journal homepage: www.elsevier.com/locate/nanoenergy Available online at www.sciencedirect.com RAPID COMMUNICATION Flexible piezoelectric nanogenerator made of poly (vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE) thin film Zhaoyang Pi a , Jingwei Zhang a , Chenyu Wen a , Zhi-bin Zhang b , Dongping Wu a,n a State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai, China b Solid-State Electronics, The Ångström Laboratory, Uppsala University, P.O. Box 534, 75121 Uppsala, Sweden Received 3 April 2014; accepted 21 April 2014 Available online 30 April 2014 KEYWORDS Flexible; Nanogenerator; Thermopoling; PVDF-TrFE; Energy scavenging; Self-powered Abstract In this paper, a flexible nanogenerator based on direct piezoelectric effect using a spin-coated poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE) thin film as functional layer has been fabricated on polyimide substrate. The as-prepared nanogenerator exhibits the open-circuit voltage up to 7 V and short-circuit current of 58 nA with current density of 0.56 μA/cm 2 . The impact of the variation of strain rate on the electrical outputs of the nanogenerator has been characterized experimentally and analyzed theoretically. An analytical model that explains well the experimental results has been established. & 2014 Elsevier Ltd. All rights reserved. Introduction Effective conversion of mechanical energy into electricity is of pivotal importance for self-powered electronic devices and systems [1–4]. Many efforts have been exerted to develop the energy scavenging techniques based on different effects and mechanisms, such as electrostatics [5,6], elec- tromagnetics [7,8], and piezoelectricity [9,10]. Piezoelectric energy scavenging nanogenerators (NGs) based on ZnO [11], PZT [12] and BaTiO 3 [13] have received great attention. Although piezoelectric ZnO nanowires have until now been the most outstanding candidate for self-powered and novel nanostructures [14,15], their low piezoelectric coefficient (12 pC/N) [16] is the major hindrance to increase open- circuit voltage and short-circuit current. Inorganic materials with high piezoelectric coefficient such as PZT (200 pC/N) http://dx.doi.org/10.1016/j.nanoen.2014.04.016 2211-2855/& 2014 Elsevier Ltd. All rights reserved. n Corresponding author. Tel./fax: + 86 21 55665243. E-mail address: dongpingwu@fudan.edu.cn (D. Wu). Nano Energy (2014) 7, 33–41