Doping effect on photoabsorption and charge-separation dynamics in light-harvesting organic molecule

Abstract

Using ab-initio theoretical methods, we demonstrate possible enhancement of photo-conversion efficiency of an organic solar cell via intentional doping in molecular graphene-fullerene heterojunction [the hexabenzocoronene (HBC)-triethylene glycol (TEG)–C60 molecule]. Photoabsorption analysis indicates oxygen substitution into HBC leads to an extension of the spectra up to an infrared regime. A quantum-mechanical molecular dynamics simulation incorporating nonadiabatic electronic transitions reveals that a dissociated charge state (D+ and A-) in the O-doped system is more stable than the pristine case due to the presence of an effective barrier by the TEG HOMO/LUMO level. We also find that oxygen doping in HBC enhances the intermolecular carrier mobility after charge separation. On the other hand, the pristine molecule undergoes rapid recombination between donor and acceptor charges at the interface. These analyses suggest that the graphene oxidation opens a new window in the application of organic super-molecules to solar cells.

Femtosecond charge and molecular dynamics of I-containing organic molecules induced by intense X-ray free-electron laser pulses

“…We have previously applied it to investigate charge transfer in several photo-excited organic molecules. [56][57][58][59] In the present study, we extend the method to the charge dynamics in 5-IU molecular ions with many holes.…”

Electronic friction in interacting systems

“…In particular, the interactions are central to spectroscopy [1][2][3][4], bias-induced [5,6] and photo-chemistry [7], electron [8] and energy [9][10][11][12] transfer, coherent control [13], radiative [14] and non-radiative [15] electronic relaxation, and stability of junctions [16][17][18][19][20]. Understanding mechanisms of the interactions and developing theoretical description is crucial for engineering optoelectronic [21,22] and optomechanical [23] molecular devices.…”

Current-Induced Forces for Nonadiabatic Molecular Dynamics

“…Nonadiabatic molecular dynamics (NAMD) is a fundamental problem related to breakdown of the usual time scale separation (the Born–Oppenheimer approximation) between electron and nuclear dynamics. NAMD plays an important role in many processes, ranging from chemistry , and photochemistry to spectroscopy − and nonradiative electronic relaxation and from electron and proton transfer − to coherent control and photoinduced energy transfer. , The significance of the problem stems from both the complexity of its fundamental theoretical description and applicational importance for development of optoelectronic , and optomechanical molecular devices.…”

“…The NAMD plays an important role in many processes, ranging from chemistry [1,2] and photochemistry [3] to spectroscopy [4][5][6][7] and nonradiative electronic relaxation [8], and from electron and proton transfer [9][10][11] to coherent control [12] and photo-induced energy transfer [13,14]. Significance of the problem stems from both complexity of it fundamental theoretical description, and applicational importance for development of optoelectronic [15,16] and optomechanical [17] molecular devices.…”