T1.6 2D Dion-Jacobson Hybrid Lead Iodide Perovskites with Aromatic Diammonium Cations

Xiaotong Li (Northwestern University), Weijun Ke (Northwestern University),
Mercouri Kanatzidis (Northwestern University)

Two-dimensional (2D) halide perovskites have extraordinary optoelectronic properties and structural turnabilities. Among them, the Dion-Jacobson (DJ) phases incorporating diammonium cations with the inorganic layers stacking exactly on top of each other are less explored. When linear diammonium cations are incorporated, even though the carbon-chain is as short as four, the structure is still offset. Using cyclic diammonium cations instead, the DJ phases can be templated by the x-(aminomethyl)piperidinium (AMP) cations (x = 3 or 4). Furthermore, when the aromatic analogues ((x-(aminomethyl)pyridinium (AMPY) cations (x = 3 or 4)) are used instead of the aliphatic ones, the more symmetric 4AMPY cation can maintain the DJ structure. By modifying the position of the -CH₂NH₃⁺ group from 4AMPY to 3AMPY, the stacking of the inorganic layers changes from exactly eclipsed to slightly offset. The perovskite octahedra tilts are also different between the two series, with the less titled 3AMPY series exhibiting smaller bandgaps than the 4AMPY series. Compared to the aliphatic AMP cations, the xAMPY C-C bonds are shorter because of the aromaticity of the pyridine ring, and they bring the inorganic layers even closer to one another (< 4 Å). Another feature caused by the aromatic cations is a decrease in the exciton binding energy which is attributed to the increased dielectric constant. Taking all these factors into consideration, we also fabricated preliminary solar cell devices using the n=4 members as solar absorbers. The device based on (3AMPY)(MA)₃Pb₄I₁₃ showed a champion power conversion efficiency (PCE) of 9.20 %, which is higher than the (4AMPY)(MA)₃Pb₄I₁₃and the corresponding aliphatic analogue (3AMP)(MA)₃Pb₄I₁₃ based ones.

Event Timeslots (1)

SYMPOSIUM T1 – MATERIALS FOR OPTOELECTRONICS
4:40 pm - 5:00 pm
Xiaotong Li
Location: Technological Institute LR4