This study presents an approach where semi-empirical molecular orbital theory can be used to screen for desirable optical properties of conjugated organic materials including Organic Light Emitting Diode (OLED) molecules prior to more elaborate computational study or actual experiments. Band-gap, HOMO (for ionization potential), and LUMO (for electron affinity) orbital energies from the PM6 method can be adjusted by shifting vertically to reproduce experimental data or accurate calculated data of one reference molecule in the class, and then the shifting constants can be used to estimate properties for other molecules in the class. The approach was tested with five different subclasses of oligothiophene derivatives which have different end-capped groups. Error analyses indicate that this approach is nearly as accurate as TDDFT but cost significantly less. Published by Elsevier B.V.