Wierzbowska Małgorzata, Meléndez Juan José
Institute of High Pressure Physics, Polish Academy of Sciences, Sokołowska 29/37, 01-142, Warsaw, Poland.
Department of Physics, University of Extremadura, Avenida de Elvas, s/n, 06006, Badajoz, Spain.
Phys Chem Chem Phys. 2023 Jan 18;25(3):2468-2476. doi: 10.1039/d2cp04288f.
We theoretically investigate lead iodide perovskites of general formula APbI for a series of metallic cations (namely Cs, Rb, K, Na and Li) by means of density functional theory, the GW method and the Bethe-Salpeter equation including spin-orbit coupling. We demonstrate that the low-energy edges (up to 1.3 eV) of the absorption spectra are dominated by weakly bound excitons, with binding energies of ∼ 30-80 meV, and the corresponding intensities increase as metallic cations become lighter. The middle parts of the spectra (1.8-2.4 eV), on the other hand, contain optical dipole transitions comprising more confined excitons ( ∼ 150-200 meV) located at PbI. These parts of the spectra correspond to the optical-gain wavelengths which are experimentally achieved in optically pumped perovskite lasers. Finally, the higher energy parts, from about 2.8 eV (LiPbI) to 4.3 eV (CsPbI), contain optical transitions with very confined excitons ( ∼ 220-290 meV) located at halide atoms and the empty states of the metallic cations.
我们通过密度泛函理论、GW方法以及包含自旋轨道耦合的贝叶斯-萨尔皮特方程，从理论上研究了一系列金属阳离子（即铯、铷、钾、钠和锂）的通式为APbI的碘化铅钙钛矿。我们证明，吸收光谱的低能边缘（高达1.3电子伏特）由弱束缚激子主导，其束缚能约为30 - 80毫电子伏特，并且随着金属阳离子变轻，相应的强度增加。另一方面，光谱的中间部分（1.8 - 2.4电子伏特）包含光学偶极跃迁，其中包括位于PbI处的更局域化的激子（约150 - 200毫电子伏特）。光谱的这些部分对应于在光泵浦钙钛矿激光器中通过实验实现的光学增益波长。最后，从约2.8电子伏特（LiPbI）到4.3电子伏特（CsPbI）的较高能量部分，包含位于卤化物原子处以及金属阳离子空态的具有非常局域化激子（约220 - 290毫电子伏特）的光学跃迁。
