Synthesis, Crystal Structure and Properties of a Perovskite-Related Bismuth Phase, (NH4)3Bi2I9

TL;DR

This paper reports the synthesis, crystal structure, and properties of a lead-free layered perovskite-like material, (NH4)3Bi2I9, highlighting its potential as a stable, environmentally friendly alternative for photovoltaic applications.

Contribution

The study introduces a new bismuth-based perovskite-like compound, providing structural data, electronic properties, and conductivity measurements relevant for solar cell use.

Findings

Band gap around 2.04 eV, lower than CH3NH3PbBr3

Structural analysis confirms layered perovskite architecture

Potential application as lead-free photovoltaic material

Abstract

Organic-inorganic halide perovskites, especially methylammonium lead halide, have recently led to a remarkable breakthrough in photovoltaic devices. However, due to the environmental and stability concerns of the heavy metal, lead, in these perovskite based solar cells, research in the non-lead perovskite structures have been attracting increasing attention. In this study, a layered perovskite-like architecture, (NH4)3Bi2I9, was prepared in solution and the structure was solved by single crystal X-ray diffraction. The results from DFT calculations showed the significant lone pair effect of the bismuth ion and the band gap was measured as around 2.04 eV, which is lower than the band gap of CH3NH3PbBr3. Conductivity measurement was also performed to examine the potential in the applications as an alternative to the lead containing perovskites.