Naphthalenediimide/Formamidinium-Based Low-Dimensional Perovskites

Abstract

Low-dimensional hybrid perovskites have emerged as promising materials for optoelectronic applications. Although these materials have already demonstrated enhanced stability as compared to their three-dimensional perovskite analogues, their functionality has been limited by the insulating character of the organic moieties that primarily play a structure-directing role. This is particularly the case for the layered (2D) perovskite materials based on formamidinium lead iodide (FAPbI3) that remain scarce. We demonstrate a low-dimensional hybrid perovskite material based on a SPbI4 composition incorporating an electroactive naphthalenediimide (NDI) moiety as an organic spacer (S) between the perovskite slabs and evidence the propensity of the spacer to stabilize the α-FAPbI3 perovskite phase in hybrid low-dimensional SFA n–1Pb n I3n+1 perovskite compositions. This has been investigated by means of solid-state nuclear magnetic resonance spectroscopy in conjunction with molecular dynamics simulations and density functional theory calculations. Theoretical calculations suggest an electronic contribution of the organic spacer to the resulting optoelectronic properties, which was confirmed by transient absorption spectroscopy. We have further analyzed these materials by time-resolved microwave conductivity measurements, revealing challenges for their application in photovoltaics.

Tuning Napththalenediimide Cations for Incorporation into Ruddlesden–Popper-Type Hybrid Perovskites

“…However, the incorporation of rylene-based dyes and the possible formation of layered perovskite films remain unclear as these highly planar molecules tend to aggregate in solution due to strong π–π interactionscompromising the formation of a layered perovskite structure. Indeed, the incorporation of symmetric naphthalenediimide (NDI)-based divalent cations using an ethylamine linker chain (NDIC2) was recently investigated and only a linearly linked PbI 6 perovskitoid structure was formed, likely due to the stacking effect of the NDIC2. , At the same time, recent research on benzodithiophene-based spacer cations suggests a strong effect of the amine-bearing alkyl chain length on the incorporation into a layered structure . Long alkyl chain spacer cations were found to be easier to incorporate into a layered perovskite resulting in films with higher crystallinity.…”

Dynamic Nuclear Polarization Enables NMR of Surface Passivating Agents on Hybrid Perovskite Thin Films

“…Nuclear magnetic resonance (NMR) is well suited to establish an atomic-level understanding of both the organic and inorganic components of hybrid perovskites, as well as dopants and additives. − Specifically, magic angle spinning (MAS) NMR has previously been applied to study cation incorporation, − phase segregation, ,− cation dynamics, − passivating layers, , degradation, , and phase transitions. − NMR has also been successful in probing bulk layered perovskites, ,, bulk 2D/3D perovskite heterostructures, − and the surfaces of perovskite nanocrystals. − However, the intrinsic insensitivity of NMR limits its utility to study thin-film samples as used in perovskite devices, owing to the very low sample mass. This insensitivity is compounded for the study of dopants and additives, which comprise only a small fraction of the sample.…”

“…32−35 Specifically, magic angle spinning (MAS) NMR has previously been applied to study cation incorporation, 36−41 phase segregation, 38,42−47 cation dynamics, 48−51 passivating layers, 31,52 degradation, 52,53 and phase transitions. 48−51 NMR has also been successful in probing bulk layered perovskites, 47,54,55 bulk 2D/3D perovskite heterostructures, 56−59 and the surfaces of perovskite nanocrystals. 60−62 However, the intrinsic insensitivity of NMR limits its utility to study thin-film samples as used in perovskite devices, owing to the very low sample mass.…”

Regulation of Quantum Wells Width Distribution in 2D Perovskite Films for Photovoltaic Application

“…Reproduced with permission. [ 98 ] Copyright 2021, American Chemical Society. F) Top‐view and cross‐sectional sketches of the manufacturing of a (BA) 2 PbI 4 film on a 3D perovskite substrate via the SIG method.…”

“…E) Schematic representation of the electronic structure based on typical type I (top) and type II (bottom) QW structures of layered perovskites with the gray area representing the HOMO and LUMO levels of the organic spacer and blue area representing the band edges of the inorganic slabs (left) and schematic representation of the layered perovskite material incorporating electroactive NDIEA-based moieties (right). Reproduced with permission [98]. Copyright 2021, American Chemical Society.…”