Keywords: 

Perylene; D-π-A-π-D molecules; Intramolecular charge transfer; Fluorescence quantum yield; Stokes shift; Pd-catalyzed couplings; Optoelectronic materials

Highlights: 

• Perylene-based D-π-A-π-D molecules with thiophene and ethyne π-spacers.

• π-spacer tuning modulates ICT character, absorption, and emission properties.

• ICT absorption at 480–496 nm while emission at 562–620 nm.

• H-Th shows a large Stokes shift (4704 cm⁻¹) in THF due to flexible thiophene spacer.

• TD-DFT reveals reduced exciton binding and reorganization energy in H-Et.