Endohedral and exohedral fullerenes have both been employed as electron acceptors in polymer solar cells (PSCs). However, their differences in hot-electron relaxation dynamics remain unclear. Previous studies have shown that the location of a single atom, whether inside or outside the fullerene cage, results in significant differences in charge distribution. In this work, the hot-electron relaxations of endohedral B@C60+ and exohedral C60B+ are investigated using nonadiabatic molecular dynamics simulations. Our results reveal that the location of the boron atom-inside or outside the fullerene-significantly impacts the bonding interactions between boron and C60. Compared to C60B+, the weaker interactions in B@C60+ reduce the orbital overlap between LUMO+3 and LUMO+2 and increase the energy gap between them. This, in turn, slows hot-electron relaxation by weak nonadiabatic coupling, making B@C60+ more suitable for PSC applications. This study provides valuable insights into how atomic positioning affects the electronic properties in fullerene-based materials, contributing to the design of more efficient electron acceptors for photovoltaic devices.
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