With stringent laws on emissions being effected every day globally, scientists have taken up the challenge to develop alternative eco-friendly and sustainable energy sources in a bid to curb the ever rising energy demand. Energy harvesting is amongst the most suitable exploitable technological alternative. Piezoelectric materials have been the highest explored energy transducers with zinc oxide emerging as the most popular despite the inherent drawbacks it possesses. Recent technological advances have led to the establishment of Poly (vinylidene ﬂuoride) (PVDF) which has excellent piezoelectric attributes. Nonetheless, successful development of PVDF-based piezoelectric devices depends on the effective fabrication of polar crystalline structures, such as the β phase structure. Carbon quantum dots (CQDs) have been put forward as potential substitute of the metal based quantum dots utilized to induce the β form in PVDF matrix, however, to date no one has attempted to fabricate such composite systems.
Recently, Southwest Jiaotong University: Songyuan Ma , Long Jin, Xi Huang , Professor Jun Lu and Professor Weiqing Yang in collaboration with Professor Rui Huang at Sichuan University and Dr. Christos Riziotis at National Hellenic Research Foundation in Greece designed and fabricated a novel PVDF/CQDs-based piezoelectric photo-luminescent composite system. They successfully prepared PVDF/CQDs composites by solution casting followed by a high-pressure crystallization process. Their work is currently published in the research journal, Advanced Material Interfaces.
The research technique employed commenced with the morphological and dispersion analysis of the CQDs in PVDF matrix. Next, the researchers engaged in high-pressure experiments for the PVDF/CQDs composite where they used a prototype self-made piston-cylinder apparatus. They then performed transmission electron microscopy observations followed closely by laser scanning confocal microscope detections. Lastly, an energy harvesting performance of the samples, without any electrical poling treatment, was undertaken.
The authors observed that the introduction of 3D quasi-spherical CQDs induced the self-assembly of polymorphic substructures in the PVDF crystallites at high pressure, and piezoelectric 3D nanosheet arrays, 1D nanometer small sticks, and 1D nanowires, respectively, were formed in situ as the concentration of CQDs increased. Additionally, they recorded that in the absence of electrical polarization treatment, the maximum open-circuit voltage output density of the durable composite system reached 19.2 V cm−2 and short-circuit current output density of 550 nA cm−2, both far exceeding that of pure PVDF.
Their study presented the successful design and fabrication of the novel PVDF/CQDs-based poling-free self-powered hybrid composite. They mainly observed that the in situ formed nanostructures with unique morphologies considerably enhanced the adeptness of mechanical-to-electrical conversion. Altogether, the work indeed is a step in the right direction towards the development of environmental friendly self-powered devices, and the material system fabricated here possess boundless potential in the field of cell imaging, autonomous monitoring devices and biosensors.
Songyuan Ma, Long Jin, Xi Huang, Christos Riziotis, Rui Huang, Chaoliang Zhang, Jun Lu and Weiqing Yang. Nanogenerators Begin to Light Up: A Novel Poling-Free Piezoelectric System with Multicolor Photoluminescence as an Efficient Mechatronics Development Platform. Advanced Material Interfaces 2018, 1800587Go To Advanced Material Interfaces