Chirality in Poly(phenylene-alt-bithiophene)s: A Comprehensive Study of Their Behavior in Film and Nonsolvents

Chiroptical Properties in Thin Films of π-Conjugated Systems

Chiral π-conjugated molecules provide new materials with outstanding features for current and perspective applications, especially in the field of optoelectronic devices. In thin films, processes such as charge conduction, light absorption, and emission are governed not only by the structure of the individual molecules but also by their supramolecular structures and intermolecular interactions to a large extent. Electronic circular dichroism, ECD, and its emission counterpart, circularly polarized luminescence, CPL, provide tools for studying aggregated states and the key properties to be sought for designing innovative devices. In this review, we shall present a comprehensive coverage of chiroptical properties measured on thin films of organic π-conjugated molecules. In the first part, we shall discuss some general concepts of ECD, CPL, and other chiroptical spectroscopies, with a focus on their applications to thin film samples. In the following, we will overview the existing literature on chiral π-conjugated systems whose thin films have been characterized by ECD and/or CPL, as well other chiroptical spectroscopies. Special emphasis will be put on systems with large dissymmetry factors (g_abs and g_lum) and on the application of ECD and CPL to derive structural information on aggregated states.

Electronic circular dichroism imaging (CDi) maps local aggregation modes in thin films of chiral oligothiophenes

A detailed investigation of the circular dichroism imaging (CDi) technique on thin films of a chiral 1,4-dialkoxyphenylene-based oligothiophene with outstanding chiroptical features revealed the primary role of local supramolecular structures.

Aggregation-induced circularly polarized luminescence of an (R)-binaphthyl-based AIE-active chiral conjugated polymer with self-assembled helical nanofibers

An AIE-active chiral conjugated polymer P-1 exhibited aggregation-induced circularly polarized luminescence. The TEM and AFM images show that P-1 self-assembled into helical nanofibers during aggregation.