Enhanced Ultrafast Nonlinear Optical Properties of Cyclopentadiene-Thiophene-Fused Core Non-Fullerene Nanofilms via Benzene Ring Integration

Abstract: Inspired by the promising nonlinear optical (NLO) properties of acene-based and thiophene-containing materials, we investigate the enhancement achieved by incorporating a benzene ring into cyclopentadiene-thiophene fused cores, aligning with non-fullerene acceptors in solar cells. We examine two non-fullerene films, IHIC and ITIC-DM, using femtosecond transient absorption and Z-scan experiments to evaluate their ultrafast NLO properties. Our results demonstrate that ITIC-DM exhibits superior nonlinear absorption (NLA) and nonlinear refraction (NLR), attributed to enhanced π–π* transitions. ITIC-DM also exhibits a significant improvement in NLO properties compared to other high-performance organic thin films. This study provides a new strategy for designing high-performance nonlinear optical organic materials.