Fluorinated spacers: an effective strategy to tailor the optoelectronic properties and stability of metal-halide perovskites for photovoltaic applications

Abstract

Metal halide perovskites or as simply known as perovskites are organic-inorganic hybrid materials that surpassed silicon-based photovoltaic (PV) technology in terms of power-conversion efficiency (PCE). However, low environmental stability remains...

Tuning charge carrier dynamics through spacer cation functionalization in layered halide perovskites: an ab initio quantum dynamics study

“…21,30,41,42 Due to similar steric parameters, the substitution of fluorine (van der Waals radii B 147 ps) with hydrogen (radii B 110 pm) in spacer cations maintains the overall crystal structure of LHPs without much geometric distortion. 43 The high electronegativity of fluorine can substantially modify the organic-inorganic sublattice coupling through C-FÁ Á ÁX (X is halogen), FÁ Á Áp, and hydrogen bonding interactions. [44][45][46] Furthermore, the large dipole moment in fluorinated spacer cations originates a high dielectric constant, reducing the associated confinement effects in LHPs.…”

Tuning Structure and Excitonic Properties of 2D Ruddlesden–Popper Germanium, Tin, and Lead Iodide Perovskites via Interplay between Cations

“…In quasi-2D Ruddlesden–Popper (RP) perovskites with the general formula (LA) 2 (A) n ‑1 B n X 3 n +1 , where X is a halide anion, A is a smaller A-site cation, and n indicates the perovskite layer thickness, the organic component (both LA and A cations) can be used to tune the perovskite structure. − Although the choice of spacer cation (LA) does not directly impact the electronic properties, it has significant impacts on the resulting inorganic orbital overlap, structural symmetry, stability and hydrophobicity, and dielectric screening of charge carriers. , Halogen substitution of the spacer cation is a versatile strategy for templating the 2D perovskite structure and manipulating the perovskite properties in different ways. Fluorinated spacer cations improve the stability of 2D perovskites. − Furthermore, H/F substitution can be used as a strategy to design ferroelectric perovskites by introducing a strong molecular dipole and increasing octahedral distortion . Halogenated spacer cations can additionally modulate the dielectric confinement of the 2D perovskite layers, which can lead to enhanced photophysical properties. − …”

Bandgap narrowing and piezochromism of doped two-dimensional hybrid perovskite nanocrystals under pressure

“…Two-dimensional (2D) hybrid perovskites are promising candidates for optoelectronic applications because of their unique electronic properties. [1][2][3][4][5][6][7] They differ significantly from traditional three-dimensional (3D) perovskites owing to their layered structures which give them structural diversity since the 2D counterparts are susceptible to external driving forces. Furthermore, doping other ions into perovskites can form an impurity energy level in the bandgap.…”