In this paper, we study the organometal lead halides (OLH) based perovskite solar cells (PSC). In fact, we investigate and discuss the electronic properties of the novel solar perovskites CsMBr3 (M = Pb or Ge) materials, using the DFT method combined with the Quantum Espresso package. Moreover, the effect of the lattice parameter and the number of layers on the band gap value of the solar perovskites photovoltaic CsMBr3 (M = Pb or Ge) have been improved.

Indeed, we inspect the structural properties of the studied materials and found that the optimized lattice parameter is equal to 6.0 Å for the solar perovskite material CsPbBr3. While, for the solar material CsGeBr3, the optimized lattice parameter value is 5.7 Å. In addition, it is found that the band gap value increases for increasing the lattice parameter values for the two materials.

On the other hand, when increasing the number of layers of the solar perovskites CsMBr3 (M = Pb or Ge), the total energy decreases. Furthermore, the band gap crosses through a maximum before decreasing more and more for sufficiently large number of layers.

在本文中，我们研究了基于有机金属卤化铅（OLH）的钙钛矿太阳能电池（PSC）。事实上，我们使用 DFT 方法结合 Quantum Espresso 包装来研究和讨论新型太阳能钙钛矿 CsMBr3（M = Pb 或 Ge）材料的电子特性。此外，晶格参数和层数对太阳能钙钛矿光伏 CsMBr3（M = Pb 或 Ge）带隙值的影响得到了改善。

事实上，我们检查了所研究材料的结构特性，发现太阳能钙钛矿材料 CsPbBr3 的优化晶格参数等于 6.0 Å。而对于太阳能材料 CsGeBr3，优化的晶格参数值为 5.7 Å。此外，发现随着两种材料的晶格参数值的增加，带隙值增加。

另一方面，当增加太阳能钙钛矿 CsMBr3（M = Pb 或 Ge）的层数时，总能量降低。此外，对于足够多的层，带隙在逐渐减小之前穿过最大值。