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The nature of hydrogen-bonding interaction in the prototypic hybrid halide perovskite, tetragonal CH3NH3PbI3.

Lee JH, Lee JH, Kong EH, Jang HM - Sci Rep (2016)

Bottom Line: Herein, we show that there exist two distinct types of the hydrogen-bonding interaction, naming α- and β-modes, in the tetragonal MAPbI3 on the basis of symmetry argument and density-functional theory calculations.The computed Kohn-Sham (K-S) energy difference between these two interaction modes is 45.14 meV per MA-site with the α-interaction mode being responsible for the stable hydrogen-bonding network.The computed bandgap (Eg) is also affected by the hydrogen-bonding mode, with Eg of the α-interaction mode (1.73 eV) being significantly narrower than that of the β-interaction mode (2.03 eV).

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, and Division of Advanced Materials Science (AMS), Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea.

ABSTRACT
In spite of the key role of hydrogen bonding in the structural stabilization of the prototypic hybrid halide perovskite, CH3NH3PbI3 (MAPbI3), little progress has been made in our in-depth understanding of the hydrogen-bonding interaction between the MA(+)-ion and the iodide ions in the PbI6-octahedron network. Herein, we show that there exist two distinct types of the hydrogen-bonding interaction, naming α- and β-modes, in the tetragonal MAPbI3 on the basis of symmetry argument and density-functional theory calculations. The computed Kohn-Sham (K-S) energy difference between these two interaction modes is 45.14 meV per MA-site with the α-interaction mode being responsible for the stable hydrogen-bonding network. The computed bandgap (Eg) is also affected by the hydrogen-bonding mode, with Eg of the α-interaction mode (1.73 eV) being significantly narrower than that of the β-interaction mode (2.03 eV). We have further estimated the individual bonding strength for the ten relevant hydrogen bonds having a bond critical point.

No MeSH data available.


The band structure and the partial density of states (PDOS) of the tetragonal MAPbI3 cell for the two distinct modes of the hydrogen-bonding interaction.(a) The band structure of the tetragonal MAPbI3 cell under the α-interaction mode (left) versus the band structure under the β-interaction mode (right). The ab initio band-structure calculations were performed along high-symmetry surface k-vectors of the first Brillouin zone. (b) The computed PDOS of the tetragonal MAPbI3 cell under the α-interaction mode (left) versus the PDOS under the β-interaction mode (right). The Pb 6pz-I 5p* orbital overlapping at the CBM is reasoned to be closely correlated with the bandgap reduction under the α-interaction mode.
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f5: The band structure and the partial density of states (PDOS) of the tetragonal MAPbI3 cell for the two distinct modes of the hydrogen-bonding interaction.(a) The band structure of the tetragonal MAPbI3 cell under the α-interaction mode (left) versus the band structure under the β-interaction mode (right). The ab initio band-structure calculations were performed along high-symmetry surface k-vectors of the first Brillouin zone. (b) The computed PDOS of the tetragonal MAPbI3 cell under the α-interaction mode (left) versus the PDOS under the β-interaction mode (right). The Pb 6pz-I 5p* orbital overlapping at the CBM is reasoned to be closely correlated with the bandgap reduction under the α-interaction mode.

Mentions: We have examined the effect of the hydrogen-bonding mode on the band structure of the tetragonal MAPbI3 cell. The computed band structures are similar to those previously reported by Mosconi et al.23. However, as indicated in Fig. 5a, the bandgap (Eg) at the zone-center Γ-point is significantly affected by the hydrogen-bonding mode. We have further examined the partial density-of-states (PDOS) to resolve the atomic-scale origin of this bonding-mode-dependent bandgap. As indicated in Fig. 5b, the conduction-band minimum (CBM) is characterized by the Pb 6p orbitals, which is irrespective of the hydrogen-bonding interaction mode. On other hand, the valence-band maximum (VBM) is featured by the Pb 6s and I 5p orbitals. A detailed analysis of the wavefunction-character indicates that the Pb 6p-I 5p* anti-bonding orbital corresponds to the overlapping at the CBM while the Pb 6s-I 5p* anti-bonding orbital represents the VBM. It is interesting to notice that in the case of the α-interaction mode, the PDOS of the Pb 6pz orbital at the CBM further penetrates into a lower energy region (down to 1.73 eV above the VBM; Fig. 5b). This lowers the CBM value with respect to the VBM, leading to the bandgap reduction in the case of the α-interaction mode.


The nature of hydrogen-bonding interaction in the prototypic hybrid halide perovskite, tetragonal CH3NH3PbI3.

Lee JH, Lee JH, Kong EH, Jang HM - Sci Rep (2016)

The band structure and the partial density of states (PDOS) of the tetragonal MAPbI3 cell for the two distinct modes of the hydrogen-bonding interaction.(a) The band structure of the tetragonal MAPbI3 cell under the α-interaction mode (left) versus the band structure under the β-interaction mode (right). The ab initio band-structure calculations were performed along high-symmetry surface k-vectors of the first Brillouin zone. (b) The computed PDOS of the tetragonal MAPbI3 cell under the α-interaction mode (left) versus the PDOS under the β-interaction mode (right). The Pb 6pz-I 5p* orbital overlapping at the CBM is reasoned to be closely correlated with the bandgap reduction under the α-interaction mode.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4759593&req=5

f5: The band structure and the partial density of states (PDOS) of the tetragonal MAPbI3 cell for the two distinct modes of the hydrogen-bonding interaction.(a) The band structure of the tetragonal MAPbI3 cell under the α-interaction mode (left) versus the band structure under the β-interaction mode (right). The ab initio band-structure calculations were performed along high-symmetry surface k-vectors of the first Brillouin zone. (b) The computed PDOS of the tetragonal MAPbI3 cell under the α-interaction mode (left) versus the PDOS under the β-interaction mode (right). The Pb 6pz-I 5p* orbital overlapping at the CBM is reasoned to be closely correlated with the bandgap reduction under the α-interaction mode.
Mentions: We have examined the effect of the hydrogen-bonding mode on the band structure of the tetragonal MAPbI3 cell. The computed band structures are similar to those previously reported by Mosconi et al.23. However, as indicated in Fig. 5a, the bandgap (Eg) at the zone-center Γ-point is significantly affected by the hydrogen-bonding mode. We have further examined the partial density-of-states (PDOS) to resolve the atomic-scale origin of this bonding-mode-dependent bandgap. As indicated in Fig. 5b, the conduction-band minimum (CBM) is characterized by the Pb 6p orbitals, which is irrespective of the hydrogen-bonding interaction mode. On other hand, the valence-band maximum (VBM) is featured by the Pb 6s and I 5p orbitals. A detailed analysis of the wavefunction-character indicates that the Pb 6p-I 5p* anti-bonding orbital corresponds to the overlapping at the CBM while the Pb 6s-I 5p* anti-bonding orbital represents the VBM. It is interesting to notice that in the case of the α-interaction mode, the PDOS of the Pb 6pz orbital at the CBM further penetrates into a lower energy region (down to 1.73 eV above the VBM; Fig. 5b). This lowers the CBM value with respect to the VBM, leading to the bandgap reduction in the case of the α-interaction mode.

Bottom Line: Herein, we show that there exist two distinct types of the hydrogen-bonding interaction, naming α- and β-modes, in the tetragonal MAPbI3 on the basis of symmetry argument and density-functional theory calculations.The computed Kohn-Sham (K-S) energy difference between these two interaction modes is 45.14 meV per MA-site with the α-interaction mode being responsible for the stable hydrogen-bonding network.The computed bandgap (Eg) is also affected by the hydrogen-bonding mode, with Eg of the α-interaction mode (1.73 eV) being significantly narrower than that of the β-interaction mode (2.03 eV).

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, and Division of Advanced Materials Science (AMS), Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea.

ABSTRACT
In spite of the key role of hydrogen bonding in the structural stabilization of the prototypic hybrid halide perovskite, CH3NH3PbI3 (MAPbI3), little progress has been made in our in-depth understanding of the hydrogen-bonding interaction between the MA(+)-ion and the iodide ions in the PbI6-octahedron network. Herein, we show that there exist two distinct types of the hydrogen-bonding interaction, naming α- and β-modes, in the tetragonal MAPbI3 on the basis of symmetry argument and density-functional theory calculations. The computed Kohn-Sham (K-S) energy difference between these two interaction modes is 45.14 meV per MA-site with the α-interaction mode being responsible for the stable hydrogen-bonding network. The computed bandgap (Eg) is also affected by the hydrogen-bonding mode, with Eg of the α-interaction mode (1.73 eV) being significantly narrower than that of the β-interaction mode (2.03 eV). We have further estimated the individual bonding strength for the ten relevant hydrogen bonds having a bond critical point.

No MeSH data available.