Pyroelectric and conduction properties of Z-type calix[4] acid Langmuir-Blodgett films

Abstract

Non-centrosymmetric Z-type Langmuir-Blodgett (LB) films were prepared by transferring a calix[4] acid monolayer from a subphase of Millipore water (18 M Omega cm(-1)) onto aluminised glass substrates. Electrical measurements were performed at room temperature on LB films with a sandwich structure comprising a 50 nm thick thermally evaporated aluminium film. A pyroelectric figure of merit of 2.23 mu C m(-2)K(-1) is reported for this LB system. The low voltage value of conductivity is 1.82 x 10(-12) S m(-1). The electrode-limited Schottky effect is responsible for the conduction mechanism at a relatively high field due to the dc bias and the barrier potential height is determined to be 1.72 eV. The ac conductance for both samples shows a typical power law dependence with a value of approximate to 0.86 for the exponent.