Organic-Inorganic Hybrid CH3NH3PbI3 Perovskite Solar Cell Nanoclusters: Revealing Ultra-Strong Hydrogen Bonding and Mulliken Inner Complexes and Their Implication in Materials Design

TL;DR

This study uses advanced computational methods to analyze CH3NH3PbI3 nanoclusters, revealing ultra-strong hydrogen bonds and Mulliken inner complexes, which have implications for designing new nanomaterials.

Contribution

It provides the first detailed theoretical analysis of the fundamental cluster physics of CH3NH3PbI3, highlighting ultra-strong interactions and complex charge transfer phenomena.

Findings

Clusters are strongly bound with energies between 93.53 and 125.11 kcal/mol.

Identified ultra-strong hydrogen bonds and Mulliken inner complexes.

Implications for designing novel functional nanomaterials.

Abstract

Methylammonium lead iodide (CH3NH3PbI3) perovskite solar cell has produced a remarkable breakthrough in the photovoltaic history of solar cell technology because of its outstanding device based performance as a light-harvesting semiconductor. Whereas the experimental and theoretical studies of this system in the solid state have been numerously reported in the last 4 years, its fundamental cluster physics is yet to be exploited. To this end, this study has performed theoretical investigations using DFT-M06-2X/ADZP to examine the principal geometrical, electronic, topological, and orbital properties of the CH3NH3PbI3 nanocluster blocks. These clusters are found to be unusually strongly bound, with binding energies lying between 93.53 and 125.11 kcal mol-1 (beyond the covalent limit, 40 kcal mol-1), enabling us to characterize the underlying interactions as ultra-strong type. Based on this, together with the unusually high charge transfers, strong hyperconjugative interactions, sophisticated topologies of the charge density, and short intermolecular distances uncovered, we have characterized the CH3NH3PbI3 as Mulliken inner complexes. Additionally, the consequences of these, as well as of the ultra-strong interactions, in designing novel functional nanomaterials are briefly discussed. The various new results obtained in this study are not in perfect agreement with those already reported experimentally (Nat. Commun. 2015, 6, 7124), and computationally (Chem. Commun., 2015, 51, 6434; Sci. Rep. 2016, doi:10.1038/srep21687; Chem. Mater. 2016, 28, 4259; J. Mat. Chem A 2016, 4, 4728; J. Phys. Chem. Lett. 2016, 7, 1596).