Two-Dimensional Hybrid Perovskite as a Promising Semiconductor for Large Area Electronics

Speaker: Dr hab. Tomasz Marszałek (Max Planck Institute for Polymer Research (MPIP-MPG) Mainz Germany)

Abstract: The functionality of organic-inorganic perovskites in large area electronics depends on the quality of the molecular organization and thin film morphology. Therefore, control of nucleation and growth is important to reduce structural defects and domain boundaries in the perovskite film to ensure unhindered carrier transport and high device performance. Grain engineering controlled by film deposition parameters and the chemical structure of organic cations are novel approaches to improve charge carrier transport and understand the relationship between crystallization and ions migration. First, a hot casting method to effectively modulate grain size and grain boundary number to improve in-plane carrier transport in perovskite films is discussed. Based on the obtained results a close correlation between grain boundary density, carrier transport and ion migration will be presented. Secondly, a distinct odd-even effect in 2D Sn-based perovskite semiconductors is presented for the first time by incorporating phenylalkylammonium-based organic cations with different alkyl side chain lengths with odd and even carbon atoms. An odd-even oscillation of the charge carrier transport is revealed by optically pumped terahertz spectroscopy and transistor devices. Combining density functional theory calculations and simulated grazing-incidence wide-angle X-ray scattering, we show that the organic ligands with odd carbon atoms are featured with disordered crystal lattice and tilted inorganic octahedron leading to larger effective mass and thus inferior charge mobilities compared to the perovskites with an even carbon number of the organic cations.

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