Characterization of highly crystalline lead iodide nanosheets prepared by room-temperature solution processing

TL;DR

This paper presents a simple solution-based method to synthesize highly crystalline ultrathin lead iodide nanosheets, thoroughly characterizes their properties, compares experimental results with theoretical calculations, and demonstrates their application in photodetectors.

Contribution

It introduces an easy synthesis technique for ultrathin PbI2 nanosheets and provides comprehensive experimental and theoretical characterization of these 2D materials.

Findings

Successful synthesis of ultrathin, highly crystalline PbI2 nanosheets

Detailed optical, Raman, and electron microscopy characterization

Demonstration of PbI2-based photodetectors with studied optoelectronic properties

Abstract

Two-dimensional semiconducting materials are particularly appealing for many applications. Although theory predicts a large number of two-dimensional materials, experimentally only a few of these materials have been identified and characterized comprehensively in the ultrathin limit. Lead iodide, which belongs to the transition metal halides family and has a direct bandgap in the visible spectrum, has been known for a long time and has been well characterized in its bulk form. Nevertheless, studies of this material in the nanometer thickness regime are rather scarce. In this article we demonstrate an easy way to synthesize ultrathin, highly crystalline flakes of PbI2 by precipitation from a solution in water. We thoroughly characterize the produced thin flakes with different techniques ranging from optical and Raman spectros-copy to temperature-dependent photoluminescence and electron microscopy. We compare the results to ab initio calculations of the band structure of the material. Finally, we fabricate photodetectors based on PbI2 and study their optoelectronic properties.