Tailoring the Broadband Emission in All‐Inorganic Lead‐Free 0D In‐Based Halides through Sb³⁺ Doping

Abstract

All‐inorganic lead‐free metal halides doped with ns2‐metal ions have shown great promise in optoelectronics and photovoltaics owing to their superior optical properties. Herein, a strategy is reported for tailoring the optical properties of 0D A2InX5⋅H2O and A3InX6 (A = Cs, Rb; X = Cl, Br) crystals via Sb3+ doping, and the excited‐state dynamics of Sb3+ is unveiled through temperature‐dependent photoluminescence (PL) and femtosecond transient absorption spectroscopies. Owing to the spatially confined 0D structure of the In‐based halides, Sb3+ ions experience a strong Jahn–Taller distortion on the excited state, which results in intense PL from Sb3+ with a broad emission band and a large Stokes shift. Through the control of A cation and the octahedral unit, tunable Sb3+ emissions (490−750 nm) with PL quantum yields up to 91.8% are achieved in these 0D In‐based halides. These findings provide fundamental insights into the excited‐state dynamics of Sb3+ in 0D metal halides, thus laying a foundation for future design of luminescent lead‐free 0D metal halides through ns2‐metal doping towards versatile applications.

Colloidal Synthesis and Tunable Multicolor Emission of Vacancy‐Ordered Cs2HfCl6 Perovskite Nanocrystals

“…The shortened lifetime with increasing Sb content may be due to the concentration quenching effect. [ 22 ] The PL excitation spectrum of Cs 2 HfCl 6 :0.10Sb 3+ NCs monitored at 628 nm (Figure S19, Supporting Information) show high‐energy photoexcitation peaks at 250, 270 nm and low‐energy photoexcitation peaks at 310, 330 nm, which should be attributed to the 1 S 0 ‒ 1 P 1 and 1 S 0 ‒ 3 P 1 transitions of Sb 3+ , respectively. [ 22,23 ] The tail from 400 to 600 nm is in line with the absorption tail (inset of Figure 3a), which may originate from NCs′ surface trap states.…”

Lead‐Free All‐Inorganic Indium Chloride Perovskite Variant Nanocrystals for Efficient Luminescence

“…Another newly emerging absorption peak of Sb‐doped NCs is observed at about 321 nm, which is ascribed to the spin–orbital allowed S→P transition of Sb 3+ in [SbCl 6 ] 3− octahedral sublattices. [ 36,40,41 ] Then, we examined the PL excitation (PLE) and PL measurements of (Rb x Cs 1− x ) 3 InCl 6 :Sb NCs. The PLE peak of the Sb‐doped NCs well matches with the absorption peak at ~321 nm (Figure S9, Supporting Information).…”

“…The large redshifted, broadband emission and the PL decay time on the order of microseconds are considered as the PL characteristics of self‐trapped excitons (STEs) or luminescence of ns 2 ‐metal ions. [ 31–36,42–47 ] It has been documented that In‐based halides without doping ns 2 ‐metal ions (Sb 3+ , Bi 3+ ) still have the large redshifted, broadband emission attributed to STEs. [ 31,44–49 ] After introducing ns 2 ‐metal ions, PL of the above In‐based halides only goes from weak to strong, not from nothing.…”

“…It is worth noting that all‐inorganic 0D In‐based halides bulk single crystals (SCs) have recently been reported and have excellent PL properties. [ 31–37 ] It provides the possibility to obtain high‐performance and good‐stability NCs. Subsequently, Cs 3 InBr 6 NCs and Rb 3 InCl 6 :Sb NCs have been independently synthesized via hot injection.…”

Broadband multimodal emission in Sb-doped CaZnOS-layered semiconductors

“…The blue light emission at 465 nm is attributed to the electron transition in the 3 P 1 → 1 S 0 process, and the band deformation occurs because the 3 P energy level is affected by the dynamic Jahn-Teller effect [40][41][42][43][44], which causes the three kinds of electron transition in the same 3 P energy level to the ground state 1 S 0 . Therefore, when excited by a 340-nm light wave, the valence electrons transfer from the ground state 1 S 0 to the excited state 3 P 1 , while most of the excited-state electrons return to the ground state 1 S 0 to emit a broad emission centred around of 465 nm.…”