Phase composition, crystalline structure and piezoelectric properties of thin films of polyvinylidene fluoride obtained by the spin-coating method

Abstract The regularities of the formation of the structural state and the piezoelectric properties of PVDF films with a thickness of about 170 nm, obtained by spin-coating on glass substrates, are studied. Using the methods of IR spectroscopy, X-ray diffraction, and Raman spectroscopy, the dependences of the ratio of crystalline α- and β-phases on the initial acceleration and maximum substrate rotation speed are established. The optimal values of these parameters are found that provide the maximum concentration of the β phase (∼ 60 %) with spontaneous electric polarization. It was shown that in the films studied, the value of the piezoelectric coefficient d33, determined by the method of piezoresponse force microscopy, can take anomalously large values (up to 74 pm/V). This is due to the fixing effect of the glass substrate, which provides significant residual deformation of the polymer films.