Langmuir-Blodgett films: a new class of pyroelectric materials

The authors report on a novel method for producing the noncentrosymmetric structures necessary for the observation of the pyroelectric effect. The Langmuir-Blodgett technique has been used to fabricate ultrathin films consisting of alternate layers of 22-tricosenoic acid and 1-docosylamine. The pyroelectric coefficient has been determined using both static and dynamic detection techniques, is approximately 0.2 nC cm(-2) K(-1) (static value); this value is independent of the film thickness in the range of 11 to 99 monolayers, but increases slightly if a substrate of lower thermal expansion coefficient is used. The results indicate that there is a piezoelectrically induced secondary effect contributing to the overall pyroelectric activity.