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Control of Charge Separation and Nonradiative Recombination in Host–Guest Azabuckybowl@C60 by Tweezer Linker Substitutions
To forecast more active photovoltaic materials, the recent effort has concentrated on the charge transfer dynamics in host–guest systems. Charge carrier dynamics of buckybowl-substituted phenanthrenes in azabuckybowl@C60 hybrids have been investigated employing nonadiabatic molecular dynamics within the density-based tight-binding framework. Our investigation shows 3,6-azabuckybowl@C60 exhibits quicker electron transfer of 803 fs, well corroborated with experiment. Whereas 2,7-azabuckybowl@C60 produces an ultrafast electron transfer (250 fs) by lowering torsional angles between linker and azabuckybowl from ∼60° to ∼19°, which enhances orbital overlap with small band offset relative to 3,6-azabuckybowl@C60. The 3,6-positions of phenanthrene functions as rigid lever arms that rotate sharply about 60° whereas the 2,7-positions require an out-of-plane rotation because of congestion and reduce torsional angle. Furthermore, widening the band gap with weak nonadiabatic coupling, 2,7-azabuckybowl@C60 shows delayed electron–hole recombination (12 ns) compared to 3,6-azabuckybowl@C60 (8.3 ns), signifying its potential as a more effective photovoltaic device and facilitating host–guest studies.