Chiroptical Spectroscopy and Nonadiabatic Dynamics of Excitons in Nanostructured Lead-Halide Perovskite

Organic-inorganic lead-halide perovskite materials have shown to be an interesting ‘play-ground’ for controlling the structure to exhibit unique photo-physics. Primarily, the choice of organic ligand can (i) control the structure of the inorganic phase and (ii) be designed to promote charge-transfer between the organic-inorganic layers. These unique properties can then be directed to do useful photo-chemistry, such as catalysis. Here we use first-principles methods to model the change in photo-physical response of lead-halide perovskite by changing the organic ligand. First investigate the emergence of chiroptical response of lead-halide perovskite models due to their interaction with chiral organic molecules¹. Structure-to-property relationships resulting in the strong circular dichroism will be discussed^2,3. Second, we investigate the role of organic spacer ligands on the exciton binding energies.⁴ We find that ligands containing large -conjugation groups, such as naphthalene, can introduce a type-II band alignment with the inorganic lead-halide layer. This alignment introduces charge-transfer character and significantly reduces binding energies which can promote the generation of free-charge carriers. We then implement non-adiabatic dynamics using the fewest-switches surface-hopping algorithm incorporating many-body excitonic effects into the non-adiabatic couplings, going beyond the independent orbital approximation.⁵ We find that without decoherence corrections the predicted recombination rate accelerates when including many-body effects into the couplings, whereas when including decoherence the rates are within 10% of each other. This indicates that approximations for the decoherence corrections are more dominate than the approximation for the electronic-basis to compute the non-adiabatic couplings when computing non-radiative recombination lifetimes.

¹Forde, A., Tretiak, S., Neukirch, A. J. J. Phys. Chem. Lett. 2022, 13, 2, 686–693

²Forde, A., Tretiak, S., Neukirch, A. Nano Lett. 2024, 24, 30, 9276–9282

³Forde, A., Tretiak, S., Neukirch, A J. Mater. Chem. C, 2023, 11, 12374-12383

⁴Forde, A., Tretiak, S. Neukirch, A. J.,; Nano Lett. 2023, 23, 24, 11586–11592

⁵Forde, A., Neukirch, A. J., Tretiak, S.; J. Phys. Chem. Lett. (In review)