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Projeto de investigação
1D Nanofibre Electro-Optic Networks
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Piezoelectricity Enhancement of Nanogenerators Based on PDMS and ZnSnO3 Nanowires through Microstructuration
Publication . Rovisco, Ana; Dos Santos, Andreia; Cramer, Tobias; Martins, Jorge; Branquinho, Rita; Águas, Hugo; Fraboni, Beatrice; Fortunato, Elvira; Martins, Rodrigo; Igreja, Rui; Barquinha, Pedro; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; DCM - Departamento de Ciência dos Materiais; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); ACS - American Chemical Society
The current trend for smart, self-sustainable, and multifunctional technology demands for the development of energy harvesters based on widely available and environmentally friendly materials. In this context, ZnSnO3 nanostructures show promising potential because of their high polarization, which can be explored in piezoelectric devices. Nevertheless, a pure phase of ZnSnO3 is hard to achieve because of its metastability, and obtaining it in the form of nanowires is even more challenging. Although some groups have already reported the mixing of ZnSnO3 nanostructures with polydimethylsiloxane (PDMS) to produce a nanogenerator, the resultant polymeric film is usually flat and does not take advantage of an enhanced piezoelectric contribution achieved through its microstructuration. Herein, a microstructured composite of nanowires synthesized by a seed-layer free hydrothermal route mixed with PDMS (ZnSnO3@PDMS) is proposed to produce nanogenerators. PFM measurements show a clear enhancement of d33 for single ZnSnO3 versus ZnO nanowires (23 ± 4 pm/V vs 9 ± 2 pm/V). The microstructuration introduced herein results in an enhancement of the piezoelectric effect of the ZnSnO3 nanowires, enabling nanogenerators with an output voltage, current, and instantaneous power density of 120 V, 13 μA, and 230 μW·cm-2, respectively. Even using an active area smaller than 1 cm2, the performance of this nanogenerator enables lighting up multiple LEDs and other small electronic devices, thus proving great potential for wearables and portable electronics.
Low-temperature amorphous oxide semiconductors for thin-film transistors and memristors: physical insights and applications
Publication . Martins, Jorge de Souto; Barquinha, Pedro; Kiazadeh, Asal; Goes, João
While amorphous oxides semiconductors (AOS), namely InGaZnO (IGZO), have found market application in the display industry, their disruptive properties permit to envisage for more advanced concepts such as System-on-Panel (SoP) in which AOS devices could be used for addressing (and readout) of sensors and displays, for communication, and even for memory as oxide memristors are candidates for the next-generation memories. This work concerns the application of AOS for these applications considering the low thermal budgets (< 180 °C) required for flexible, low cost and alternative substrates. For maintaining low driving voltages, a sputtered multicomponent/multi-layered high-κ dielectric (Ta2O5+SiO2) was developed for low temperature IGZO TFTs which permitted high performance without sacrificing reliability and stability. Devices’ performance under temperature was investigated and the bias and temperature dependent mobility was modelled and included in TCAD simulation. Even for IGZO compositions yielding very high thermal activation, circuit topologies for counteracting both this and the bias stress effect were suggested. Channel length scaling of the devices was investigated, showing that operation for radio frequency identification (RFID) can be achieved without significant performance deterioration from short channel effects, which are attenuated by the high-κ dielectric, as is shown in TCAD simulation. The applicability of these devices in SoP is then exemplified by suggesting a large area flexible radiation sensing system with on-chip clock-generation, sensor matrix addressing and signal read-out, performed by the IGZO TFTs. Application for paper electronics was also shown, in which TCAD simulation was used to investigate on the unconventional floating gate structure. AOS memristors are also presented, with two distinct operation modes that could be envisaged for data storage or for synaptic applications. Employing typical TFT methodologies and materials, these are ease to integrate in oxide SoP architectures.
Biowaste-derived carbon black applied to polyaniline-based high-performance supercapacitor microelectrodes: Sustainable materials for renewable energy applications
Publication . Goswami, Sumita; Dillip, Gowra Raghupathy; Nandy, Suman; Banerjee, Arghya Narayan; Pimentel, Ana; Joo, Sang Woo; Martins, Rodrigo; Fortunato, Elvira; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; DCM - Departamento de Ciência dos Materiais; International Society of Electrochemistry (ISE) | Elsevier
Biowaste, derived from cooking-oven-produced carbon nanoparticles (WCP), are incorporated into polyaniline (PANI) via in-situ chemical oxidative polymerization to achieve excellent electrochemical properties for application in supercapacitors. The WCP-PANI composite electrodes have shown high-performance charge storage, due to combinatorial effect of electrical double layer capacitance from WCP and pseudocapacitance from PANI. With increase in the WCP percolation, work function of PANI is increased, which improves the charge-trapping capabilities of composites. For such distinct charge-trapping mechanism, areal capacitance of the composite microelectrode remains near-constant with increase in scan rate or current density. This indicates the suppression of diffusion limitations at higher scan rates to considerably enhance the rate capability. Also, with increasing polymerization time, strong interaction in this conjugated system greatly improves the charge-transfer reaction between PANI and WCP. The areal capacitance of the composite electrode is found to increase more than 600 times over pure PANI electrode. Moreover, energy-power performance of the microelectrode reveals almost 550% increment in the power density with a mere 1% decrement in energy density. Such rationally synthesized WCP-PANI composite electrodes using biowaste carbon nanomaterials, provide opportunities for the development of next-generation green-supercapacitors with improved energy storage performance.
Green Nanotechnology from Waste Carbon-Polyaniline Composite
Publication . Goswami, Sumita; Nandy, Suman; Deuermeier, Jonas; Marques, Ana Carolina; Nunes, Daniela; Patole, Shashikant P.; Costa, Pedro M. F. J.; Martins, Rodrigo; Fortunato, Elvira; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; DCM - Departamento de Ciência dos Materiais; John Wiley and Sons Inc.
This study reports on the qualitative analysis of photoluminescence effect generated from waste carbon of cooking oven by facile cost-effective material engineering. The waste carbon product as a form of carbon nanoparticles (CNPs) is incorporated within a conjugate polymer, namely, polyaniline (PANI) to produce CNP-PANI composites that have shown excitation-wavelength-independent triple-band photoluminescence emission effect and highly sensitive Fe+3 ion detection ability. Herein the waste carbon material, while functionalized within the conjugated polymer, needs no further acid treatment or surface modification thus making the process cheaper, environmentally benign, and useful for green nanotechnology. The excitation-wavelength-independent unique triple-band photoluminescence spectrum is the direct consequence of carbon-polyaniline synergy in pi-pi transition and the surface passivation of CNPs by the -NH2 group rich aniline during in-situ polymerization. The current scenario has been studied for the samples prepared with different CNP concentrations for different reaction times and discussed in details with supportive physico-chemical characterizations. Moreover, the present study has demonstrated that the current material can be used as a fluorescent sensing platform for Fe+3 ions with high sensitivity and selectivity criteria where the detection limit of the sensing probe has a value as low as 12 x 10(-9) nM.
Planar Dual-Gate Paper/Oxide Field Effect Transistors as Universal Logic Gates
Publication . Gaspar, Diana; Martins, Jorge; Bahubalindruni, Pydi; Pereira, Luís; Fortunato, Elvira; Martins, Rodrigo; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; Wiley
Electronics on paper enable some specific applications out of conventional ones which require innovative approaches and concepts on the design of devices and systems. Within this context, this work demonstrates that a unique set of characteristics can be combined in planar dual-gate oxide–based field effect transistors with a back floating electrode using paper simultaneously as substrate and dielectric. The working principle of these transistors relies on the formation of electric double layers at the semiconductor/paper and paper/back floating electrode interfaces (associated to ions displacement within the paper) that can be disturbed by a voltage applied at a secondary gate, by the back floating potential or by the combination of both. This feature allows for the control of the on-voltage of the transistors, from depletion to enhancement mode, for instance. Moreover, this specific characteristic allows the implementation of universal logic gates (NAND and NOR) using only one transistor, by setting the proper combination of the voltage level applied at each gate. This way a simple and universal device architecture can be envisaged towards the simplification of the production of low power electronic systems on paper.
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Entidade financiadora
European Commission
Programa de financiamento
H2020
Número da atribuição
685758