This thesis project details the use of direct (hetero)arylation (DHA) cross-coupling methods in the synthesis of π-conjugated organic materials. The materials are based on the A–π-core–A framework where A is an electron acceptor moiety, typically N-annulated perylene diimide (NPDI), and the π-core is a thiophene-based material with -H atoms sufficiently reactive for DHA activation. Chapter One introduces the DHA method and presents the proposed reaction mechanism and common reaction parameters. A summary of various functional organic materials synthesized via DHA methods is also given. In Chapter Two, the application of DHA to the functionalization of bithiophene material incorporating a phosphole moiety is presented. Focus is given to the NPDI-functionalized compound (NPDI)2Th2PO and its use as a non-fullerene acceptor in organic solar cells. This is followed up in Chapter Three with the synthesis via Stille coupling of a borane-functionalized species, (NPDI)2Th2B, and its properties and device performance are compared to the (NPDI)2Th2PO and (NPDI)2Th2 analogues. Due to the borane moiety, synthesis via DHA coupling was not possible. In Chapter Four, various DHA methods are screened for the functionalization of thieno[3,4-c]pyrrole-4,6-dione with NPDI ((NPDI)2TPD) and a detailed analysis of post-deposition treatments for the optimization of solid-state morphology is provided. Chapter Five expands upon the synthesis of tetrameric materials via DHA methods with focus on the synthesis and properties of (NPDI)4ThTh, where ThTh = thieno[3,2-b]thiophene. Chapter Six continues this work by detailing the attempts to synthesize the Se-annulated PDI analogue, (SePDI)4ThTh, via DHA methods. Chapter Seven further explores the DHA functionalization of SePDI by coupling with diketopyrrolopyrrole (DPP). The synthesis and characterization of SePDI–DPP–SePDI and SePDI–DPP–NPDI are given and their properties compared with the previously reported NPDI–DPP–NPDI. Chapter Seven also marks the conclusion of this thesis.