Guanine‐Stabilized Formamidinium Lead Iodide Perovskites

Abstract

Formamidinium (FA) lead iodide perovskite materials feature promising photovoltaic performances and superior thermal stabilities. However, conversion of the perovskite α‐FAPbI3 phase to the thermodynamically stable yet photovoltaically inactive δ‐FAPbI3 phase compromises the photovoltaic performance. A strategy is presented to address this challenge by using low‐dimensional hybrid perovskite materials comprising guaninium (G) organic spacer layers that act as stabilizers of the three‐dimensional α‐FAPbI3 phase. The underlying mode of interaction at the atomic level is unraveled by means of solid‐state nuclear magnetic resonance spectroscopy, X‐ray crystallography, transmission electron microscopy, molecular dynamics simulations, and DFT calculations. Low‐dimensional‐phase‐containing hybrid FAPbI3 perovskite solar cells are obtained with improved performance and enhanced long‐term stability.

Benzylammonium‐Mediated Formamidinium Lead Iodide Perovskite Phase Stabilization for Photovoltaics

“…[12,23] This limitation stimulated the appearance of another approach that involves forming 2D/3D perovskite composites of 3D perovskite compositions with 2D overlayers, which show good photovoltaic performance with improvement in their opera tional stability. [24][25][26][27][28][29] In this regard, 2phenylethylammonium (PEA) has been particularly effective (Figure 2a). [30][31][32][33] It has been shown that phenylalkylammonium analogues, e.g., ben zylamine and aniline, can impart the formamidinium (FA) lead iodide film surface with improved electronic properties and moisture resistance.…”

The Formation Mechanism of (001) Facet Dominated α‐FAPbI3 Film by Pseudohalide Ions for High‐Performance Perovskite Solar Cells

“…Hence, many efforts have focused on stabilizing the 𝛼-phase to achieve high-quality and phase-pure film. [11,12] Some researchers attempted to make compositional engineering by mixing with small radius cations, such as Cs + , Rb + , and MA + , to reduce lattice strain. [13][14][15] Among them, MAPbBr 3 with both smaller cations and anions is commonly used in the FAPbI 3 preparation to maximize 𝛼-phase stability.…”

Highly Orientational Order Perovskite Induced by In situ‐generated 1D Perovskitoid for Efficient and Stable Printable Photovoltaics

“…[17] Because of narrower light absorption range and high excitonic binding energy, LD perovskites are not ideal materials to apply directly on photovoltaic devices (PV). [18] Thus, it has been suggested to combine 2D and 3D perovskites to generate a 2D/3D heterostructure via additive engineering, [19,20] interfacial engineering, [21,22] or directly establishing a quasi-2D perovskite. [23,24] These strategies are particularly efficient in solving stability issues of 3D perovskite.…”