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Projeto de investigação
Grafeno em papel para dispositivos flexíveis: sensores e OLEDs
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Flexible OLEDs with graphene electrodes on renewable cellulose platforms
Publication . Kulyk, Bohdan; Germino, José C.; Gaspar, Diana; Fernandes, António J. S.; Deuermeier, Jonas; Carvalho, Alexandre F.; Cunha, António F. da; Pereira, Luís M. N.; Pereira, Luiz; Costa, Florinda M.; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; RSC - Royal Society of Chemistry
Graphene shows great potential as a transparent conducting material (TCM) for organic light emitting diodes (OLEDs), particularly in what concerns flexible devices. In this context, a lot of attention has been dedicated to the optimization of the graphene electrodes, to improve their electrical conductivity while maintaining high optical transparency. Moreover, for the development of flexible and sustainable devices, the choice of an appropriate substrate is a critical task. Here, we describe, for the first time, the development of OLEDs employing chemical vapour deposition (CVD) graphene anodes on cellulose nanocrystal (CNC) membranes and cellulose rolling papers. These transparent biodegradable materials provide a more environmentally conscious alternative to the conventional synthetic polymers commonly used as flexible OLED substrates. By stacking multiple graphene layers on these cellulose-based substrates, followed by the evaporation of MoO3, we improve the electrical conductivity of graphene, allowing us to fabricate third generation solution processed OLEDs, with external quantum efficiencies (EQE) of up to 0.34% and maximum brightness reaching ∼400 cd m−2. This proof-of-concept demonstration paves the way for novel environmentally friendly flexible OLEDs, realizing the synergic potential of both graphene and cellulose-based materials.
Laser-induced graphene from paper for non-enzymatic uric acid electrochemical sensing in urine
Publication . Kulyk, Bohdan; Pereira, Sónia O.; Fernandes, António J. S.; Fortunato, Elvira; Costa, Florinda M.; Santos, Nuno F.; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; Elsevier
Laser-induced graphene from paper (paper-LIG) was applied in non-enzymatic electrochemical sensing of uric acid (UA) in human urine. Paper-LIG was formed by CO2 laser modification of paper into a 3D graphene arrangement. Kinetic analysis of paper-LIG electrodes returned effective heterogeneous electron transfer standard rate constants of 1.4 × 10−3 cm s−1 and 7.8 × 10−4 cm s−1 for [Ru(NH3)6]2+/3+ and [Fe(CN)6]4−/3− redox probes, respectively. These electrodes were able to detect and quantify uric acid in PBS within the 10–300 μM range at pH between 5.6 and 7.4. At pH 7.4, a linear response (R2 = 0.999) from 10 to 250 μM was achieved, with a limit of detection of 3.97 μM and a sensitivity of 0.363 μA cm−2 μM−1. Paper-LIG electrodes denoted adequate selectivity in synthetic urine as well as in ascorbic acid (AA) and dopamine (DA)-containing electrolytes. Determination of urinary UA content in human samples returned a concentration of c.a. 1.8–1.9 mM, within the range for healthy individuals. Recoveries of samples spiked with 50 and 100 μM UA were 100.6% and 95.4%, respectively, with satisfactory reproducibility and stability. These cheap, lightweight, flexible, and eco-friendly paper-LIG biosensors for non-enzymatic quantification of UA in human urine pave the way to widespread application in the detection of other important biomarkers.
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Fundação para a Ciência e a Tecnologia
Programa de financiamento
OE
Número da atribuição
SFRH/BD/141525/2018