Improving Stability of Lead Halide Perovskite via PbF₂ Layer Covering

Abstract

The stability of perovskites is an urgent problem to be solved before commercialization. An ultrathin PbF2 layer covering the perovskite can be an effective strategy to improve the stability of the perovskite greatly. The perovskite/PbF2 interface (XPbI3/PbF2, X = Cs and MA) is constructed, and the structural and chemical properties are studied by first-principles calculations. The results show that PbF2 has better structural stability than the perovskites and can stabilize the octahedral frame of perovskite in the perovskite/PbF2 interface. The PbF2 layer reconstructs the XPbI3 surface, resulting in the perovskite PbI interface transforming into a more stable XI interface in the perovskite/PbF2 interface. Meanwhile, the tiny stress compression in the perovskite/PbF2 interface can enhance the stability of perovskite. The large affinity of F atoms can adsorb free Pb atoms and suppress deleterious ion migration. In addition, the XPbI3/PbF2 interfaces have good dynamic stability at room temperature (300 K). Therefore, the PbF2 layer covering provides new ideas for the stability study of perovskites.

Simultaneous Enhanced Efficiency and Stability of Perovskite Solar Cells Using Adhesive Fluorinated Polymer Interfacial Material

“…Figure b (for Model 1) and Figure S3 (for the other models) show the difference in electron density between the PFPT3–perovskite interfacial system and the superimposed densities of PFPT3 fragments and perovskite. The electropositive Pb atom of the perovskite forms a surface bond with the electronegative F atom of PFPT3, where a partial electron transfer occurs from Pb to F, which corroborates the XPS results. A partial density of states (PDOS) analysis further supports Pb–F bond formation, as indicated by the broadened F-states near the Fermi level (Figure S4).…”

Exploring the Coexistence Mechanism of CsPb2Br5 and CsPbBr3 Based on the Competitive Phase Diagram

“…Although electrons and holes do not recombine in the CsPb 2 Br 5, theCsPb 2 Br 5 acts as a protective layer, because the CsPb 2 Br 5 is stable under high temperature, high pressure, and high humidity. − However, the stability of 3D perovskites is a problem for researchers. Previous studies reported that other materials like 2D perovskites, PF 2 , and so on are beneficial to improve the stability of 3D perovskites. − The CsPb 2 Br 5 and the CsPbBr 3 have the same elemental composition, which can also inhibit the surface defects of CsPbBr 3 , such as V Br .…”

Revealing the Potential Crystal Structures of Earth-Abundant Nontoxic Photovoltaic CuBiI4

“…Their CBM mainly attributes to the Bi-6 p and I-5 p orbitals. Bader and electron localization function analyses (Figure S3 and Table S4) show an electronic structure intermediate between fully ionic and fully covalent bonding, similar in the character to the metal halide bonding in MAPbI 3 …”

“…The main features of the three structures are the co-existence of Cu−I, Bi−I bonds, and S4) show an electronic structure intermediate between fully ionic and fully covalent bonding, similar in the character to the metal halide bonding in MAPbI 3 . 38 The electronic band structures of the three polymorphs are presented in Figure 3, and the band gaps (E g ) calculated by the HSE06 method are presented in Table S4. The results show that P1̅ − III and P2 1 /m are indirect gap semiconductors with E g = 1.4 and 1.9 eV, respectively, while P1̅ − II is a direct gap semiconductor with E g = 2.0 eV.…”