Hydrogen Bonding-Assisted Complete Ferroelectric β-Phase Conversion in Poly(vinylidene fluoride) Thin Films: Exhibiting an Excellent Memory Window and Long Retention.

Organic nonvolatile memory with low power consumption is a critical research demand for next-generation memory applications. Ferroelectric switching characteristics of poly(vinylidene fluoride) (PVDF) thin films modified with a trace amount of hydrated Cu salt (CuCl2·2H2O) are explored in the present study. Herein, a Cu salt-mediated PVDF (Cu/PVDF) thin film with preferential edge-on β-crystallites is fabricated through the orientation-controlled spin coating (OCSC) technique. This work proposes a convenient and effective approach to produce edge-on-oriented electroactive PVDF thin films with a high degree of polar β-phase, so as to realize the favorable switching under low operating voltages. Herein, chemically modified PVDF is anticipated to form a complex intermediate, which attains its stability by undergoing favorable hydrogen bonding that reorients the C-C structure of PVDF to obtain the β-conformation. Such information is verified by X-ray photoelectron spectroscopy (XPS). Grazing incidence Fourier transform infrared (GI-FTIR) spectroscopy revealed that the Cu salt incorporated into the PVDF matrix favored the formation of the electroactive β-phase with edge-on crystallite lamellae. Consequently, the Cu/PVDF thin film demonstrates a good contrast between electric field-assisted written and erased data bits in the piezoresponse force microscopy (PFM) phase image. Furthermore, to obtain the ferroelectric memory window, a metal-ferroelectric-insulator-semiconductor (MFIS) diode with Cu/PVDF as a ferroelectric layer has been fabricated. The capacitance-voltage (C-V) characteristic of the MFIS diode exhibits a memory window of 12 V with a long-term retention behavior (∼longer than 7 days). In a nutshell, we tried to represent a clear understanding of the interfacial interactions of the Cu salt with PVDF, which favor the edge-on formation that results in the promising low-voltage ferroelectric switching and excellent retention response, where any additional electrical poling and/or external stretching is completely possible to be ruled out, thus offering a new prospect for the evolution of devices with long-lasting nonvolatile memories.

[1]  Ajay Kumar,et al.  Lead-Free Perovskite Cs3Bi2I9-Derived Electroactive PVDF Composite-Based Piezoelectric Nanogenerators for Physiological Signal Monitoring and Piezo-Phototronic-Aided Strained Modulated Photodetectors. , 2022, Langmuir : the ACS journal of surfaces and colloids.

[2]  Ajay Kumar,et al.  3D printed ferroelectret with giant piezoelectric coefficient , 2022, Applied Physics Letters.

[3]  Ajay Kumar,et al.  Revisiting of δ−PVDF Nanoparticles via Phase Separation with Giant Piezoelectric Response for The Realization of Self-Powered Biomedical Sensors , 2022, Nano Energy.

[4]  S. Ghosh,et al.  Revisiting δ-PVDF based piezoelectric nanogenerator for self-powered pressure mapping sensor , 2021, Applied Physics Letters.

[5]  J. Jur,et al.  Airbrushed PVDF–TrFE Fibrous Sensors for E-Textiles , 2021, ACS Applied Electronic Materials.

[6]  D. Mandal,et al.  Piezo-phototronic Effect in Highly Stable CsPbI3-PVDF Composite for Self-Powered Nanogenerator and Photodetector , 2021, Nano Energy.

[7]  P. Wachulak,et al.  Surface Modification of PLLA, PTFE and PVDF with Extreme Ultraviolet (EUV) to Enhance Cell Adhesion , 2020, International journal of molecular sciences.

[8]  Shouke Yan,et al.  Self-polarized Poly(vinylidene fluoride) Ultrathin Film and Its Piezo/Ferroelectric Properties. , 2020, ACS applied materials & interfaces.

[9]  D. Roy,et al.  Interfacial Interaction of Absorbate Copper Phthalocyanine with PVDF based Ferroelectric Polymer Substrates: A Spectroscopic Study. , 2020, Langmuir : the ACS journal of surfaces and colloids.

[10]  J. Qiu,et al.  PVDF-Based Composition-Gradient Multilayered Nanocomposites for Flexible High-Performance Piezoelectric Nanogenerators. , 2020, ACS applied materials & interfaces.

[11]  Z. Ni,et al.  Nonvolatile Memory Based on Molecular Ferroelectric/Graphene Field Effect Transistor. , 2018, ACS applied materials & interfaces.

[12]  D. Satapathy,et al.  Influence of Microstructure on the Nanomechanical Properties of Polymorphic Phases of Poly(vinylidene fluoride). , 2018, The journal of physical chemistry. B.

[13]  A. Ferri,et al.  Nanoscale Investigations of α- and γ-Crystal Phases in PVDF-Based Nanocomposites. , 2018, ACS applied materials & interfaces.

[14]  S. Lanceros‐Méndez,et al.  Electroactive poly(vinylidene fluoride)-based structures for advanced applications , 2018, Nature Protocols.

[15]  Yulin Yang,et al.  Facile Fabrication of Cu2O Nanobelts in Ethanol on Nanoporous Cu and Their Photodegradation of Methyl Orange , 2018, Materials.

[16]  D. Mandal,et al.  Organo-Lead Halide Perovskite Induced Electroactive β-Phase in Porous PVDF Films: An Excellent Material for Photoactive Piezoelectric Energy Harvester and Photodetector. , 2018, ACS applied materials & interfaces.

[17]  T. Sung,et al.  PVDF based flexible piezoelectric nanogenerators using conjugated polymer:PCBM blend systems , 2017 .

[18]  M. Biesinger.  Advanced analysis of copper X‐ray photoelectron spectra , 2017 .

[19]  Y. Hishikawa,et al.  Characterization of Individual Hydrogen Bonds in Crystalline Regenerated Cellulose Using Resolved Polarized FTIR Spectra , 2017, ACS omega.

[20]  Yaquan Wang,et al.  Ethylene/ethane separation by CuCl/AC adsorbent prepared using CuCl2 as a precursor , 2016, Adsorption.

[21]  Jiyoul Lee,et al.  Pulse-modulated multilevel data storage in an organic ferroelectric resistive memory diode , 2016, Scientific Reports.

[22]  X. Liu,et al.  Exceptional dielectric properties of chlorine-doped graphene oxide/poly (vinylidene fluoride) nanocomposites , 2015 .

[23]  M. Dresselhaus,et al.  X‐Ray Spectroscopic Investigation of Chlorinated Graphene: Surface Structure and Electronic Effects , 2015 .

[24]  Jianchi Zhang,et al.  Solvent vapor annealing of ferroelectric P(VDF-TrFE) thin films. , 2014, ACS applied materials & interfaces.

[25]  Feng Yan,et al.  Solution-processable low-voltage and flexible floating-gate memories based on an n-type polymer semiconductor and high-k polymer gate dielectrics. , 2014, ACS applied materials & interfaces.

[26]  A. C. Lopes,et al.  Electroactive phases of poly(vinylidene fluoride) : determination, processing and applications , 2014 .

[27]  R. Zanoni,et al.  Electrochemically deposited ZnO films: an XPS study on the evolution of their surface hydroxide and defect composition upon thermal annealing , 2014, Journal of Solid State Electrochemistry.

[28]  D. Mandal,et al.  Simple synthesis of palladium nanoparticles, β-phase formation, and the control of chain and dipole orientations in palladium-doped poly(vinylidene fluoride) thin films. , 2012, Langmuir : the ACS journal of surfaces and colloids.

[29]  D. Mandal,et al.  The electroactive β-phase formation in Poly(vinylidene fluoride) by gold nanoparticles doping , 2012 .

[30]  H. Kohlstedt,et al.  Investigation of state retention in metal–ferroelectric–insulator–semiconductor structures based on Langmuir–Blodgett copolymer films , 2010 .

[31]  K. Kim,et al.  Crystalline Structure and Ferroelectric Response of Poly(vinylidene fluoride)/Organically Modified Silicate Thin Films Prepared by Heat Controlled Spin Coating , 2009 .

[32]  H. Ishiwara,et al.  Low-voltage operation and excellent data retention characteristics of metal-ferroelectric-insulator-Si devices based on organic ferroelectric films , 2009 .

[33]  D. Mandal,et al.  Electrical investigations on metal/ferroelectric/insulator/semiconductor structures using poly[vinylidene fluoride trifluoroethylene] as ferroelectric layer for organic nonvolatile memory applications , 2009 .

[34]  K. Kim,et al.  Direct Preparation of Nanoscale Thin Films of Poly(vinylidene fluoride) Containing β-Crystalline Phase by Heat-Controlled Spin Coating , 2008 .

[35]  Youn Jung Park,et al.  Spin cast ferroelectric beta poly(vinylidene fluoride) thin films via rapid thermal annealing , 2008 .

[36]  Youn Jung Park,et al.  Localized Pressure‐Induced Ferroelectric Pattern Arrays of Semicrystalline Poly(vinylidene fluoride) by Microimprinting , 2007 .

[37]  J. Scott,et al.  Applications of Modern Ferroelectrics , 2007, Science.

[38]  S. Desu,et al.  Ferroelectric poly(vinylidene fluoride) thin films grown by low-pressure chemical vapor polymerization , 2006 .

[39]  Yadong Jiang,et al.  Ferroelectric polymeric PVDF films prepared by ultrasonic atomization method , 2006 .

[40]  R. Waser,et al.  Low-voltage operation of metal-ferroelectric-insulator-semiconductor diodes incorporating a ferroelectric polyvinylidene fluoride copolymer Langmuir-Blodgett film , 2006 .

[41]  R. Gregorio.  Determination of the α, β, and γ crystalline phases of poly(vinylidene fluoride) films prepared at different conditions , 2006 .

[42]  S. Desu,et al.  Electrical properties of metal-ferroelectric-insulator-semiconductor structures based on ferroelectric polyvinylidene fluoride copolymer film gate for nonvolatile random access memory application , 2004 .

[43]  Stephen R. Forrest,et al.  The path to ubiquitous and low-cost organic electronic appliances on plastic , 2004, Nature.

[44]  Y. Chien,et al.  Mineralization of CCl4 with copper oxide. , 2001, Environmental science & technology.

[45]  Steve Scheiner,et al.  Fundamental Properties of the CH···O Interaction: Is It a True Hydrogen Bond? , 1999 .

[46]  R. Vasquez.  CuCl by XPS , 1993 .

[47]  Hari Singh Nalwa,et al.  RECENT DEVELOPMENTS IN FERROELECTRIC POLYMERS , 1991 .

[48]  T. Furukawa.  Ferroelectric properties of vinylidene fluoride copolymers , 1989 .

[49]  A. J. Lovinger.  Ferroelectric Polymers , 1983, Science.

[50]  Steven C. Roth,et al.  Electric‐field‐induced phase changes in poly(vinylidene fluoride) , 1978 .

[51]  Robert L. Miller,et al.  Single crystals of poly(vinylidene fluoride) , 1976 .

[52]  Masamichi Kobayashi,et al.  Molecular Conformation and Packing of Poly(vinylidene fluoride). Stability of Three Crystalline Forms and the Effect of High Pressure , 1972 .

[53]  D. C. Owsley,et al.  Cupric Halide Halogenations , 1965 .

[54]  Guo-Rong Li,et al.  Formation of ferroelectric domains in a copolymer P(VDF–TrFE) , 1992 .

[55]  J. Sakata,et al.  Preparation of organic thin films by an electrospray technique I. Crystal forms and their orientation in poly(vinylidene flouride) films , 1991 .