Polymer solar cells (PSCs) have attracted great attention in the past decade, because of the advantages of simple device structure, light weight and capability to be fabricated into flexible and semitransparent devices. Recently, the nonfullerene n-type organic semiconductor (n-OS) (such as the low bandgap n-OS ITIC) acceptors have attracted great attention for their high photovoltaic performance. To match with the low bandgap ITIC acceptor, we developed a series of medium bandgap 2D- conjugated D-A copolymer donors based on bithienyl-benzodithiophene (BDTT) as donor unit and fluorobenzotriazole (FBTA) as acceptor unit. By side chain engineering (alkyl-thienyl, alkylthio-thienyl, trialkylsilyl-thienyl or alkyl-difluorothienyl substitution) on the thiophene conjugated side chains of the medium bandgap polymers, the power conversion efficiency (PCE) of the PSCs with the polymers as donor and ITIC as acceptor reached 9.26%5~11.63%6. By side chain isomerization of ITIC, the PCE of the nonfullerene PSCs was further improved to 11.77%~12.05%.
Member of Chinese Academy of Sciences (2013)
Fellow of Royal Society of Chemistry (2014)