Structural Evolution of Perovskites by Amine Configuration

Mandal, Sitavro (2023) Structural Evolution of Perovskites by Amine Configuration. Masters thesis, Indian Institute of Science, Education and Research Kolkata.

Text (MS dissertation of Sitavro Mandal (18MS027)) Thesis_18MS027.pdf - Submitted Version Restricted to Repository staff only Download (2MB)

Abstract

Metal-halide perovskites are an encouraging class of materials in the field of photovoltaics and optoelectronics. These types of perovskites provide an ample opportunity to expand the number of metals and their various oxidation states. In the recent years, it has been possible to generate hybrid layered perovskites (HLDPs) by the dimensional reduction of halide perovskites. HLDPs are the two-dimensional (2D) derivatives of 3D double perovskites (Cs₂M(I)M(III)X₆, X= Br, Cl-, I-) in which inorganic layers consisting of alternate octahedra of M(I) and M(III) are separated by single (Dion-Jacobson, DJ) or double (Ruddlesden-Popper, RP) layers of organic spacers. This type of dimensional reduction in halide perovskites pave a way for generating the properties desirable in optoelectronics through the quantum confinement effects. A series of DJ silver and bismuth based perovskites with even number of amines in the organic spacers are widely reported. Reports of silver and bismuth based HLDPs with odd amines as organic spacers are less known. Keeping this in mind, two silver and bismuth based HLDPs (1,3 PPDA)yAgBiBrx(P-13) and 1,5 PDA)yAgBiBrx(P-15) are synthesised with 1,3 propanediamine (1,3 PPDA) and 1,5 pentanediamine (1,5 PDA) as organic spacers. P-13 is formed as a DJ-type HLDP structure with structural formula (1,3 PPDA)₂AgBiBr₈. P-15 exists as a 1D structure having only bismuth octahedra with structural formula (1,5PDA)BiBr₅. A dimensional reduction is thus clearly observed from Cs₂AgBiBr₆ (3D) to P-13 (2D) to P-15 (1D) with the change in organic spacers, respectively. This is also clearly evident in the increase of blue shift of the absorption edge and emission maxima and increase of band gaps from Cs2AgBiBr6 to P-13 to P-15. The trend of increase of trap density and decrease of charge carrier mobility also matches with the octahedral distortions observed in these compounds. These low-dimensional materials show excellent stability up to higher temperatures (300℃) and can be used in optoelectronics in the future.

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