View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Archive Ouverte en Sciences de l'Information et de la Communication Energy Harvesting using a Lead Zirconate Titanate (PZT) Thin Film on a Polymer Substrate Thibault Dufay, Benoit Guiffard, Raynald Seveno, Jean-Christophe Thomas To cite this version: Thibault Dufay, Benoit Guiffard, Raynald Seveno, Jean-Christophe Thomas. Energy Harvesting using a Lead Zirconate Titanate (PZT) Thin Film on a Polymer Substrate. Energy Technology, Wiley, 2018, 6 (5), pp.917-921. 10.1002/ente.201700732. hal-01757007 HAL Id: hal-01757007 https://hal.archives-ouvertes.fr/hal-01757007 Submitted on 24 Oct 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Energy Harvesting using aLead Zirconate Titanate (PZT) Thin Film on aPolymer Substrate Thibault Dufay,*[a] BenoitGuiffard,[a] RaynaldSeveno,[a] and Jean-Christophe Thomas[b] Acomposite structure with an highly flexible polymersub- performed to confirm the ferroelectric characteristics of the strate and athin film of lead zirconate titanate, Pb(Zr,Ti)O3 composite.Finally,energy harvestingmeasurements are real- (PZT),isrealized using an all-chemical process.The fabrica- ized with interdigitated electrodes structure.Amaximal tion of the structure comprises three steps:first, PZT is de- energy density of 20 mJcmÀ2 is obtainedwith manual me- posited on an aluminum thin foil, then the PZT thin film is chanical excitation and an output voltage up to 35 Vunder bondedtoa polymer, and, finally,aluminum foil is removed free oscillations conditions in bendingmode.This demon- by selectivechemical etching. Structural characterization strates that the recently developed PZT/polymer thin films techniques are used to ensurethe quality of the PZT/poly- are very promising for low-frequency vibrating energy-har- mer composite structure.Electrical measurements are also vestingapplications. Introduction Nowadays,energy harvesting from ambientand renewable the piezoelectric material from aprimary substratetothe sources is an objective so that we can become independent polymer substrate. from fossils energies.This objective is now close to be Our research team has recently developed reliable tech- reached because many research teams are working toward niquesfor the fabrication of thin films of lead zirconatetita- this goal. Forexample,when the wind is taken as an energy nate (PZT) on aflexible metallic substrate,acommercial source,there are already various scales of power that could aluminum(Al) foil with thickness less than 30 mm.[2] Thefab- be generated. Giant offshore windmills that are being devel- rication process is based on chemical solution deposition oped will soon provideenough energytopower cities.Ona (CSD) method and is cost effective.The light weight and the smaller scale,apersonal windmill could be used to power a weak stiffness of the micro-generator make it sensitive to air single house.Inaddition, the designofthe windmill could be flow.This PZT/Alstructure has been thoroughly character- modified in order to integrate it into the city landscape.[1] ized[3–5] and shows promising results for energyharvesting However, when the power needed is very small, for example under mechanical stress.[6] However, the metal-insulator- for powering small sensorsrequiring few hundreds of mW in metal (MIM) structure with full electrodes that has been operation, it would not be interesting to usethose kinds of tested implies ahuge capacitance,which limits the obtained wind energy harvesters whichwould waste part of the har- electrical energy density.Amore efficient design for energy vested energy.That is why some researchers are working on harvestingisthe interdigitated electrodes (IDE) structure low power energyharvesters that are capable of harvesting (without ground plane), whichalso presents the advantage of energy from low speed wind. working in the 33 (longitudinal) piezoelectric mode whose Piezoelectric vibrating energy harvesters are apart of the piezoelectric coefficient d33 is roughly twice as large as the family of the mechanical energyharvesters and they could d31 in transversemode. be efficientenough to scavenge energy from low speed wind such as abreeze.Realizationofthis type of generators, which are able to withstandlarge wind flow induced deflec- [a] T. Dufay,Prof. B. Guiffard, R. Seveno tions,requires the developmentofanactive thin-layer on IETR UMR CNRS 6164, FacultØ des Sciences et Techniques flexible and insulating substrates.The useofpiezoelectric UniversitØ Bretagne Loire, UniversitØ de Nantes 2rue de la Houssinire,BP92208,44322 Nantes Cedex 3(France) polymers was not possible due to their low piezoelectric E-mail: [email protected] properties and the weakelectro-mechanical coupling. Thus, [b] J.-C. Thomas the challenge is to obtain apiezoelectric ceramic material, GeM (Institute for Research in Civil and mechanical Engineering), UMR which requires high crystallization temperatures (>6008C), CNRS 6183 on apolymer substrate that cannot withstand such high tem- UniversitØ de Nantes-Ecole Centrale Nantes 2rue de la Houssinire,BP92208, 44322, Nantes Cedex 3(France) peratures.Inthis case,two main methods may be envisaged: to develop acomplete low temperature process or to transfer 1 To obtain an IDE structure,PZT films must be deposited realizedtostudy the energy harvesting properties of the on an insulating substratewith good flexibility.Specific poly- transferred PZT thin film. mer materials including some thermoplastics are good candi- Structural characterizations are given in Figure 2: panel dates because they present the required properties.However, (a) X-raydiffraction (XRD) patterns of PZT on aluminum the direct synthesis of PZT ontothe polymeric substrate is and transferred to PET,and panel (b) cross-section SEM avoided by the low melting temperature of the soft polymers. image of PZT transferred on PET.XRD patterns of PZT/Al One solution is to transfer the PZT thin film, obtained by and PZT/PET are roughly the same except for the substrates classicalmethods on rigid substrates,onto the polymeric sub- peaks.All the peaks of PZT remain at their positionsbut the strate.This solution was used to realizePZT on apolymer, peak of aluminum disappearsinthe pattern of PZT/PET and but the method employed—laserlift-off—is expensiveand is replaced by the peak of the polymer substrate.The slight could be difficult to transfer to the industry.[7–9] This process difference in 2V angle observed is aconsequence of the flexi- is based on chemical solution depositionofPZT on high-cost ble substrates used. They induce different base surfaces for rigid and transparentsubstrate (e.g.,sapphire). After this, the two cases,leadingtoshifts in the 2V angle. the polymer substrate is attached to PZT.The flexible piezo- Thecross-sectionSEM image of transferred PZT (Fig- electric structure is released from the rigid substrate by mul- ure 2b)has been realized to estimate the bondstrengthbe- tiple laser shots (squared spots of 500 mm500 mm) to cover tween PZT and PU and between the two layers of polymer. all the centimetric surface of the sample. Thesteps require SEM observations reveal good adhesion between the oxide high cost equipmentand are not easily adaptablefor serial layer and the stack of polymers. production. This is why the current study is devoted to the Thetransferred structure (PZT/PET) must be poled development of asimplemethod to achieve aPZT/polymer before any electric tests. In order to induce macroscopic pie- structure. zoelectric properties to the transferred PZT,astatic electric Here,wefocus on the processdeveloped to transfer apie- field is applied through the interdigitated electrodes.Apho- zoelectric PZT thin film from aluminumfoil to aflexible polymersubstrate.Photographs of PZT/Aland PZT/polymer bilayers are presented in Figure 1. Polyethyleneterephtalate (PET) is the most used polymerasinsulating and flexible substrate. Thechemical process is cheap and simple,and would be easily transferred to an industrial scale.Inaddition, with this method, the metallic substrateisremoved from the complete surface (~6 cm2)ofPZT thin film in one step whereas the laser lift-off methodimplies severallaser shots to separate PZT from the first substrate.Structural and elec- trical characterizations of the PZT/polymer thin film are also presented to confirm the good quality of the transferred PZT thin film. Finally,energy harvestingmeasurements with IDE structures after the transfer to the polymer substrateare re- alized to explore the possibilities of this new generator. Figure 1. Photographs of a) PZT/Al structure and b) PZT/PET IDE structure. Results and Discussion Themethod described in Experimental Section demonstrates how to transfer aPZT thin layer ontoaflexible substrate. Theinteresting pointisthat it is possible using asimple Figure 2. a) XRD patternsofPZT before and after transfer from the aluminum chemical method. Theobtained piezoelectric thin film on a substrate to the PET substrate. b) Cross-sectionSEM imagesofPZT