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

摘要

Methylammonium lead iodide (CH3NH3PbI3) perovskite solar cell has produced aremarkable breakthrough in the photovoltaic history of solar cell technologybecause of its outstanding device based performance as a light-harvestingsemiconductor. Whereas the experimental and theoretical studies of this systemin the solid state have been numerously reported in the last 4 years, itsfundamental cluster physics is yet to be exploited. To this end, this study hasperformed theoretical investigations using DFT-M06-2X/ADZP to examine theprincipal geometrical, electronic, topological, and orbital properties of theCH3NH3PbI3 nanocluster blocks. These clusters are found to be unusuallystrongly 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 theunderlying interactions as ultra-strong type. Based on this, together with theunusually high charge transfers, strong hyperconjugative interactions,sophisticated topologies of the charge density, and short intermoleculardistances uncovered, we have characterized the CH3NH3PbI3 as Mulliken innercomplexes. Additionally, the consequences of these, as well as of theultra-strong interactions, in designing novel functional nanomaterials arebriefly discussed. The various new results obtained in this study are not inperfect 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).