OPTIMIZATION OF THERMAL PERFORMANCE OF LANGMUIR-BLODGETT-FILM PYROELECTRIC DEVICES

We report attempts to improve the low frequency responsivity of Langmuir-Blodgett (LB) film pyroelectric devices. Replacing the conventional glass substrate (300 mu m) with a thin polymer (1. 5 mu m) gave an improvement by a factor of greater than 3 at 4 Hz. Reduction in the ambient pressure to below 10** minus **1 mbar produced improvement by another factor of 2 and a response proportional to omega ** minus **1, as predicted by simple theory. The calculated pyroelectric coefficient rho is still smaller by a factor of 15 than that measured by a charge integration technique. A possible explanation is offered in terms of the secondary nature of the pyroelectric effect in the LB film and mechanical constraint of thermal expansion of the film by the tension in the polymer substrate.