Influence of halide precursor type and its composition on the electronic properties of vacuum deposited perovskite films

Abstract

We fabricate mixed halide perovskite films through dual-source vacuum deposition of PbX2 (X = Cl, Br, and I) and methyl ammonium iodide (MAI) precursors with various deposition ratios. Vacuum deposition is an optimal way for film fabrication because it gives a uniform perovskite film which is free from contamination such as metallic phase lead, residual solvent, and moisture. The ionization potential and bandgap of MAPb(I1-yBry)3 film are controlled by changing the halide composition and lattice constant. In contrast, MAPb(I1-yCly)3 film shows negligible difference from MAPbI3 in terms of structural and electronic properties, which is due to poor Cl incorporation in the film from the MACl removal during crystal formation. An excess supply of MAI is necessary to form a perovskite crystal structure. Based on the elemental stoichiometry analysis, the additional methyl ammonium cation with respect to Pb in the film plays a critical role in changing the electron affinity and energy level alignment.

Imprinting Chirality onto the Electronic States of Colloidal Perovskite Nanoplatelets

“…The red peak at 402.3 eV is characteristic of nitrogen in a perovskite material, and the blue peak at 400.3 eV is consistent with unbound amine ligands . The Pb and Br spectra each exhibit a prominent doublet (red), in agreement with previous studies of perovskites: the Pb 4f 7/2 and Pb 4f 5/2 doublet is at 138.9 and 143.8 eV, and the Br 3d 5/2 and Br 3d 3/2 doublet is at 68.6 and 69.5 eV . The additional lead doublet at 136.7 and 141.7 eV (blue) is consistent with the binding energy for metallic Pb and validates the assignment of the quasiparticles in the TEM to metallic Pb.…”

Quantum Dots of [Na4Cs6PbBr4]8+, Water Stable in Zeolite X, Luminesce Sharply in the Green

“…[ 28 ] Several XPS peaks are shown in high resolution in Figure S1 (Supporting Information). When the Pb 2+ 4f binding energies in Pb,Br,H,Cs,Na−X, CsPbBr 3 , and PbBr 2 are compared, it can be seen that those of Pb 4f 5/2 and 4f 7/2 increase sequentially in the order Pb,Br,H,Cs,Na−X (142.7 and 137.9 eV), CsPbBr 3 (average values of several, 143.3 and 138.4 eV) [ 7e,29 ] , and PbBr 2 (143.9 and 139.05 eV) [ 30 ] (Figure 7d). This indicates that the interaction between the nucleus and an electron in the Pb 2+ 4f orbital is weakened as the number of Br − ions that “belong” to each Pb 2+ ion increases (A more detailed discussion of the Br − ion count is in the Supporting Information).…”

Lead‐Free Organic–Inorganic Hybrid Perovskites for Photovoltaic Applications: Recent Advances and Perspectives

“…As the core unit to realize high performance, organic–inorganic hybrid perovskite materials have a structure of ABX 3 (A: CH 3 NH 3 + , CH(NH 2 ) 2 + , Cs + , B: Pb 2+ , Sn 2+ ; X: Cl – , Br – or I – ), where the A cation resides at the eight corners of the cubic unit while the B cation is located at the center of the body of an octahedral [BX 6 ] 4− cluster . In the typical ABX 3 structure, A, B, and X ions must correspond to the tolerance factor t where R A , R B , and R X are the ionic radii for the A, B, and X position, respectively.…”