Simply tuning the electron deficient units to achieve P[sbnd] and N-type conjugated polymers for organic solar cells

Abstract

D-A strategy and noncovalent conformational locks (NCLs) have been employed as important tools to construct highly performing conjugated polymers (CPs). In this work, a donor (D) unit (E)-1,2-diethoxy-1,2-bis(5-(trimethylstannyl)thieno[3,2-b]thiophen-2-yl)ethene (FS) with S⋯O NCLs was copolymerized with four different acceptor (A) units. Upon changing the electron deficient properties of the A unit, the electronic properties of the CPs were successfully tuned to afford two p-type CPs and two n-type CPs. The optical absorption, electrochemical properties, molecular geometries, photovoltaic properties, charge transport characteristics, and morphology of these polymers and corresponding devices were systematically investigated. P-type polymer PffBT2T-FS and n-type polymer PPDI-FS based devices achieved PCEs as high as 5.03% and 3.23%, respectively. This contribution provides a synthetic strategy for constructing novel high-performance CPs.