Defect Passivation in Air‐Stable Tin(IV)‐Halide Single Crystal for Emissive Self‐Trapped Excitons

Abstract

Tin(IV)-based metal halides are promising optoelectronic materials due to their robust structure and eco-friendly nature, but these materials exhibit poor photoluminescence (PL) properties and the underlying mechanisms are still elusive. Here, a novel air-stable hybrid Sn 4+ -halide material (C 8 H 22 N 2 Cl) 2 SnCl 6 that is resistant to moisture (>70% relative humidity) for >1 year is reported. The inferior PL property of (C 8 H 22 N 2 Cl) 2 SnCl 6 is limited by the lattice defects and robust crystal structure, which however could be effectively improved by introducing Sb 3+ ion with stereoactive 5s 2 lone pair. As a result, Sb 3+doped (C 8 H 22 N 2 Cl) 2 SnCl 6 exhibits a superbly stable room-temperature PL centered at 690 nm with an unprecedented quantum yield (QY) of 41.76% from self-trapped excitons, which is the highest PLQY of hybrid tin(IV)-based perovskite materials. The improved PL efficiency is attributed to the defect passivation and remarkable structure distortion induced by Sb 3+ dopants. This dopant-induced defect passivation and exciton self-trapping approach offers an avenue to improve optoelectronic material performance.

Antimony doping to enhance luminescence of tin(iv)-based hybrid metal halides

“…After doping, due to the highly active 5s 2 lone pair of Sb(III), the probability of electron transition to the excitation state was enhanced, resulting in more effective emission. 28 Alternatively, from the perspective of the widely accepted STE emission, which can be alternatively expressed as ns 2 emission in lone-pair-containing isolated cations, the octahedral distortion plays a crucial role in the formation of self-trapped excitons. [39][40][41] The structure of (C 9 H 15 N 3 ) 2 (Sn 0.77 Sb 0.23 )Cl 8 , with a nominal formula of (C 9 H 15 N 3 ) 2 (Sn 0.75 Sb 0.25 )Cl 8 from single-crystal diffraction (Table 1), exhibited greater distortion (λ oct = 7.64 × 10 −5 and σ 2 = 3.06) than the undoped sample (Fig.…”

“…Because the Sb 3+ ion has the advantages of being non-toxic and stable and exhibiting efficient broadband ns 2 emission, it was used as a dopant to improve the PL of the obtained compounds. 27,28 Using the above ideas, (C 9 H 15 N 3 ) 2 SnCl 8 and (C 9 H 15 N 3 ) 2 SnBr 8 were synthesized, both of which have 0D structures with Sn-based octahedra and halide anions separated by organic cations. Optical characterization revealed that both compounds exhibited very low PL at room temperature.…”

“…Because the Sb 3+ ion has the advantages of being non-toxic and stable and exhibiting efficient broadband n s 2 emission, it was used as a dopant to improve the PL of the obtained compounds. 27,28…”

Bright Green Emission from Self-Trapped Excitons Triggered by Sb3+ Doping in Rb4CdCl6

“…In fact, the stereochemically active lone pair 5s 2 electrons in Sb 3+ can alter the structural rigidity into a softer one, leading to the strong STEs emission from the host. 17,24 Presently, the luminescence of all-inorganic cadmium halides is seldom discussed, let alone the luminescent mechanism involved. In 1998, Kutsyk and Pidzyrailo reported on the luminescence of TlCdI 3 at 77 K. 25 Although the luminescence investigation of all-inorganic cadmium halides has been expanded to the doping engineering exploration, there seems to be a large gap in the study of luminescence for such materials.…”

Soft crystal lattice and large anharmonicity facilitate the self-trapped excitonic emission in ultrathin 2D nanoplates of RbPb2Br5

“…Temperature-dependent PL spectra measured in the range of 15-350 K show a monotonous decrease in PL intensity and an increase in FWHM with increasing temperature indicating the increased probability of nonradiative relaxation and stronger electron-phonon coupling at higher temperature, respectively. 36,42,46 Simultaneously, a slight blue shi in the emission peak is observed with the increase in temperature (Fig. 4a).…”