Insights into the formation mechanism of two-dimensional lead halide nanostructures

TL;DR

This paper introduces a colloidal synthesis method for lead halide nanosheets, revealing their formation mechanism, structural evolution with temperature and time, and extending the approach to different halides, with potential applications in high-energy photon detection.

Contribution

It provides new insights into the chemical formation mechanism of lead halide nanosheets and demonstrates a versatile synthesis route for various lead halide nanostructures.

Findings

Crystals of PbI2 initially contain multiple polytypes.

Crystal structure transitions from polytypes to 2H with increased temperature or time.

Successful synthesis of lead bromide and chloride nanosheets.

Abstract

We present a colloidal synthesis strategy for lead halide nanosheets with a thickness of far below 100 nm. Due to the layered structure and the synthesis parameters the crystals of PbI2 are initially composed of many polytypes. We propose a mechanism which gives insight into the chemical process of the PbI2 formation. Further, we found that the crystal structure changes with increasing reaction temperature or by performing the synthesis for longer time periods changing for the final 2H structure. In addition, we demonstrate a route to prepare nanosheets of lead bromide as well as lead chloride in a similar way. Lead halides can be used as a detector material for high-energy photons including gamma and X-rays.