Spin-orbit effects on the electronic and optical properties of lead iodide

Lead iodide (PbI2) has gained much interest due to its direct electronic gap in the visible range and layered crystal structure. It has thereby been considered as a promising material for applications in atomically thin optoelectronic devices. In this work, we present a detailed investigation of the effect of spin-orbit coupling (SOC) that arises from the presence of heavy atoms on the electronic and optical properties of PbI2 using first-principles calculations based on density-functional theory and many-body perturbation theory. We find that SOC not only alters the bandgap but also induces the mixing of orbital characters, resulting in a significant change in the overall band structure and charge carrier effective masses. Moreover, the band orbital mixing caused by SOC results in the dramatic change in optical transition matrix elements and, correspondingly, the absorption spectrum. Our experimentally measured absorption spectra validate the calculation results and demonstrate the importance of SOC in the optical processes of PbI2. Our findings provide insights that are important for the potential use of PbI2 as a material platform for visible optoelectronic devices.

Automated summary

In this study, the influence of spin-orbit coupling on the electronic and optical properties of PbI2 was investigated using first-principles calculations. It was found that spin-orbit coupling not only altered the bandgap of PbI2 but also caused the mixing of orbital characters, resulting in changes in band structure and charge carrier effective masses. Additionally, spin-orbit coupling affected the optical transition matrix elements and absorption spectrum of PbI2. The experimental results supported the computational findings and highlighted the importance of spin-orbit coupling in the optical processes of PbI2.