Flexible Fiber Nanogenerator with 209 V Output Voltage Directly Powers a Light-Emitting Diode Long Gu, †,⊥ Nuanyang Cui, †,⊥ Li Cheng, † Qi Xu, † Suo Bai, † Miaomiao Yuan, † Weiwei Wu, † Jinmei Liu, † Yong Zhao, § Fei Ma, † Yong Qin,* ,†,‡ and Zhong Lin Wang* ,‡,∥ † Institute of Nanoscience and Nanotechnology, Lanzhou University, Lanzhou 730000, China ‡ Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100085, China § Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China ∥ School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245, United States *S Supporting Information ABSTRACT: On the basis of a vertically aligned ultralong Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) nanowire array fabricated using electrospinning nanofibers, we developed a new type of integrated nanogenerator (NG) with ultrahigh output voltage of 209 V and current density of 23.5 μA/cm 2 , which are 3.6 times and 2.9 times of the previous record values, respectively. The output electricity can be directly used to stimulate the frog’s sciatic nerve and to induce a contraction of a frog’s gastrocnemius. The NG can instantaneously power a commercial light-emitting diode (LED) without the energy storage process. KEYWORDS: Nanogenerator, high output, energy harvesting, PZT nanowires, electrospinning H arvesting clean and renewable energy from the environ- ment is an effective method to response the current energy crisis and power wide distributed nano/microdevices. As a novel energy collector, nanogenerator (NG) exhibits a number of features not shared by the traditional generators, that is, the ones based on ocean tide, river falls, and wind, etc. NG fabricated with piezoelectric nanomaterials can convert tiny and irregular environmental mechanical energy to electricity from sources such as air flowing, heart beating, and so on, which are more popular in our living environment compared to the energy source used for traditional generators as mentioned above. 1 Moreover, due to its small size the NG can be effectively integrated with the nano/microscale functional devices to form a self-powered system, which has potential applications in the internet of things, national security, biomedical, and industry areas. In order to improve its output, many attempts have been made ranging from altering piezoelectric materials, that is, ZnO, 2 GaN, 3 CdS, 4 PbZr 0.52 Ti 0.48 O 3 , 5,6 BaTiO 3 , 7 PVDF, 8 to different designs, such as lateral, 5,9,10 radial, 11 or vertical integrations. 2,6 Up to now, various kinds of self-powered functional systems have been realized, such as self-powered pH sensor, 9 UV sensor, 9 small liquid crystal display, 12 commercial laser diode, 6 pressure/ speed sensor, 13 environmental sensor, 14 and so on. Among these systems, many of them need an energy storage unit to make them work properly. This energy storage circuit adds much complexity to the self-powered system and hinders its capacity to work in different tough environments. Here, we report a simple approach of fabricating vertically ultralong Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) nanowire arrays from electrospinning fibers to make a high output NG. Benefiting from the ultralong length of vertical nanowires, the fabricated NG has a maximum output peak voltage of 209 V, which is much higher than the past record of 58 V. 2 Also, the NG can output a maximum peak current of 53 μA and current density of 23.5 μA/cm 2 , which is 2.9 times of the recent highest value of 8.13 μA/cm 2 . 15 The output power of our NG can be directly used to stimulate the frog’s sciatic nerve and induce a contraction of that frog’s gastrocnemius. Moreover, the NG can power a commercial light-emitting diode (LED) instantly without energy storage, which is a considerable progress for the development of self- powered devices. Previous studies have shown that high piezoelectric coefficient of the fabricating material and integrated parallel and serial connection designs are two major factors to effectively increase NG’s output. So, we use PZT, which possesses the highest piezoelectric coefficient, as our piezo- electric material and adopt a novel design based on ultralong aligned nanowires with length about 420 μm in order to get a high output NG. In fact, NG based on the arrays with longer nanowires is equivalent to NGs made up of stacked layers of shorter wires but it can get rid of the superfluous hard substrates and keep nanowire’s flexibility. This new method contains the following steps. First, using our reported method 16 that includes electrospinning the orientated nanofibers and suspending calcination techniques to prepare PZT nanofibers Received: September 23, 2012 Revised: November 2, 2012 Letter pubs.acs.org/NanoLett © XXXX American Chemical Society A dx.doi.org/10.1021/nl303539c | Nano Lett. XXXX, XXX, XXX−XXX