Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
Univ. of Cambridge (United Kingdom). Cavendish Lab.
Boston Univ., MA (United States)
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Kavli Energy NanoScience Institute, Berkeley, CA (United States)
The spatial extent of excitons in molecular systems underpins their photophysics and utility for optoelectronic applications. Phonons are reported to lead to both exciton localization and delocalization. However, a microscopic understanding of phonon-induced (de)localization is lacking, in particular, how localized states form, the role of specific vibrations, and the relative importance of quantum and thermal nuclear fluctuations. Here, we present a first-principles study of these phenomena in solid pentacene, a prototypical molecular crystal, capturing the formation of bound excitons, exciton-phonon coupling to all orders, and phonon anharmonicity, using density functional theory, the ab initio GW-Bethe-Salpeter equation approach, finite-difference, and path integral techniques. In this study, we find that for pentacene zero-point nuclear motion causes uniformly strong localization, with thermal motion providing additional localization only for Wannier-Mott-like excitons. Anharmonic effects drive temperature-dependent localization, and, while such effects prevent the emergence of highly delocalized excitons, we explore the conditions under which these might be realized
Alvertis, Antonios M., et al. "Phonon-Induced Localization of Excitons in Molecular Crystals from First Principles." Physical Review Letters, vol. 130, no. 8, Feb. 2023. https://doi.org/10.1103/physrevlett.130.086401
Alvertis, Antonios M., Haber, Jonah B., Engel, Edgar A., Sharifzadeh, Sahar, & Neaton, Jeffrey B. (2023). Phonon-Induced Localization of Excitons in Molecular Crystals from First Principles. Physical Review Letters, 130(8). https://doi.org/10.1103/physrevlett.130.086401
Alvertis, Antonios M., Haber, Jonah B., Engel, Edgar A., et al., "Phonon-Induced Localization of Excitons in Molecular Crystals from First Principles," Physical Review Letters 130, no. 8 (2023), https://doi.org/10.1103/physrevlett.130.086401
@article{osti_2293519,
author = {Alvertis, Antonios M. and Haber, Jonah B. and Engel, Edgar A. and Sharifzadeh, Sahar and Neaton, Jeffrey B.},
title = {Phonon-Induced Localization of Excitons in Molecular Crystals from First Principles},
annote = {The spatial extent of excitons in molecular systems underpins their photophysics and utility for optoelectronic applications. Phonons are reported to lead to both exciton localization and delocalization. However, a microscopic understanding of phonon-induced (de)localization is lacking, in particular, how localized states form, the role of specific vibrations, and the relative importance of quantum and thermal nuclear fluctuations. Here, we present a first-principles study of these phenomena in solid pentacene, a prototypical molecular crystal, capturing the formation of bound excitons, exciton-phonon coupling to all orders, and phonon anharmonicity, using density functional theory, the ab initio GW-Bethe-Salpeter equation approach, finite-difference, and path integral techniques. In this study, we find that for pentacene zero-point nuclear motion causes uniformly strong localization, with thermal motion providing additional localization only for Wannier-Mott-like excitons. Anharmonic effects drive temperature-dependent localization, and, while such effects prevent the emergence of highly delocalized excitons, we explore the conditions under which these might be realized},
doi = {10.1103/physrevlett.130.086401},
url = {https://www.osti.gov/biblio/2293519},
journal = {Physical Review Letters},
issn = {ISSN 0031-9007},
number = {8},
volume = {130},
place = {United States},
publisher = {American Physical Society (APS)},
year = {2023},
month = {02}}