The purpose of this work was to investigate ways to modify Silex sol-gel deposition of PZT (PbZrxTi(1-x)O3, Lead Zirconate Titanate) in order to improve its properties for energy harvesting applications. A number of methods to improve the figure of merit for energy harvesting (FOM= e312/ε), cause self-polarization, increase lifetime, reduce cost, increase throughput or simplify processing were tested. In order to create a barrier preventing lead diffusion into the substrate, a method to oxidize the bottom electrode’s Ti adhesion layer into TiO2 by RTA (Rapid Thermal Anneal) was tested. Oxidation was successfully achieved and was found to aid in self-polarization, thereby increasing the FOM for films without post-processing polarization. An extended lifetime is expected, but has not yet been confirmed by testing. A seed layer of a different material was tested and compared to a PZT-based seed layer. The new seed layer was found to give highly (100) crystalline PZT with improved self-polarized e31,f and FOM. The new seed layer was also found to be less sensitive to processing variations. Oxygen control during crystallization of the PZT was used in an attempt to generate PZT layers with oxygen vacancies. These hypoxic layers were intended to polarize the film, but were found to reduce the FOM and lead to partial delamination of the film due to stress. A different type of PZT sol-gel was tested as an alternative to the PZT sol-gel in use at Silex. The tested solution was found to result in PZT films with similar properties to those generated by the original type, but the tested type allowed for single layer thicknesses nearly three times thicker than the original type, thereby increasing the throughput and reducing manufacturing costs. / Arbetet undersöker metoder att modifiera Silex sol-gel deponeringsprocess för PZT (PbZrxTi(1-x)O3, blyzirconiumtitanat) i syfte att att förbättra dess egenskaper för energy harvesting. Ett antal metoder testades för att förbättra godhetstalet för energy harvesting ("figure of merit", FOM= e312/ε), åstadkomma självpolarisering, utöka livslängden, minska kostnader, öka produktionskapaciteten eller förenkla tillverkningsprocessen. En metod testades för att oxidera bottenelektrodens fästlager av Ti till TiO2 genom RTA (Rapid Thermal Anneal). Detta för att åstadkomma en barriär som förhindrar diffusion av bly in i substratet. Oxidering uppnåddes och mätningar visade en positiv inverkan på självpolariseringen, vilket ökade godhetstalet för energy harvesting i PZT-skikt utan efterbehandlingspolarisering. En utökad livslängd förväntas, men har ännu inte bekräftats via testning. Ett seedlager av ett annat material testades och jämfördes med ett PZT-baserat seedlager. Det nya seedlagret gav välkristalliserat (100) PZT med förbättrade värden för e31,f och godhetstal för energy harvesting. Det nya seedlagret var även mindre känsligt för processvariationer. Tester med begränsad syretillgång under kristallisering av PZT genomfördes för att generera PZT-lager med syrevakanser. Syftet med dessa hypoxiska PZT-lager var att polarisera materialet, men testerna resulterade i försämrat godhetstal för energy harvesting, samt partiell delaminering av PZT-skiktet orsakad av spänningar i materialet. Som alternativ till den PZT sol-gel som användes på Silex testades en annan typ av PZT sol-gel. Den testade sol-gelen resulterade i PZT-skikt med liknande materialegenskaper som hos den ursprungliga typen, men med möjlighet till nästan tre gånger så tjocka enskilda lager, vilket leder till ökad produktionskapacitet och minskade produktionskostnader.

Polymer-based piezoelectric and triboelectric generators form the basis of well-known energy harvesting methods that are capable of transforming ambient vibrational energy into electrical energy via electrical polarization changes in a material and contact electrification, respectively. However, the low energy conversion efficiency and limited thermal stability of polymeric materials hinder practical application. While nanostructured polymers and polymer-based nanocomposites have been widely studied to overcome these limitations, the performance improvement has not been satisfactory due to limitations pertaining to long-standing problems associated with polymeric materials; such as low crystallinity of nanostructured polymers, and in the case of nanocomposites, poor dispersion and distribution of nanoparticles in the polymer matrix. In this thesis, novel functional polymeric nanomaterials, for stable and physically robust energy harvesting applications, are proposed by developing advanced nanofabrication methods. The focus is on ferroelectric polymeric nanomaterials, as this class of materials is particularly well-suited for both piezoelectric and triboelectric energy harvesting. The thesis is broadly divided into two parts. The first part focuses on Nylon-11 nanowires grown by a template-wetting method. Nylon-11 was chosen due to its reasonably good ferroelectric properties and high thermal stability, relative to more commonly studied ferroelectric polymers such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)). However, limitations in thin-film fabrication of Nylon-11 have led to poor control over crystallinity, and thus investigation of this material for practical applications had been mostly discontinued, and its energy harvesting potential never fully realised. The work in this thesis shows that these problems can be overcome by adopting nanoporous template-wetting as a versatile tool to grow Nylon-11 nanowires with controlled crystallinity. Since the template-grown Nylon-11 nanowires exhibit a polarisation without any additional electrical poling process by exploiting the nanoconfinement effect, they have been directly incorporated into nano-piezoelectric generators, exhibiting high temperature stability and excellent fatigue performance. To further enhance the energy harvesting capability of Nylon-11 nanowires, a gas -flow assisted nano-template (GANT) infiltration method has been developed, whereby rapid crystallisation induced by gas-flow leads to the formation of the ferroelectric δʹ-phase. The well-defined crystallisation conditions resulting from the GANT method not only lead to self-polarization but also increases average crystallinity from 29 % to 38 %. δʹ-phase Nylon-11 nanowires introduced into a prototype triboelectric generator are shown to give rise to a six-fold increase in output power density as observed relative to the δʹ-phase film-based device. Interestingly, based on the accumulated understanding of the template-wetting method, Nylon-11, and energy harvesting devices, it was found that thermodynamically stable α-phase Nylon-11 nanowires are most suitable for triboelectric energy generators, but not piezoelectric generators. Notably, definitive dipole alignment of α-phase nanowires is shown to have been achieved for the first time via a novel thermally assisted nano-template infiltration (TANI) method, resulting in exceptionally strong and thermally stable spontaneous polarization, as confirmed by molecular structure simulations. The output power density of a triboelectric generator based on α-phase nanowires is shown to be enhanced by 328 % compared to a δʹ-phase nanowire-based device under the same mechanical excitation. The second part of the thesis presents recent progress on polymer-based multi-layered nanocomposites for energy harvesting applications. To solve the existing issues related to poor dispersion and distribution of nanoparticles in the polymer matrix, a dual aerosol-jet printing method has been developed and applied. As a result, outstanding dispersion and distribution. Furthermore, this method allows precise control of the various physical properties of interest, including the dielectric permittivity. The resulting nanocomposite contributes to an overall enhancement of the device capacitance, which also leads to high-performance triboelectric generators. This thesis therefore presents advances in novel functional polymeric nanomaterials for energy harvesting applications, with improved performance and thermal stability. It further offers insight regarding the long-standing issues in the field of Nylon-11, template-wetting, and polymer-based nanocomposites.