Impact of organic-inorganic wavefunction delocalization on the electronic and optical properties of one-dimensional hybrid perovskites

Low-dimensional hybrid organic-inorganic perovskites have attracted a great deal of interest thanks to their high compositional and structural flexibilities that induce distinctive optoelectronic properties, for instance for light-emitting and photovoltaic applications. Here, we study at the density functional theory (DFT) level the electronic and optical properties of two one-dimensional hybrid perovskites incorporating cyanine or Victoria blue B (VBB) dye cations. Our electronic-structure analyses indicate that in both cases the highest occupied molecular orbitals of the cation dyes are nearly aligned with the band edges of the inorganic component; however, wavefunction delocalization between the two components only arises in the cyanine-perovskite system where electronic couplings can be identified, albeit weakly, between the organic dye cations and the inorganic framework. The excited-state properties of the cyanine-perovskite system were further evaluated by carrying out time-dependent DFT calculations on representative finite cluster models based on the bulk structures. The electronic couplings between the organic and inorganic components result in a small degree of charge-transfer contributions to the low-lying excited states, which in turn leads to a broadening of the lowest absorption band.

Automated summary

Low-dimensional hybrid organic-inorganic perovskites with high compositional and structural flexibilities have attracted significant attention for their distinct optoelectronic properties, such as in light-emitting and photovoltaic applications. In this study, we used density functional theory (DFT) to investigate the electronic and optical properties of two one-dimensional hybrid perovskites containing cyanine or Victoria blue B (VBB) dye cations. Our analyses demonstrated that the highest occupied molecular orbitals of the dye cations align closely with the band edges of the inorganic component, but wavefunction delocalization only occurs in the cyanine-perovskite system with weak electronic couplings between the organic and inorganic components. Time-dependent DFT calculations on finite cluster models revealed a small degree of charge-transfer contributions to the low-lying excited states in the cyanine-perovskite system, resulting in broadening of the lowest absorption band.