Optical studies of chirality induced pi-conjugated polymer films*

We have studied the optical and magneto-optical properties of organic thin films consisting of π-conjugated polymers blended with chiral molecules, using absorption, electro-absorption (EA), circular dichroism (CD), and photoluminescence (PL) spectroscopies. Various film preparation methods have been used including spin-cast, drop-cast with slow and fast evaporation rate, and annealing at various temperatures. Some polymer/chiral molecule blends showed strong CD up to ~1.5 radians and chiral anisotropy, g-values up to 0.8. The strong CD was accompanied with circular PL emission with similar anisotropy. Other blends showed smaller CD depending on the mode of film deposition. The EA spectroscopy has been utilized to study the miscibility of the chiral molecule within the polymer matrix.