The introduction of heteroatoms into electron-deficient scaffolds is a compelling strategy to tune their properties. Herein we show how the ortho O-annulation of AzaBPDIs and BACDs shrinks their optical gaps by uplifting their HOMO energies along with their LUMO energies in a less pronounced way. Such derivatives seem to be highly sensitive to the nature of the new ring fused to their core as the naphthalene appended derivative 4 shows a significant red-shift of its absorption compared to the phenyl-annulated 2a and 2b. Their preliminary use in organic electronic devices such as OSCs and OFETs demonstrates that more complex O-annulated rylene diimide structures are worth investigating to extend this so far small family of n-type organic semiconductors.