With a thickness of only a few nanometers and superior optical performance, a research group led by Professor Wang Lin from Nanjing University of Technology developed an ultra-thin two-dimensional lead iodide crystal, and regulate the optical properties of two-dimensional transition metal sulfide materials with the crystal.

This scientific achievements provide a new idea for the manufacturing of solar cells and photodetectors. The results were published in the latest issue of the international journal Advanced Materials.

"This ultra-thin lead iodide nanosheet, which we first prepared, is termed as 'Atomic Thickness Wide Band Gap Two-Dimensional PbI2 Crystal', an ultra-thin semiconductor material with a thickness of only a few nanometers."

Sun Yan, the first author and Ph.D. student at Nanjing University of Technology, said that they used a solution method to synthesize. This method has low requirements on equipment, and has the advantages of simplicity, fast speed, and high efficiency. It also can meet the requirements of large-area and high-volume material preparation.

The synthesized lead iodide nanosheets have a regular triangular or hexagonal shape with an average size of 6 micrometers, a smooth surface and good optical properties.

Researchers have combined this ultra-thin lead iodide nanosheet with two-dimensional transition metal sulfides that are artificially designed. These materials are stacked together to obtain different types of heterojunctions.

Because the energy levels are arranged differently, iodine Lead can have different effects on the optical performance of different two-dimensional transition metal sulfides.

The energy band structure can effectively improve the luminous efficiency, and is advantageous for fabricating devices such as light-emitting diodes and lasers, which are used in display and illumination, and can be utilized in the fields of photodetectors and photovoltaic devices.

This achievement realizes the control of the optical properties of two-dimensional transition metal sulfide materials by ultra-thin lead iodide.

Compared with traditional silicon-based materials, the new material have flexibility and micro-nano characteristics, so they can be applied to In the preparation of flexible and integrated optoelectronic devices.

The two-dimensional semiconductor heterojunction based on lead iodide nanosheets also has broad application prospects in the field of integrated micro-nano-optical devices, and provides a new idea for the manufacture of solar cells and photodetectors, etc.