Strongly Luminescent Dion–Jacobson Tin Bromide Perovskite Microcrystals Induced by Molecular Proton Donors Chloroform and Dichloromethane

Abstract

Lead‐free 2D perovskites based on tin halide octahedron slabs with Dion–Jacobson (DJ) phases have drawn attention due to their improved stability; still, reports on light‐emitting DJ lead‐free perovskites are scarce. Herein, a room‐temperature ligand assisted re‐precipitation method is used to produce ODASnBr4 perovskite microcrystals (ODA denotes protonated 1,8‐octanediamine). After incorporating molecular dopants chloroform and dichloromethane, not only the crystallinity of the DJ perovskite phase improves, but their emission becomes much stronger due to the formation of hydrogen bonds between [SnBr6]4− octahedra and acidic CH proton donors. ODASnBr4 microcrystals doped with these molecules show a high photoluminescence quantum yield (PLQY) approaching 90%, and their emission remains stable under a continuous UV irradiation, with less than 10% loss in intensity over 6 h. Moreover, by tuning the pristine ODASnBr4 with various degrees of exposure to the molecular dopants, the maximum of their self‐trapped exciton emission can be fine‐tuned over a spectral range of 570–608 nm while maintaining high PLQYs of 83–88%. This provides a convenient way to adjust the spectral position of DJ perovskite emission without changing halides or A‐site spacers. Thus, stable and strongly emitting lead‐free DJ perovskite materials have been developed.

Highly luminescent broadband phosphors based on acid solvent coordinated two-dimensional layered tin-based perovskites

“…S1, ESI†). 26–29 The fixed excitons produced in ODASnBr 4 have a low probability of interacting with inherent defects, leading to a high PLQY of 98.22% observed in the experiment (Fig. 2c).…”

“…The reflectance of the material is R , which is equal to % R /100. 28 An absorption peak at 303 nm with a broad shoulder at 347 nm was observed. From the PLE spectrum, it can be seen that the ODASnBr 4 sample exhibits three apparent PLE peaks at 290, 319 and 335 nm, which is similar to previously reported ODASnBr 4 microcrystals.…”

“…From the PLE spectrum, it can be seen that the ODASnBr 4 sample exhibits three apparent PLE peaks at 290, 319 and 335 nm, which is similar to previously reported ODASnBr 4 microcrystals. 28,29 The PL peak of the ODASnBr 4 sample is located at 586 nm. This indicates that the Stokes shift between the PLE and PL maxima is certainly over 250 nm.…”

“…These properties are attributed to the recombination from the self-trapped exciton (STE) state due to the lattice deformation and carrier–phonon coupling. 26–30 Absorbing energy under the irradiation of light, electrons are excited from the ground state to a variety of excited states, and then through direct relaxation, or thermal activation and tunnelling across a certain level of potential barrier of exciton binding energy ( E b ) that transforms free excitons to STEs. 2D perovskites can be divided into the Ruddlesden–Popper (RP) phase and the Dion–Jacobson (DJ) phase.…”

“…31,32 In addition, it has been shown that DJ phase has a higher stability than the RP phase because their extended divalent organic cations are connected with inorganic perovskite layers via hydrogen bonds rather than van der Waals interactions. 28 Very recently, DJ phase ODASnBr 4 (ODA denotes protonated 1,8-octanediamine) microcrystals have been reported via a ligand assisted re-precipitation method, 28 an argon gas assisted saturation recrystallization method 29 and a wet grinding method. 33 The final product prepared by the above methods contains impurities.…”