge of the composites' optical properties is a key parameter to boost the development of materials with enhanced and multifunctional properties.…”

“…Even though there are already some previous studies concerning ZnO/C 60 composites, 8,[37][38][39][40][41][42][43] most of them concentrate on the general characterisation of the materials' properties (mostly structural and morphological) and their possible applications, namely in the eld of photocatalysis 40,43 or in photovoltaic devices. 37,42 Nevertheless, beyond the relevance of applications, a complete knowledge of the fundamental properties of these new materials is also of crucial importance to the understanding of the materials' potentialities for further device development and even to be able to control/tune the desired features.…”

“…ZnO MW were synthesised by the ame transport technique 44,45 and further coated with C 60 molecules by the drop-casting method. 8,46 The optical response of the resulting ZnO/C 60 composites is compared with that of the ZnO MW reference sample, enabling to conclude that the effect of increasing C 60 ooding allows changing the light outcome, which may enhance the application of such composites for sensing purposes.…”

Assessment of synthesis approaches for tuning the photocatalytic property of ZnO nanoparticles

“…These ROS then proceeds the reaction further and leads to the breakdown of complex organic molecules, such as dyes [15]. The various defect states present in ZnO NPs [16], such as zinc and oxygen vacancies, may trap either electrons or holes leading to their reduced recombination and thereby, generating higher number of ROS [17].…”