  A novel, computationally designed, class of triangular-shape organic
molecules with an inverted singlet-triplet (IST) energy gap is investigated
with the aid of ab initio methods of electronic structure theory. The
considered molecular systems have a form of cyclic oligomers and their common
feature is electronic conjugation localized along the molecular rim. Analysis
of vertical transition energies from the electronic ground state, as well as
from the lowest excited singlet and triplet states of selected molecules, is
conducted. The results underscore the significance of optimizing excited-state
geometries in theoretical models to accurately describe the optoelectronic
properties of the IST molecules, particularly in relation to their applications
in OLEDs.
