The use of ternary
organic semiconducting blends is recognized
as an effective strategy to boost the performance of polymer solar
cells (PSCs) by increasing the photocurrent while minimizing voltage
losses. Yet, the scarcity of suitable donors with a deep highest occupied
molecular orbital (HOMO) level poses a challenge in extending this
strategy to ternary systems based on two polymers. Here, we address
this challenge by the synthesis of a new donor polymer (PM7-Si), which
is akin to the well-known PM6 but has a deeper HOMO level. PM7-Si
is utilized as the third component to enhance the performance of the
best-in-class binary system of PM6:BTP-eC9, leading to simultaneous
improvements in the efficiency (17.7%), open-circuit voltage (0.864
V), and fill factor (77.6%). These decisively enhanced features are
attributed to the efficient carrier transport, improved stacking order,
and morphology. Our results highlight the use of two polymer donors
as a promising strategy toward high-performance ternary PSCs.
Small band gap molecular semiconductors are of interest for the development of transparent electronics. Here we report two near-infrared (NIR), n-type small molecule semiconductors, based upon an acceptor−donor−acceptor (A-D-A) approach. We show that the inclusion of molecular spacers between the strong-electron-accepting end group, 2,1,3benzothiadiazole-4,5,6-tricarbonitrile, and the donor core affords semiconductors with very low band gaps down to 1 eV. Both materials were synthesized by a one-pot, 6-fold nucleophilic displacement of a fluorinated precursor by cyanide. Significant differences in solid-state ordering and charge carrier mobility are observed depending on the nature of the spacer, with a thiophene spacer resulting in solution processed organic field-effect transistors (OFETs) exhibiting excellent electron mobility up to 1.1 cm 2 V −1 s −1 . The use of silver nanowires as the gate electrode enables the fabrication of a semitransparent OFET device with an average visible transmission of 71% in the optical spectrum.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.