Pyroelectric Properties of the B-Polyvilnylidene Fluoride (PVDF) Thin Film Prepared by Vacuum Deposition with Electric Field Application

Abstract

Polyvinylidene fluoride (PVDF) thin film having β phase is prepared by vacuum deposition with electric field application and its pyroelectric properties are studied using a dynamic method to examine the possibility of its application to a pyroelectric IR sensor. The pyroelectric responses of the PVDF thin film are characterized as the frequency dispersion in both low and high modulation frequency regions, and their frequency dependences are observed. In the low frequency region (2-100 Hz), the polarization can easily rotate with the increase of modulation frequency and show the maximum since the reorientation rate of domains is higher than the modulation frequency. On the other hand, in the high frequency region (100-1000 Hz), the pyroelectric response decreases as the frequency increases, because the reorientation rate of domains is suppressed and thus, the change of polarization decreases. Pyroelectric coefficient, figure of merits for noise equivalent power and detectivity of the PVDF thin film are measured as 4.39×10 −9 C/cm 2 ·K, 7.72×10 −10 C·cm/J, and 2.29×10 −9 C·cm/J, respectively. Also, the noise equivalent and the detectivity are 1.66 × 10 −7 W/Hz 1/2 , and 6.03 × 10 5 cm·Hz 1/2 /W, respectively.

Highly Sensitive and Multifunctional Tactile Sensor Using Free-standing ZnO/PVDF Thin Film with Graphene Electrodes for Pressure and Temperature Monitoring

“…The piezoelectric and pyroelectric properties of PVDF are strongly dependent on the β -phase content, owing to large net dipole moment, which originates from the all-trans structure 4 34 . Therefore, Fourier transform infrared (FTIR) spectroscopy was carried out to investigate the strong dielectric potential, based on the ratio of the α and β phases ( I β /I α ), and the fraction of the β phase, as shown in Fig.…”

“…We found that the response was slower, and the recovery time longer, at higher temperatures. This is because the pyroelectricity originated from the PVDF, and the thermal energy released from the heated weight on the surface of PVDF thin film resulted in slower motion of the dipoles 15 34 41 42 43 44 . Loading at 20°C resulted in a recovery time of 190 ms, loading at 70°C resulted in a recovery time of 680 ms, and loading at 120°C in a recovery time of 1150 ms.…”

Coupling between Pyroelectricity and Built-In Electric Field Enabled Highly Sensitive Infrared Phototransistor Based on InSe/WSe2/P(VDF-TrFE) Heterostructure

“…The larger the detectivity, the better it is for obtaining signals out of noises. As shown in Supplementary Note 3, the calculated detectivity for 633 nm laser illumination can reach up to about 10 13 Jones, and IR radiation with the photon energy below the band gap of the constituent 2D materials is up to 10 11 Jones of magnitude (Supplementary Note 5 and Figure S7), which is much better than all the previous reports of pyroelectric IR detectors, including 2D materials. − For example, the pyroelectric IR detector base on graphene/PVDF has a detectivity of only 7.42 × 10 6 Jones . The origin of the enhanced photosensitivity can be attributed to the uniqueness of the coupling between the pyroelectricity and the built-in electric field across the p–n junction.…”

Multimodal Sensors with Decoupled Sensing Mechanisms

“…For example, polyvinylidene fluoride (PVDF) with inherent pyroelectric and piezoelectric effects that depend on the polarization and the dipole moment can be used for sensing temperature and pressure in bimodal sensors. The temperature‐induced movement of the dipoles is slower [ 94 ] to give increased response/recovery times, compared to that from the applied pressure, which can be leveraged to separate temperature and pressure. Furthermore, the addition of zinc oxide (ZnO) increased permittivity can enhance the pyroelectric and piezoelectric properties of PVDF due to increased polarization and dipole moment.…”