Self-Trapped Exciton Emission in a Zero-Dimensional (TMA)₂SbCl₅·DMF Single Crystal and Molecular Dynamics Simulation of Structural Stability

Abstract

Lead-free lower-dimensional organic−inorganic metal halide materials have recently triggered intense research because of their excellent photophysical properties and chemical stability. Herein, we report a novel zero-dimensional (0D) organic−inorganic hybrid single crystal (TMA) 2 SbCl 5 •DMF (TMA = N(CH 3 ) 3 , DMF= HCON(CH 3 ) 2 ), which exhibits typical selftrapped exciton (STE) emission with an efficient yellow emission at 630 nm and high photoluminescence quantum yield (PLQY) of 67.2%. The dual STE emission is attributed to the singlet and triplet STEs in inorganic [SbCl 5 ] 2− , respectively. Further, an ab initio molecular dynamics simulation was performed to estimate the stability of crystal structure at room temperature. The calculated excited-state structure indicates that the deformation parameter (Δd) of the excited-state structure is larger than that of the ground state, illustrating the origin of a large Stokes shift. These results indicate that these new 0D lead-free organic−inorganic hybrid metal halides are promising luminescent materials for optoelectronic applications.

A Zero-Dimensional Organic Lead Bromide of (TPA)2PbBr4 Single Crystal with Bright Blue Emission

“…The result shows that the excited state of (TPA) 2 PbBr 4 is distorted, indicating that this compound has the potential to achieve broadband emis-sion. However, its deformation parameters are one order of magnitude smaller than (TMA) 2 SbCl 5 •DMF [33], which may be the dominant reasons for (TPA) 2 PbBr 4 having a small Stokes shift [36]. According to the detailed bond length data of Bmpip 2 PbBr 4 and (C 13 H 19 N 4 ) 2 PbBr 4 SCs, the deformation parameter (∆d) in the ground state is 24.3 × 10 −4 and 19.7 × 10 −4 , respectively, which are larger than (TPA) 2 PbBr 4 (8.098 × 10 −4 ).…”

“…Figure 3e shows the change of bond length of [PbBr4] 2− in the GS and excited state, and the changes of bond angles and bond length of GS and excited state are listed in Tables S5 and S6, respectively. Particularly, most bond lengths in the calculated excited The structural deformation degree of the excited state is related to the change of Stokes shift [33,34], and then we calculated the structural deformation parameter of the ground state (GS) and excited state to explain the observed small Stokes shift in (TPA) 2 PbBr 4 . Figure 3e shows the change of bond length of [PbBr 4 ] 2− in the GS and excited state, and the changes of bond angles and bond length of GS and excited state are listed in Tables S5 and S6, respectively.…”

(C16H28N)2SbCl5: A new lead-free zero-dimensional metal-halide hybrid with bright orange emission

“…where α i represents the angle of Cl-Sb-Cl in (C 16 H 28 N) 2 SbCl 5 . The calculated value of σ 2 is 6.45, which is larger than those of (TTA) 2 SbCl 5 (σ 2 = 4.98, TTA = tetraethylammonium) [20] and (TMA) 2 SbCl 5 •DMF (σ 2 = 5.3, TMA = trimethylamine) [21] in previous reports, illustrating that the lone pair in (C 16 H 28 N) 2 -SbCl 5 has higher chemical activity, and further ensures that this compound has strong exciton radiation recombination and high PLQE. Subsequently, the phase purity of (C 16 H 28 N) 2 SbCl 5 was verified by PXRD patterns (Fig.…”

Ambient-stable near Unity Photoluminescence Quantum Yield in Two-dimensional Tin Bromide Perovskites

“…8N8-DJ has a marginally higher lifetime of the charge carriers than 8N-RP. The PLQY of 8N8-DJ excels over the reported results of Sn-based layered perovskites (Table S6), [8][9][10][31][32][33][34][35][36][37][38][39][40] Pb-free organic-inorganic composites (Table S7), 23,[41][42][43][44] and Pbbased layered perovskites (Table S8), 7,[45][46][47][48][49][50] while that of the unstable 8N-RP perovskite is still comparable to the best reports.…”

“…The BE emission is due to emission from the spin and parity allowed 1 P1 excited state to the 1 S0 ground state, which is common for systems with ns 2 electronic configuration, here Sn 2+ (Figure 4c). 23,24 When the non-radiative electron capture by permanent deep trapsand electron transfer to the STE state are reducedat temperatures less than 150K, partial electron transfer can also occur from 1 P1 excited singlet state to the 3 P1 triplet state, followed by emission from 3 P1 to 1 S0.The self-trapped states are created by the overlapped discrete energy states below the conduction band because of strong carrier-phonon coupling. STE involves the transfer of charge carriers from the conduction band to these overlapped states and emission from the self-trapped state.…”