Single crystal organic field-effect transistors (FETs) based on highly luminescent oligo(p -phenylenevinylene) (OPV) derivatives are fabricated. Although OPV single crystal FETs show both p - and n - type FET operation, we found that an increase in the conjugation length of the OPV derivatives from three phenylene rings (P3V2) to four phenylene rings (P4V3) results in an improvement in the electron mobility by an order of magnitude, while retaining the high hole mobility. This molecular design, using P4V3, achieved an ambipolar light-emitting OFET with well-balanced high hole (0.12 cm2 /V s) and electron (0.11 cm2 /V s) mobilities, leading to intense electroluminescence.
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