Structural and electronic features of Si/CH3NH3PbI3 interfaces with optoelectronic applicability: Insights from first-principles. (January 2020)

• Record Type: Journal Article
• Authors: Giorgi, Giacomo
• Is Part Of: Nano energy. Volume 67(2020)
• Publication Date: 2020-01
• Subjects: Density functional theory -- Hybrid organic-inorganic halide perovskites -- Heterostructures -- Band offset -- Tandem cells -- Electronic properties & strain; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2019.104166
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Motivated by the complete lack of theoretical knowledge in view of their applications in solar device processing and in optoelectronics, I have here investigated the structural and the electronic properties of interfaces constituted by the most relevant technological surface of silicon, i.e. the (001), and methylammonium (MA) lead iodide (001)-oriented surfaces. Results show a thermodynamic enhanced stability in the case of the lead iodide (PbI2 -) terminated CH3 NH3 PbI3 /Si interface, while the other investigated termination, the MAI-rich one, shows a better alignment between bandedges once interfaced with Si. Indeed, while for the latter a clear type-II heterojunction is observed, the former still shows a type-II behavior where anyway conduction band minima of Si and CH3 NH3 PbI3 are (almost) degenerate. The DOS show the raise of p -like states in the gap close to the valence band due to the strain present at the Si-Si and at the equatorial Pb-I bonds in the PbI2 -terminated/Si interface and indicate the unsuitability of this interface for optoelectronic applications. The present work reveals how the chemistry of the interface, i.e. the different bonding arrangement between silicon and CH3 NH3 PbI3, induces completely different carrier transport properties along the heterostructure with potentially detrimental effects in the final device. To date, this work is the first theoretical modellization of the interface between these two semiconductors and provides important information in the processes involved in 2-terminal tandem device assembling and in all the processes of perovskite growth on silicon substrate. Graphical abstract: Details of the wavefunction distribution of the Valence Band maximum of the Si/CH3 NH3 PbI3 (MAI-terminated) interface. Image 1 Highlights: Realistic silicon/CH3 NH3 PbI3 stress-free interfaces are here assembled and optimized by means of a first-principles parameter-free approach for the very first time. Both terminations, i.e. PbI2- and CH3 NH3 I-, are considered in the interface formation with Si (001) surface. Strain at the interface is found to play a fundamental role in the final optoelectronic applicability of such nanohybrids. Si/CH3 NH3 PbI3 (CH3 NH3 I-terminated) interfaces have a clear type-II heterojunction behavior but are less thermodynamically favored. Si/CH3 NH3 PbI3 (PbI2- terminated) interfaces show a worse bandoffset alignment for optoelectronic applications (regardless their more favorable formation).