To tailor organic p/n heterojunctions with molecular-level precision, a rational design strategy using side-chain incompatibility of a covalently connected donor-acceptor (D-A) dyad has been successfully carried out. An oligothiophene-perylenediimide dyad, when modified with triethylene glycol side chains at one terminus and dodecyl side chains at the other (2Amphi), self-assembles into nanofibers with a long-range D/A heterojunction. In contrast, when the dyad is modified with dodecyl side chains at both termini (2Lipo), ill-defined microfibers result. In steady-state measurements using microgap electrodes, a cast film of the nanofiber of 2Amphi displays far better photoconducting properties than that of the microfiber of 2Lipo. Flash-photolysis time-resolved microwave conductivity measurements, in conjunction with transient absorption spectroscopy, clearly indicate that the nanofiber of 2Amphi intrinsically allows for better carrier generation and transport properties than the microfibrous assembly of 2Lipo.
ASJC Scopus subject areas
- Organic Chemistry