A series of liquid crystalline organic dyes consisting of fluorenyl hexa-peri-hexabenzocoronene (FHBC) and diketopyrrolopyrrole (DPP) units was synthesised and characterised. Their thermotropic behaviour is a result of the strong π–π association between FHBC units while the DPP unit enhances light absorption. With small changes in the molecular structure, significant differences in molecular organisation were observed in solid state. In turn, the molecular arrangement led to variations in the semiconducting properties of these materials and, ultimately, their performance in organic solar cells.