Pienia Żek Agnieszka, Dybała Filip, Polak Maciej P, Przypis Łukasz, Herman Artur P, Kopaczek Jan, Kudrawiec Robert
Department of Semiconductor Materials Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland.
Materials Science and Engineering Department, University of Wisconsin─Madison, Madison, Wisconsin 53706, United States.
J Phys Chem Lett. 2023 Jul 20;14(28):6470-6476. doi: 10.1021/acs.jpclett.3c01258. Epub 2023 Jul 12.
Recent scientific interest in examining the bandgap evolution of a MAPbI hybrid perovskite by applying hydrostatic pressure has mostly focused on a room-temperature tetragonal phase. In contrast, the pressure response of a low-temperature orthorhombic phase (OP) of MAPbI has not been explored and understood. In this research, we investigate for the first time how hydrostatic pressure alters the electronic landscape of the OP of MAPbI. Pressure studies using photoluminescence combined with calculations within density functional theory at zero temperature allowed us to identify the main physical factors affecting the bandgap evolution of the OP of MAPbI. The negative bandgap pressure coefficient was found to be strongly dependent on the temperature (α = -13.3 ± 0.1 meV/GPa, α = -29.8 ± 0.1 meV/GPa, and α = -36.3 ± 0.1 meV/GPa). Such dependence is related to the changes in the Pb-I bond length and geometry in the unit cell as the atomic configuration approaches the phase transition as well as the increasing phonon contribution to octahedral tilting as the temperature increases.
近期，通过施加静水压力来研究MAPbI混合钙钛矿的带隙演化这一科学兴趣主要集中在室温四方相上。相比之下，MAPbI低温正交相（OP）的压力响应尚未得到探索和理解。在本研究中，我们首次研究了静水压力如何改变MAPbI正交相的电子态势。利用光致发光进行的压力研究结合零温度下密度泛函理论的计算，使我们能够确定影响MAPbI正交相带隙演化的主要物理因素。发现负带隙压力系数强烈依赖于温度（α = -13.3 ± 0.1 meV/GPa，α = -29.8 ± 0.1 meV/GPa，以及α = -36.3 ± 0.1 meV/GPa）。这种依赖性与随着原子构型接近相变时晶胞中Pb - I键长和几何形状的变化有关，也与随着温度升高声子对八面体倾斜的贡献增加有关。
