[1] Zare V. A comparative exergoeconomic analysis of different ORC configurations for binary geothermal power plants. Energy Convers Manage. 2015;105:127.

[2] Musa M, Hill C, Sotiropoulos F, Guala M. Performance and resilience of hydrokinetic turbine arrays under large migrating fluvial bedforms. Nat Energy. 2018;3:839.

[3] Pan H, Li H, Zhang T, Laghari AA, Zhang Z, Yuan Y. A portable renewable wind energy harvesting system integrated S-rotor and H-rotor for self-powered applications in high-speed railway tunnels. Energy Convers Manage. 2019;196:56.

[4] Wang X, Song W-Z, You M-H, Zhang J, Yu M, Fan Z, Ramakrishna S, Long Y-Z. Bionic single-electrode electronic skin unit based on piezoelectric nanogenerator. ACS Nano. 2018;12:8588.

[5] Luo J, Wang Z, Xu L, Wang AC, Han K, Jiang T, Lai Q, Bai Y, Tang W, Fan FR. Flexible and durable wood-based triboelectric nanogenerators for self-powered sensing in athletic big data analytics. Nat Commun. 2019;10:5147.

[6] Gu L, Liu J, Cui N, Xu Q, Du T, Zhang L, Wang Z, Long C, Qin Y. Enhancing the current density of a piezoelectric nanogenerator using a three-dimensional intercalation electrode. Nat Commun. 2020;11:1030.

[7] Jiang T, Pang H, An J, Lu P, Feng Y, Liang X, Zhong W, Wang ZL. Robust swing-structured triboelectric nanogenerator for efficient blue energy harvesting. Adv Energy Mater. 2020;10:2000064.

[8] Harper W. Contact electrification of semiconductors. Br J Appl Phys. 1960;11:324.

[9] Lowell J. Tunnelling between metals and insulators and its role in contact electrification. J Phys D Appl Phys. 1979;12:1541.

[10] Grzybowski BA, Fialkowski M, Wiles JA. Kinetics of contact electrification between metals and polymers. J Phys Chem B. 2005;109:20511.

[11] Willatzen M, Wang ZL. Contact electrification by quantum-mechanical tunneling. Research. 2019;2019:11.

[12] Nguyen V, Zhu R, Yang R. Environmental effects on nanogenerators. Nano Energy. 2015;14:49.

[13] Gu L, Cui N, Liu J, Zheng Y, Bai S, Qin Y. Packaged triboelectric nanogenerator with high endurability for severe environments. Nanoscale. 2015;7:18049.

[14] Wang X, Niu S, Yin Y, Yi F, You Z, Wang ZL. Triboelectric nanogenerator based on fully enclosed rolling spherical structure for harvesting low-frequency water wave energy. Adv Energy Mater. 2015;5:1501467.

[15] Ahmed A, Hassan I, Helal AS, Sencadas V, Radhi A, Jeong CK, El-Kady MF. Triboelectric nanogenerator versus piezoelectric generator at low frequency (< 4 Hz): a quantitative comparison. Iscience. 2020;23: 101286.

[16] Yi Z, Liu Z, Li W, Ruan T, Chen X, Liu J, Yang B, Zhang W. Piezoelectric dynamics of arterial pulse for wearable continuous blood pressure monitoring. Adv Mater. 2022;34:2110291.

[17] Kang J, Liu T, Lu Y, Lu L, Dong K, Wang S, Li B, Yao Y, Bai Y, Fan W. Polyvinylidene fluoride piezoelectric yarn for real-time damage monitoring of advanced 3D textile composites. Compos B. 2022;245: 110229.

[18] Yu Y, Luo C, Chiba H, Shi Y, Narita F. Energy harvesting and wireless communication by carbon fiber-reinforced polymer-enhanced piezoelectric nanocomposites. Nano Energy. 2023;113: 108588.

[19] Roberts S. Dielectric and piezoelectric properties of barium titanate. Phys Rev. 1947;71:890.

[20] Egerton L, Dillon DM. Piezoelectric and dielectric properties of ceramics in the system potassium-sodium niobate. J Am Ceram Soc. 1959;42:438.

[21] Wang J, Neaton J, Zheng H, Nagarajan V, Ogale S, Liu B, Viehland D, Vaithyanathan V, Schlom D, Waghmare U. Epitaxial BiFeO3 multiferroic thin film heterostructures. Science. 2003;299:1719.

[22] Wang ZL, Song J. Piezoelectric nanogenerators based on zinc oxide nanowire arrays. Science. 2006;312:242.

[23] Liu W, Ren X. Large piezoelectric effect in Pb-free ceramics. Phys Rev Lett. 2009;103: 257602.

[24] Lee MH, Kim DJ, Park JS, Kim SW, Song TK, Kim MH, Kim WJ, Do D, Jeong IK. High-performance lead-free piezoceramics with high curie temperatures. Adv Mater. 2015;27:6976.

[25] Kawai H. The piezoelectricity of poly (vinylidene fluoride). Jpn J Appl Phys. 1969;8:975.

[26] Lovinger AJ. Ferroelectric polymers. Science. 1983;220:1115.

[27] Chu B, Zhou X, Ren K, Neese B, Lin M, Wang Q, Bauer F, Zhang Q. A dielectric polymer with high electric energy density and fast discharge speed. Science. 2006;313:334.

[28] Sousa R, Nunes-Pereira J, Ferreira J, Costa C, Machado A, Silva M, Lanceros-Mendez S. Microstructural variations of poly(vinylidene fluoride co-hexafluoropropylene) and their influence on the thermal, dielectric and piezoelectric properties. Polym Test. 2014;40:245.

[29] Martins P, Lopes A, Lanceros-Mendez S. Electroactive phases of poly(vinylidene fluoride): Determination, processing and applications. Prog Polym Sci. 2014;39:683.

[30] Lv F, Lin J, Zhou Z, Hong Z, Wu Y, Ren Z, Zhang Q, Dong S, Luo J, Shi J. In-situ electrostatic field regulating the recrystallization behavior of P (VDF-TrFE) films with high β-phase content and enhanced piezoelectric properties towards flexible wireless biosensing device applications. Nano Energy. 2022;100: 107507.

[31] Harrison J, Ounaies Z, Bushnell DM. Piezoelectric polymers. NASA Langley Research Center. 2001. https://ntrs.nasa.gov/citations/20020044745. Accessed 1 Dec 2001.

[32] An S, Jo HS, Li G, Samuel E, Yoon SS, Yarin AL. Sustainable nanotextured wave energy harvester based on ferroelectric fatigue-free and flexoelectricity-enhanced piezoelectric P(VDF-TrFE) nanofibers with BaSrTiO3 nanoparticles. Adv Funct Mater. 2020;30:2001150.

[33] Choi D, Jo H, Yoon T, Park D, Kim K, Kim YI, Song YJ, Yoon SS, An S. Transparent, flexible, and highly sensitive piezocomposite capable of harvesting and monitoring kinetic movements of microbubbles in liquid. Adv Funct Mater. 2023;33:2307607.

[34] Shim J, Son DI, Lee JS, Lee J, Lim G-H, Cho H, Kim E-Y, Bu SD, Sungbin I, Jeong CK. BNNT-ZnO QDs nanocomposites for improving piezoelectric nanogenerator and piezoelectric properties of boron nitride nanotube. Nano Energy. 2022;93:106886.

[35] Kim S-R, Yoo J-H, Kim JH, Cho YS, Park J-W. Mechanical and piezoelectric properties of surface modified (Na, K) NbO3-based nanoparticle-embedded piezoelectric polymer composite nanofibers for flexible piezoelectric nanogenerators. Nano Energy. 2021;79: 105445.

[36] Yu D, Zheng Z, Liu J, Xiao H, Huangfu G, Guo Y. Superflexible and lead-free piezoelectric nanogenerator as a highly sensitive self-powered sensor for human motion monitoring. Nano-Micro Lett. 2021;13:117.

[37] Lv F, Hong Z, Ahmad Z, Li H, Wu Y, Huang Y. Design of flexible piezoelectric nanocomposite for energy harvesters: a review. Energy Mater Adv. 2023;4:0043.

[38] Wang Z, Maruyama K, Narita F. A novel manufacturing method and structural design of functionally graded piezoelectric composites for energy-harvesting. Mater Des. 2022;214: 110371.

[39] Kim Y-G, Kim KT, Park SC, Heo DH, Hyeon DY, Mallem SPR, Park K-I. Enhanced poling efficiency via a maximized organic-inorganic interfacial effect for water droplet-driven energy harvesting. Nano Energy. 2022;98:107238.

[40] Taleb S, Badillo M, Flores-Ruiz FJ, Acuautla M. From synthesis to application: High-quality flexible piezoelectric sensors fabricated from tetragonal BaTiO3/P (VDF-TrFE) composites. Sens Actuators A. 2023;361: 114585.

[41] Yaseen HMA, Park S. P (VDF-TrFE)/BaTiO3 nanocomposite Langmuir-Schaefer thin film for piezoelectric nanogenerator. J Alloys Compd. 2023;952: 169940.

[42] Kim D, Yang Z, Cho J, Park D, Kim DH, Lee J, Ryu S, Kim SW, Kim M. High-performance piezoelectric yarns for artificial intelligence-enabled wearable sensing and classification. EcoMat. 2023;5: e12384.

[43] Su C, Zhang L, Zhang Y, Huang X, Ye Y, Xia Y, Gong Z, Qin X, Liu Y, Guo S. P (VDF-TrFE)/BaTiO3 nanofibrous membrane with enhanced piezoelectricity for high PM0. 3 Filtration and reusable face masks. ACS Appl Mater Interfaces. 2023;15:5845.

[44] An S, Kim YI, Jo HS, Kim M-W, Swihart MT, Yarin AL, Yoon SS. Oxidation-resistant metallized nanofibers as transparent conducting films and heaters. Acta Mater. 2018;143:174.

[45] Jo HS, Samuel E, Kwon H-J, Joshi B, Kim M-W, Kim T-G, Swihart MT, Yoon SS. Highly flexible transparent substrate-free photoanodes using ZnO nanowires on nickel microfibers. Chem Eng J. 2019;363:13.

[46] Salimi A, Yousefi AA. Analysis method: FTIR studies of β-phase crystal formation in stretched PVDF films. Polym Test. 2003;22:699.

[47] Chen X, Parida K, Wang J, Xiong J, Lin MF, Shao J, Lee PS. A stretchable and transparent nanocomposite nanogenerator for self-powered physiological monitoring. ACS Appl Mater Interfaces. 2017;9:42200.

[48] Arrigoni A, Brambilla L, Bertarelli C, Serra G, Tommasini M, Castiglioni C. P(VDF-TrFE) nanofibers: structure of the ferroelectric and paraelectric phases through IR and Raman spectroscopies. RSC Adv. 2020;10:37779.

[49] Bhavanasi V, Kumar V, Parida K, Wang J, Lee PS. Enhanced piezoelectric energy harvesting performance of flexible PVDF-TrFE bilayer films with graphene oxide. ACS Appl Mater Interfaces. 2016;8:521.

[50] Yuan X, Gao X, Yang J, Shen X, Li Z, You S, Wang Z, Dong S. The large piezoelectricity and high power density of a 3D-printed multilayer copolymer in a rugby ball-structured mechanical energy harvester. Energy Environ Sci. 2020;13:152.

[51] Park S-E, Shrout TR. Ultrahigh strain and piezoelectric behavior in relaxor based ferroelectric single crystals. J Appl Phys. 1804;1997:82.

[52] Ma W, Cross LE. Flexoelectric effect in ceramic lead zirconate titanate. Appl Phys Lett. 2005;86: 072905.

[53] Shen Z-Y, Li Y-M, Jiang L, Li R-R, Wang Z-M, Hong Y, Liao R-H. Phase transition and electrical properties of LiNbO3-modified K0.49Na0.51NbO3 lead-free piezoceramics. J Mater Sci Mater Electron. 2011;22:1071.

[54] Chu B, Salem D. Flexoelectricity in several thermoplastic and thermosetting polymers. Appl Phys Lett. 2012;101: 103905.

[55] Janas VF, Safari A. Overview of fine-scale piezoelectric ceramic/polymer composite processing. J Am Ceram Soc. 1995;78:2945.

[56] Nunes-Pereira J, Sencadas V, Correia V, Rocha JG, Lanceros-Mendez S. Energy harvesting performance of piezoelectric electrospun polymer fibers and polymer/ceramic composites. Sens Actuators A. 2013;196:55.

[57] Mishra S, Unnikrishnan L, Nayak SK, Mohanty S. Advances in piezoelectric polymer composites for energy harvesting applications: a systematic review. Macromol Mater Eng. 2019;304:1800463.

[58] Ma W, Cross LE. Flexoelectricity of barium titanate. Appl Phys Lett. 2006;88: 232902.

[59] Gao J, Xue D, Liu W, Zhou C, Ren X. Recent progress on BaTiO3-based piezoelectric ceramics for actuator applications. Actuators. 2017;6:24.

[60] Zhang Q, Cagin T, Goddard WA. The ferroelectric and cubic phases in BaTiO3 ferroelectrics are also antiferroelectric. Proc Natl Acad Sci U S A. 2006;103:14695.

[61] Potnis PR, Tsou N-T, Huber JE. A review of domain modelling and domain imaging techniques in ferroelectric crystals. Materials. 2011;4:417.

[62] Acosta M, Novak N, Rojas V, Patel S, Vaish R, Koruza J, Rossetti G Jr, Rödel J. BaTiO3-based piezoelectrics: fundamentals, current status, and perspectives. Appl Phys Rev. 2017;4: 041305.

[63] Yarin AL, Pourdeyhimi B, Ramakrishna S. Fundamentals and applications of micro- and nanofibers. Cambridge: Cambridge University Press; 2014.

[64] Tang C, Liu H. Cellulose nanofiber reinforced poly(vinyl alcohol) composite film with high visible light transmittance. Compos A. 2008;39:1638.

[65] An S, Liou M, Song KY, Jo HS, Lee MW, Al-Deyab SS, Yarin AL, Yoon SS. Highly flexible transparent self-healing composite based on electrospun core–shell nanofibers produced by coaxial electrospinning for anti-corrosion and electrical insulation. Nanoscale. 2015;7:17778.

[66] Lee HJ, An S, Hwang JH, Jung S-G, Jo HS, Kim KN, Shim YS, Park CH, Yoon SS, Park YW. Novel composite layer based on electrospun polymer nanofibers for efficient light scattering. ACS Appl Mater Interfaces. 2015;7:68.

[67] An S, Jo HS, Kim YI, Song KY, Kim M-W, Lee KB, Yarin AL, Yoon SS. Bio-inspired, colorful, flexible, defrostable light-scattering hybrid films for the effective distribution of LED light. Nanoscale. 2017;9:9139.

[68] Zubko P, Catalan G, Tagantsev AK. Flexoelectric effect in solids. Annu Rev Mater Res. 2013;43:387.

[69] Huang S, Kim T, Hou D, Cann D, Jones JL, Jiang X. Flexoelectric characterization of BaTiO3–0.08Bi(Zn1/2Ti1/2)O3. Appl Phys Lett. 2017;110:222904.

[70] Yudin P, Tagantsev A. Fundamentals of flexoelectricity in solids. Nanotechnology. 2013;24: 432001.

[71] Xu T, Wang J, Shimada T, Kitamura T. Direct approach for flexoelectricity from first-principles calculations: cases for SrTiO3 and BaTiO3. J Phys Condens Matter. 2013;25:415901.

[72] Catalan G, Sinnamon LJ, Gregg JM. The effect of flexoelectricity on the dielectric properties of inhomogeneously strained ferroelectric thin films. J Phys Condens Matter. 2004;16:2253.

[73] Cross LE. Flexoelectric effects: charge separation in insulating solids subjected to elastic strain gradients. J Mater Sci. 2006;41:53.

[74] Chen N, Koker MKA, Uzun S, Silberstein MN. In-situ X-ray study of the deformation mechanisms of non-woven polypropylene. Int J Solids Struct. 2016;97–98:200.

[75] Xu H, Gao L, Guo J. Preparation and characterizations of tetragonal barium titanate powders by hydrothermal method. J Eur Ceram Soc. 2002;22:1163.

[76] Cui Y, Briscoe J, Dunn S. Effect of ferroelectricity on solar-light-driven photocatalytic activity of BaTiO3 influence on the carrier separation and stern layer formation. Chem Mater. 2013;25:4215.

[77] Meng N, Zhu X, Mao R, Reece MJ, Bilotti E. Nanoscale interfacial electroactivity in PVDF/PVDF-TrFE blended films with enhanced dielectric and ferroelectric properties. J Mater Chem C. 2017;5:3296.

[78] Baji A, Mai Y-W, Li Q, Liu Y. Electrospinning induced ferroelectricity in poly (vinylidene fluoride) fibers. Nanoscale. 2011;3:3068.

[79] Soulestin T, Ladmiral V, Dos Santos FD, Ameduri B. Vinylidene fluoride-and trifluoroethylene-containing fluorinated electroactive copolymers. How does chemistry impact properties? Prog Polym Sci. 2017;72:16.

[80] Dutta S, Buragohain P, Glinsek S, Richter C, Aramberri H, Lu H, Schroeder U, Defay E, Gruverman A, Íñiguez J. Piezoelectricity in hafnia. Nat Commun. 2021;12:7301.

[81] Buragohain P, Lu H, Richter C, Schenk T, Kariuki P, Glinsek S, Funakubo H, Íñiguez J, Defay E, Schroeder U. Quantification of the Electromechanical Measurements by Piezoresponse Force Microscopy. Adv Mater. 2022;34:2206237.

[82] Tang C, Liu H. Cellulose nanofiber reinforced poly (vinyl alcohol) composite film with high visible light transmittance. Compos A. 2008;39:1638.

[83] Sato H, Iba H, Naganuma T, Kagawa Y. Effects of the difference between the refractive indices of constituent materials on the light transmittance of glass-particle-dispersed epoxy-matrix optical composites. Philos Mag B. 2002;82:1369.

[84] Motakef S, Suratwala T, Roncome R, Boulton J, Teowee G, Uhlmann D. Processing and optical properties of inorganic-organic hybrids (polycerams). II. PDMS-based waveguides. J Non-Cryst Solids. 1994;178:37.

[85] Bai M. The structure of ferroelectric polyvinylidene fluoride/trifluoroethylene (PVDF/TrFE) copolymer Langmuir-Blodgett films. Lincoln: The University of Nebraska-Lincoln; 2002.

[86] Karvounis A, Timpu F, Vogler-Neuling VV, Savo R, Grange R. Barium titanate nanostructures and thin films for photonics. Adv Opt Mater. 2020;8:2001249.

[87] Wang M, Bonfield W. Chemically coupled hydroxyapatite-polyethylene composites: structure and properties. Biomaterials. 2001;22:1311.

[88] Ye H, Lam H, Titchenal N, Gogotsi Y, Ko F. Reinforcement and rupture behavior of carbon nanotubes–polymer nanofibers. Appl Phys Lett. 2004;85:1775.

[89] Ku H, Wang H, Pattarachaiyakoop N, Trada M. A review on the tensile properties of natural fiber reinforced polymer composites. Compos B. 2011;42:856.

[90] Tian M, Gao Y, Liu Y, Liao Y, Xu R, Hedin NE, Fong H. Bis-GMA/TEGDMA dental composites reinforced with electrospun nylon 6 nanocomposite nanofibers containing highly aligned fibrillar silicate single crystals. Polymer. 2007;48:2720.

[91] Shashoua VE. Static electricity in polymers. I. Theory and measurement. J Polym Sci. 1958;33:65.

[92] Horn RG, Smith DT. Contact electrification and adhesion between dissimilar materials. Science. 1992;256:362.

[93] Wu C, Wang AC, Ding W, Guo H, Wang ZL. Triboelectric nanogenerator: a foundation of the energy for the new era. Adv Energy Mater. 2019;9:1802906.

[94] Yang X, Daoud WA. Triboelectric and piezoelectric effects in a combined tribo-piezoelectric nanogenerator based on an interfacial ZnO nanostructure. Adv Funct Mater. 2016;26:8194.

[95] Wang X, Yang B, Liu J, Yang C. A transparent and biocompatible single-friction-surface triboelectric and piezoelectric generator and body movement sensor. J Mater Chem A. 2017;5:1176.

[96] Ma M, Zhang Z, Zhao Z, Liao Q, Kang Z, Gao F, Zhao X, Zhang Y. Self-powered flexible antibacterial tactile sensor based on triboelectric-piezoelectric-pyroelectric multi-effect coupling mechanism. Nano Energy. 2019;66: 104105.

[97] Huang T, Zhang Y, He P, Wang G, Xia X, Ding G, Tao TH. “Self-matched” tribo/piezoelectric nanogenerators using vapor-induced phase-separated poly(vinylidene fluoride) and recombinant spider silk. Adv Mater. 2020;32:1907336.

[98] Shawon SMAZ, Sun AX, Vega VS, Chowdhury BD, Tran P, Carballo ZD, Tolentino JA, Li J, Rafaqut MS, Danti S. Piezo-tribo dual effect hybrid nanogenerators for health monitoring. Nano Energy. 2021;82: 105691.

[99] Do YH, Jung WS, Kang MG, Kang CY, Yoon SJ. Preparation on transparent flexible piezoelectric energy harvester based on PZT films by laser lift-off process. Sens Actuators A. 2013;200:51.

[100] Fuh YK, Kuo CC, Huang ZM, Li SC, Liu ER. A transparent and flexible graphene-piezoelectric fiber generator. Small. 1875;2016:12.

[101] Hu C, Cheng L, Wang Z, Zheng Y, Bai S, Qin Y. A transparent antipeep piezoelectric nanogenerator to harvest tapping energy on screen. Small. 2016;12:1315.

[102] Kim K, Ha M, Choi B, Joo SH, Kang HS, Park JH, Gu B, Park C, Park C, Kim J. Biodegradable, electro-active chitin nanofiber films for flexible piezoelectric transducers. Nano Energy. 2018;48:275.

[103] Shepelin NA, Lussini VC, Fox PJ, Dicinoski GW, Glushenkov AM, Shapter JG, Ellis AV. 3D printing of poly(vinylidene fluoride-trifluoroethylene): a poling-free technique to manufacture flexible and transparent piezoelectric generators. MRS Commun. 2019;9:159.

[104] Shepelin NA, Sherrell PC, Goudeli E, Skountzos EN, Lussini VC, Dicinoski GW, Shapter JG, Ellis AV. Printed recyclable and self-poled polymer piezoelectric generators through single-walled carbon nanotube templating. Energy Environ Sci. 2020;13:868.

[105] Yu X, Liang X, Krishnamoorthy R, Jiang W, Zhang L, Ma L, Zhu P, Hu Y, Sun R, Wong C-P. Transparent and flexible hybrid nanogenerator with welded silver nanowire networks as the electrodes for mechanical energy harvesting and physiological signal monitoring. Smart Mater Struct. 2020;29: 045040.

[106] Ng KE, Ooi PC, Haniff MASM, Goh BT, Dee CF, Chang WS, Wee MMR, Mohamed MA. Performance of all-solution-processed, durable 2D MoS2 flakes− BaTiO3 nanoparticles in polyvinylidene fluoride matrix nanogenerator devices using N-methyl-2-pyrrolidone polar solvent. J Alloys Compd. 2020;820: 153160.

[107] Eom K, Na S, Kim J-K, Ko H, Jin J, Kang SJ. Engineering crystal phase of Nylon-11 films for ferroelectric device and piezoelectric sensor. Nano Energy. 2021;88: 106244.

[108] Rodrigues-Marinho T, Pereira N, Correia V, Miranda D, Lanceros-Méndez S, Costa P. Transparent piezoelectric polymer-based materials for energy harvesting and multitouch detection devices. ACS Appl Electron Mater. 2021;4:287.

[109] Kim K, Lee S, Nam JS, Joo M, Mikladal B, Zhang Q, Kauppinen EI, Jeon I, An S. Highly transparent and mechanically robust energy-harvestable piezocomposite with embedded 1D P(VDF-TrFE) nanofibers and single-walled carbon nanotubes. Adv Funct Mater. 2023;33:2213374.