A Nanocrystal Synthesis Derived Approach to Silver Bismuth Iodide Layered Double Perovskites with Aliphatic Amines: (CnH(2n+1)NH3)4AgBiI8

TL;DR

This paper presents a novel fast precipitation synthesis method for lead-free layered double perovskites with organic amines, achieving stable structures with tunable properties and potential applications in optoelectronics.

Contribution

It introduces a new nanocrystal-inspired synthesis route for stable, lead-free iodide layered double perovskites with specific organic amines, expanding the material's stability and tunability.

Findings

Successful synthesis of (CnH(2n+1)NH3)4AgBiI8 with n=10,12,14

Monoclinic crystal structure with edge-sharing octahedra

Band gap of approximately 2.1 eV, confirmed experimentally and theoretically

Abstract

Lead-free iodide double perovskites are an interesting class of materials since they combine a relatively low toxicity (compared to the lead counterpart) with the small bandgap typical of iodide-based perovskite structures. Their reported number is small due to their lower structural stability compared to the chloride and bromide analogues, hence their difficult synthesis. The structural constraints that limit stability, on the other hand, can be much relieved in layered, organic-inorganic perovskites. Following this line of thought, we report here a successful fast precipitation route to iodide layered (CnH(2n+1)NH3)4AgBiI8 (n = 10, 12, and 14) double perovskites that borrow concepts from the synthesis of colloidal nanocrystals. X-ray diffraction studies revealed for these compounds a monoclinic crystal structure containing edge-sharing alternated [AgI6] and [BiI6] octahedra. These materials have experimental band gaps of 2.1 eV, as also corroborated by theoretical calculations. We have also investigated their phase transitions by thermal analysis and temperature-dependent diffraction and found them to be similar to their lead-based layered perovskite counterparts.