The energetics of electronhole separation at the prototypical donor-acceptor interface P3HT/PCBM is investigated by means of a combination of molecular dynamics simulations, quantum-chemical methods, and classical microelectrostatic calculations. After validation against semiempirical Valence Bond/Hartree-Fock results, microelectrostatic calculations on a large number of electron-hole (e-h) pairs allowed a statistical study of charge separation energetics in realistic morphologies. Results show that charge separation is an energetically favorable process for about 50% of interfacial e-h pairs, which provides a rationale for the high internal quantum efficiencies reported for P3HT/PCBM heterojunctions. Three effects contribute to overcome the Coulomb attraction between electron and hole: (i) favorable electrostatic landscape across the interface, (ii) electronic polarization, and (iii) interface-induced torsional disorder in P3HT chains. Moreover, the energetic disorder due to the PCBM polar group is shown to play a key role in increasing the dissociation probability.
Energetics of Electron–Hole Separation at P3HT/PCBM Heterojunctions / Gabriele D’Avino;Sébastien Mothy;Luca Muccioli;Claudio Zannoni;Linjun Wang;Jérôme Cornil;David Beljonne;Frédéric Castet. - In: JOURNAL OF PHYSICAL CHEMISTRY. C. - ISSN 1932-7447. - STAMPA. - 117:(2013), pp. 12981-12990. [10.1021/jp402957g]
Energetics of Electron–Hole Separation at P3HT/PCBM Heterojunctions
MUCCIOLI, LUCA;ZANNONI, CLAUDIO;
2013
Abstract
The energetics of electronhole separation at the prototypical donor-acceptor interface P3HT/PCBM is investigated by means of a combination of molecular dynamics simulations, quantum-chemical methods, and classical microelectrostatic calculations. After validation against semiempirical Valence Bond/Hartree-Fock results, microelectrostatic calculations on a large number of electron-hole (e-h) pairs allowed a statistical study of charge separation energetics in realistic morphologies. Results show that charge separation is an energetically favorable process for about 50% of interfacial e-h pairs, which provides a rationale for the high internal quantum efficiencies reported for P3HT/PCBM heterojunctions. Three effects contribute to overcome the Coulomb attraction between electron and hole: (i) favorable electrostatic landscape across the interface, (ii) electronic polarization, and (iii) interface-induced torsional disorder in P3HT chains. Moreover, the energetic disorder due to the PCBM polar group is shown to play a key role in increasing the dissociation probability.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.