Polyurea spin-coated thin films: Pyro- and piezoelectric properties and application to infrared sensors

Abstract

We have investigated the pyro- and piezoelectric properties of polyurea spin-coated films with thermal and chemical stability and their performance as infrared sensors. The piezoelectric coefficient d33 was measured by a laser Doppler vibrometer to be 23.5 pC/N. This coefficient increased with the poling electric field up to around 75MV/m, suggesting that the polyurea dipole is aligned by applying an electric field greater than 75MV/m. When a triangular thermal wave was applied, a square-wave pyroelectric current was observed and the pyroelectric coefficient measured to be 5.11 μC/(m2·K). The infrared sensor performance of the polyurea thin film was examined by measuring the voltage sensitivity to infrared irradiation. The obtained result of 70.4V/W at 1Hz is consistent with the results calculated from the measured pyroelectric coefficient. Our findings suggest that the performance of the sensor may be improved by increasing the pyroelectric coefficient of the polyurea films.