Giant nonlinear optical response of fullerene polymer fragments: A DFT perspective

Organic π -conjugated materials exhibit exceptional nonlinear optical (NLO) properties due to their unique electronic structures, characterized by short response times and large NLO responses. Fullerene (C 60 ) is one of the few polymer species that possess a rich π -conjugated system, making it a promising material with significant NLO responses. In the present paper, we designed three C 60 polymer fragments and employed density functional theory to estimate their molecular static first and second hyperpolarizabilities. Compared to previously reported fullerene derivatives, the designed C 60 polymer fragments can exhibit notable second-order and third-order molecular NLO responses. The study shows that the hyperpolarizabilities and energy gaps of the investigated C 60 polymer fragments are greatly influenced by their topological structures and bonding modes. These findings provide new insights for the design of novel NLO materials based on C 60 polymers, and the realization of tunable NLO responses in C 60 cluster-based molecular systems, which may have significant applications in nanophotonic devices.