Doping of metal-free molecular perovskite with hexamethylenetetramine to create non-centrosymmetric defects

Abstract

The metal-free perovskite (dabcoH22+)(NH4)Br (d-Br) (dabco: 1,4-diazabicyclo[2.2.2]octane) was doped with non-centrosymmetric hexamethylenetetramine.

Molecular Ferroelectrics‐Driven High‐Performance Perovskite Solar Cells

“…Ionic diffusion and partial ionic substitution might occur at several molecule layer levels between HMFE and perovskite.I th as been reported that al ittle bit of doping can change macroscopic behaviors. [21] This strong PL suggests that HMFE with unique chemical structure ( Figure S1) can effectively passivate the parasitic defects from perovskite through cation exchange and filling of iodide vacancies,w hich matches well with previous reports. [15,22] Time-resolved PL measurements also support the PL results (Figure 3b).…”

Molecular Ferroelectrics‐Driven High‐Performance Perovskite Solar Cells

“…Ionic diffusion and partial ionic substitution might occur at several molecule layer levels between HMFE and perovskite. It has been reported that a little bit of doping can change macroscopic behaviors [21] . This strong PL suggests that HMFE with unique chemical structure (Figure S1) can effectively passivate the parasitic defects from perovskite through cation exchange and filling of iodide vacancies, which matches well with previous reports [15, 22] .…”

Molecular solid solutions for advanced materials – homeomorphic or heteromorphic

“…B-Site is NH 4 + , H 3 O + , or alkali metal ion, and X site is a halide and molecular ions such as BF 4 − . [77][78][79][80][81][82][83][84][85] The size evolutions from inorganic perovskite to molecular perovskite via organic-inorganic perovskite are summarised in Table 1. B-Site ions of the molecular perovskite are more friendly to both human health and the earth environment.…”

“…84 Recently, we reported a solid solution for the metal-free molecular perovskite by mixing the A-site cations with centrosymmetric dabco and non-centrosymmetric hmta. 85 Both molecules are doubly protonated on N atoms, having molecules with D 3h (dabcoH 2 2+ ) and C 2v (hmtaH 2 2+ ) symmetry. Both cation form a perovskite-type structure (dabcoH 2 )(NH 4 )Br 3 (d-Br) 78 and (hmtaH 2 )(NH 4 )Br 3 (h-Br) (Fig.…”

“…These two structural defects cause lattice distortions in (d,h)-Br. 85 The symmetry of the A-site molecule templates is that of BX 6 octahedron. Thus miscibility was low even though molecular volume and crystallographic lattice dimensions are similar in d-Br and h-Br.…”