Impact of the interplay between the organic and inorganic sub-lattices in hybrid halide perovskites

Carlo Motta^a, Fedwa El Mellouhi^b, Sabre Kais^b, Nouar Tabet^b, Fahhad Alharbi^b, Stefano Sanvito^b

^aTrinity College Dublin and CRANN, Dublin

^bQatar Environment and Energy Research Institute,, P.O. Box 5825 Doha

International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics 2015 (HOPV15)

Roma, Italy, 2015 May 11th - 13th

Organizer: Filippo De Angelis

Poster, Carlo Motta, 051
Publication date: 5th February 2015

The hybrid halide perovskite CH₃NH₃PbI₃ has enabled solar cells to reach an efficiency close to 20% [1], demonstrating a pace for improvements with no precedents in the solar energy arena [2]. Despite such explosive progress, the microscopic origin behind the success of such material is still debated, with the role played by the organic cations in the light-harvesting process remaining unclear. In this work, density functional theory calculations reveal that the orientation of the organic molecules plays a fundamental role in determining the material electronic properties. Molecular reorientations induce distortions of the inorganic PbI₃ cage causing the electronic band edges to shift in reciprocal-space, an effect captured upon inclusion of dispersive forces in the description. As a consequence, inequivalent cation orientations, representing local energy minima, lead to bandstructures displaying either direct and indirect bandgaps [3]. Our observations are compatible with recent photoluminescence measurements. While this subtle effect weakly impacts the mobility of CH₃NH₃PbI₃ [4], it may be a concurrent cause of the slow carrier recombination and of the superior conversion efficiency of CH₃NH₃PbI₃. Our results will be discussed in relation to recent experiments of fast dynamics in this materials class.
Shift of the conduction band minimum from high symmetry point R (left) occurring upon rotation of the methylammonium in the inorganic lattice (right).
[1] Zhou, H. et al. Science 2014, 345, 542–546. [2] Grätzel, M. Nat. Materials 2014, 13, 838–842 [3] Motta, C.; El Mellouhi, F.; Kais, S.; Tabet, N.; Alharbi, F.; Sanvito, S. arXiv:1410.8365 [4] Motta, C.; El Mellouhi, F.; Sanvito, S. arXiv:1411.7904

nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.

MATSUS

Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.

International Conference on Hybrid and Organic Photovoltaics

International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.

Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics

The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.

International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics

The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.