Tuning Optical Properties of Lead-Free 2D Tin-Based Perovskites with Carbon Chain Spacers

Abstract

We prepare a series of two-dimensional (2D) tin-based perovskite (RNH 2 ) 2 SnBr 4 with different carbon chains. All of them have extra-large Stokes shifts, broad emission, and ultralong PL lifetimes. The PLQYs of (C 8 H 17 NH 2 ) 2 SnBr 4 and (OAm) 2 SnBr 4 powders reach up to 54 and 60%, respectively. Density functional theory calculations and experimental results reveal that the properties of 2D Sn-based perovskites may originate from self-trapped excitons, which result from excited-state structural deformation. The results show that the [SnBr 6 ] 4− octahedron distorted by the carbon chain with arrangement distortion changes the photophysical properties of 2D tinbased perovskite. Furthermore, (OAm) 2 SnBr 4 powders are used to engineer UV pumped light-emitting diodes. This work provides new strategies for the preparation of environmentally friendly perovskite materials.

Alkylamine screening and zinc doping of highly luminescent 2D tin-halide perovskites for LED lighting

“…Therefore, we assumed that there were some non-ignorable non-radiative carrier trapping processes, which leaded to its lowest PLQY. 28,[41][42][43] The differences of PLQY and lifetime among these (RNH 3 ) 2 SnBr 4 indicated that the optical properties were influenced by the distortion of the structure.…”

“…S2. An obvious peak at 284 eV was related to C 1s; the peak of 400.9 eV was attributed to N 1s; the peaks located at 485.8 eV and 494.1 eV originated from Sn 3d of Sn 2+ ion; 26,28 the peak located at 67.5 eV was attributed to Br 3d. 35 According to integrated peak intensities, the elemental of the 2D (C 8 H 17 NH 3 ) 2 SnBr 4 perovskites ratio of N : Sn : Br was 4.4 : 1 : 5.6.…”

“…As shown in Table S1, with an increasing value of k r /k nr , the nonradiative pathways were suppressed, thus the PLQY of (RNH 3 ) 2 SnBr 4 increased. 28,[38][39][40] Table S1 showed that (C 6 H 13 NH 3 ) 2 SnBr 4 has the lowest k r /k nr value of 0.5385. Therefore, we assumed that there were some non-ignorable non-radiative carrier trapping processes, which leaded to its lowest PLQY.…”

“…In order to investigate the mechanism of broadband emission in our two-dimensional (2D) layered tin halide perovskites, we did a comprehensive review of the 2D perovskites which also showed broadband emission, Stokes shifts, and long lifetimes. 28,[44][45][46][47] Li et al reported 2D (RNH 3 ) 2 SnBr 4 perovskites and Density functional theory (DFT) study revealed that these properties originated from a strong phonon coupling in the deformable lattice, and considered as self-trapped excitons (STEs). 28 Multilayered lead iodide perovskites were investigated by temperature-dependent photoluminescence (PL) spectroscopy and transient absorption (TA) spectroscopy.…”

“…27 We noted that Li group reported the facile synthesis of 2D bulk tinhalide (RNH 3 ) 2 SnBr 4 perovskites and explored the effect of different carbon chains on 2D organic tin-halide perovskites. 28 The length of the organic amine chain will affect the transport of carriers, thereby affecting the device performance of the 2D tinhalide perovskites. 29 30 In addition, we thoroughly discussed the effects of Asite organic cations' substitution on their structural, optical properties and stability.…”