Illustrating the Key Role of Hydrogen Bonds in Fabricating Pure-Phase Two-Dimensional Perovskites

Abstract

Two-dimensional (2D) layered perovskites consisting of multiple quantum wells are emerging as functional materials to achieve high-performance and stable optoelectronic devices. Pure-phase 2D perovskites provide a platform to investigate their fundamental properties; however, the deposition of pure-phase films remains a scientific challenge. Herein, we reveal the critical role of hydrogen bonds in fabricating pure-phase 2D perovskites. We demonstrate that the phenylalkylammonium molecules exhibit different hydrogen bonding abilities with formamidinium (FA) by varying their alkyl chain lengths. The stronger hydrogen bonding-assisted FA localization at the corner of [PbBr6]4– octahedral layer plays a key role in the crystallization of n = 2 pure-phase perovskites. On the basis of these understandings, we demonstrate deep-blue electroluminescence with an emission peak at 442 nm and a narrow line width of 13 nm, showing a peak external quantum efficiency of 0.19%. This finding opens up a new avenue for domain distribution control of 2D perovskites.

Tailoring Pure-Phase Quasi-2D Perovskites via the Polymer Crystallization-Assisted Strategy

“…24,25 In 2022, Huang and co-workers successfully fabricated one species of PPQP (n = 2) thin films by utilizing the strong hydrogen bonds between the bulky and smallish cations. 26 Recently, numerous efforts have been devoted to pursuing the final uniform QW distribution in one sequential perovskite film. However, to date, the controllable fabrication of different n-value PPQP thin films remains an extremely formidable challenge.…”

“…Pure-phase quasi-2D perovskites (PPQPs) with high color purity can ultimately satisfy a wide range of the color gamut of light, which also provides a platform to investigate their fundamental properties. Despite the great success that has been made in synthesizing the PPQP single crystals (especially for n = 1, 2, and 3) by tuning the stoichiometric amounts of precursor, − there is still a crucial and difficult issue to realize the deposition of PPQP thin films. , In 2022, Huang and co-workers successfully fabricated one species of PPQP ( n = 2) thin films by utilizing the strong hydrogen bonds between the bulky and smallish cations . Recently, numerous efforts have been devoted to pursuing the final uniform QW distribution in one sequential perovskite film.…”

Odd–Even Alkyl Chain Effects on the Structure and Charge Carrier Transport of Two-Dimensional Sn-Based Perovskite Semiconductors

“…In recent years, several groups have reported the influence of the cation alkyl chain length on device performance. For instance, a higher external quantum efficiency of light-emitting diodes was observed for quasi-2D perovskites containing phenylalkylammonium-based cations with longer alkyl chains that established strong hydrogen bonding with the formamidinium cation . In another study, a series of linear aliphatic alkylammonium cation spacers with different chain lengths were investigated in quasi-2D perovskite solar cells, and the device efficiency was shown to increase with increasing the length of cations …”