Substitution induced band structure shape tuning in hybrid perovskites (CH₃NH₃Pb_1−xSn_xI₃) for efficient solar cell applications

Abstract

Electronic and optical properties of CH3NH3Pb1−xSnxI3 are determined using DFT. Sn doping narrows band gap allowing 850 nm absorption. Delocalized Sn-5p induced electronic states increase mobility. 50% Sn doping is revealed as optimum composition.

Halogen in materials design: Fluoroammonium lead triiodide (FNH3PbI3) perovskite as a newly discovered dynamical bandgap semiconductor in 3D

“…These can be either all‐inorganic, or a mixture of an organic moiety with an inorganic one (organic–inorganic), or metal‐organic hybrids . A critical aspect of some of these perovskites lies in the “direct‐to‐indirect/indirect‐to‐direct” nature of their bandgap . The view is not very surprising since this kind of bandgap transition has shown to have a significant impact on fast/slow recombination, as well as that on the extent of power conversion efficiency .…”

“…In addition, the electronic density of states (DOS) spectra are examined to provide insight into the nature of various orbital characters that have participated to build the valence and conduction bands of FNH 3 PbI 3 . An important property called carrier mass is also examined to show whether the effective mass of the electrons is competitive with that of the holes for the material, an attribute that might be useful to infer the ambipolar nature of the charge transport . The standard relationship, , often invoked in solid state semiconductor physics was used to evaluate the effective masses of the charge carriers, where m* is the effective mass of the charge carrier (hole/electron), k is the wavenumber, and is the valence/conduction band energy in k ‐space given by: .…”

“…[4,5,7] A critical aspect of some of these perovskites lies in the "direct-to-indirect/indirect-to-direct" nature of their bandgap. [30][31][32][33][34] The view is not very surprising since this kind of bandgap transition has shown to have a significant impact on fast/slow recombination, as well as that on the extent of power conversion efficiency. [35,36] This attribute has explained the extremely long charge-carrier lifetimes and high open-circuit voltages observed for the thin films of CH 3 NH 3 PbI 3 .…”

The Emergence of the Mixed Perovskites and Their Applications as Solar Cells

“…Chen et al [117] employed DFT calculations to elucidate the electronic and optical properties of MAPb 1−x Sn x I 3 (x = 0, 0.25, 0.5, 0.75, 1.0) PVSK. They found that substituting Pb with Sn may change the position of the valence band maximum and narrow the band gap, leading to light absorption up to 850 nm.…”

Characterization of optically active perovskite electrodes

“…Through the gradual Sn(II)-Pb(II) exchange in MAPb1−xSnxI3 continuous variation of the optoelectronic properties was achieved (Eg = 1.17 -1.55 eV). [69][70][71] Interestingly, this exchange shows deviation from Vegard's law. Namely, the bandgap of the solid solutions is not a linear function of composition (lattice parameter).…”