Benzothiadiazole building units in solution-processable small molecules for organic photovoltaics

Significant progress has been made in the field of organic photovoltaics in the last decade and the rapid development of innovative organic semiconductor materials is one of the main driving forces. This review attempts to summarize recent advances with respect to solution-processable molecular semiconductors having 2,1,3-benzothiadiazole or its fluorine substituted derivatives as electron-accepting units published in the last few years. Semiconducting polymers containing BT units have shown attractive photovoltaic performance while the molecular ones still lag behind. The relationship between the structures, optoelectronic properties, and photovoltaic performance of these molecular semiconductors is discussed within this review.