Towards β-phase formation probability in spin coated PVDF thin films

This work aimed towards the study on variations in the percentage of beta-phase in Poly vinylidene fluoride (PVDF) thin films deposited by spin coating technique. PVDF is a semi-crystalline polymer which exhibits alpha, beta, gamma and delta polymorphs. Among these polymorphs, generally it crystallizes in a non-polar alpha-phase, which is of little importance as far as its applications are concerned. However, the beta-phase, which exhibits spontaneous polarity created tremendous interest and showed a path towards the devices based on its pyro-and piezoelectric properties. Fourier Transform Infrared (FTIR) spectroscopy and XRD techniques were used to study the percentage of formation of beta-phase in spin coated PVDF thin films at different processing conditions viz. spin rotation speed (rpm), solution concentration and annealing temperature. We identified the beta-phase percentage in PVDF thin films, which are (i) Deposited with different rotation speeds ranging from 1000 to 9000 rpm, (ii) Annealed at different temperatures viz.; room temperature to 100C, and (iii) Deposited at various solution concentrations. It is identified that percentage of formation of beta-phase is high in the films deposited with 15(w/v)% solution concentration which is annealed at 100C. The films deposited at higher rpm is showing low enhancement in the beta-phase with annealing temperature.