Refractive index changes in polysilane films due to thermochromism

Abstract

A large change in refractive index of about 0.07 was found in polysilane (poly(di-n-hexylsilane)) after a thermal treatment. The change was coincident reversibly with the material's thermochromism, suggesting that a part of the origin is from a change in molecular polarizability, i.e., the σ-conjugation length, arising from a switching of the Si backbone conformation between trans-planar and random-helix. By incorporating a pigment film for optothermal energy conversion, a possible application in reversible information recording using near-infrared light irradiation has been demonstrated.