Organic semiconductors (OSCs) consist of connected conjugated systems, where electron delocalisation gives rise to semiconducting properties. With applications in organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), and organic photovoltaics (OPVs), they hold promises such as light-weight and transparent electronics and cheap manufacturing through printing technologies. In this thesis, a much less common conjugated system is in focus: carborane. Carboranes are atomic clusters consisting of carbon and boron held together via delocalised σ-bonds. This bonding motif gives rise to many properties typically seen in aromatic compounds, such as enhanced thermal and chemical stability. Carborane-containing conjugated compounds – where a π-conjugated system is substituted onto one or both of the carbon vertices – have received increasing attention over the past 15 years, much thanks to their intriguing emissive properties. However, few such compounds have been demonstrated for use in organic electronics.

Here, the syntheses of three sets of organic semiconductors are presented, incorporating each of the three C2B10H10 carboranyl isomers in the conjugated backbone. The materials include one set of p-type polymers, one set of n-type polymers, and one set of n-type small molecules. Their optoelectronic properties are thoroughly investigated, and the successful fabrication of OLED, OFET, and OPV devices employing these materials in the active layers demonstrates their suitability for organic electronics. Furthermore, a systematic comparison between carborane isomers highlights their effect on material properties and device performance. This thesis also introduces two novel n-type dopants as a strategy to improve OFET performance, which are also evaluated for use with carborane-containing OSCs. Although carborane-containing conjugated materials are unlikely contenders for the most common applications in organic electronics, this thesis demonstrates their potential in areas which may be out of reach for conventional OSCs. This includes the fabrication of near-infrared LEDs and solid-state radiation detectors, as is demonstrated herein.