Halide Double Perovskite Nanocrystals Doped with Rare‐Earth Ions for Multifunctional Applications

Abstract

Most lead-free halide double perovskite materials display low photoluminescence quantum yield (PLQY) due to the indirect bandgap or forbidden transition. Doping is an effective strategy to tailor the optical properties of materials. Herein, efficient blue-emitting Sb 3+ -doped Cs 2 NaInCl 6 nanocrystals (NCs) are selected as host, rare-earth (RE) ions (Sm 3+ , Eu 3+ , Tb 3+ , and Dy 3+ ) are incorporated into the host, and excellent PLQY of 80.1% is obtained. Femtosecond transient absorption measurement found that RE ions not only served as the activator ions but also filled the deep vacancy defects. Anti-counterfeiting, optical thermometry, and white-light-emitting diodes (WLEDs) are exhibited using these RE ions-doped halide double perovskite NCs. For the optical thermometry based on Sm 3+ -doped Cs 2 NaInCl 6 :Sb 3+ NCs, the maximum relative sensitivity is 0.753% K −1 , which is higher than those of most temperature-sensing materials. Moreover, the WLED fabricated by Sm 3+ -doped Cs 2 NaInCl 6 :Sb 3+ NCs@PMMA displays CIE color coordinates of (0.30, 0.28), a luminous efficiency of 37.5 lm W −1 , a CCT of 8035 K, and a CRI over 80, which indicate that Sm 3+ -doped Cs 2 NaInCl 6 :Sb 3+ NCs are promising single-component white-light-emitting phosphors for next-generation lighting and display technologies.

The unique luminescent properties and enhanced thermal stability of a novel all-inorganic perovskite CsCaCl3:Mn2+ for solid-state lighting applications

“…This distinct behavior leads to the exploration of CsCaCl 3 :Mn 2+ nanocrystals for optical thermometry. To this end, the fluorescence intensity ratio (FIR) technique is employed to establish a correlation between temperature and FIR, as elucidated by the equations: 34,35 …”

Lanthanide/Bismuth-Codoped Lead-Free Halide Double Perovskite Nanocrystals with Upconversion and Short-Wave Infrared Luminescence

“…For SWIR PL of Yb/ Er/Bi-codoped Cs 2 NaInCl 6 NCs, under ultraviolet irradiation, the S → P transition of Bi 3+ in the [BiCl 6 ] 3− octahedron is activated, which causes the carriers to be in the excited state, implying that there should be an energy-transfer process from the [BiCl 6 ] 3− -induced trap state to the [ErCl 6 ] 3− octahedron. This is a typical photophysical process in inorganic halide DPs containing both ns 2 electron dopants and lanthanides that has been reported, 12,13,22,24,41,42 and it is reasonable to deduce that the [BiCl 6 ] 3− -induced trap state is an STE state.…”

“…Recently, all-inorganic lead-free indium-based halide double perovskite (DP) Cs 2 MInCl 6 (M = Na or Ag) NCs have aroused scientific interest because of their three-dimensional structure, direct band gap, and unique optical and photoelectronic characteristics. − Unfortunately, the parity-forbidden transition of Cs 2 MInCl 6 NCs severely hinders their photon absorption processes, which is a critical issue for the very low luminescence efficiency of pristine DP NCs. , Remarkably, Tang’s group and Han’s group respectively doped Bi 3+ and codoped Bi 3+ /Na + ions into Cs 2 AgInCl 6 , which broke the parity-forbidden transition and passivated the defect trap state, thereby realizing the warm-white-light emission caused by self-trapped excitons (STEs). − Obviously, the doping/codoping strategy is an effective way to tailor and optimize the luminescence properties of Cs 2 MInCl 6 NCs. Subsequently, Saikia et al showed that Cs 2 NaInCl 6 has better UV radiation stability than Cs 2 AgInCl 6 .…”

“…Thus, Cs 2 NaInCl 6 NCs are selected as hosts in our work. In addition, lanthanide (Ln 3+ )-contained DP NCs have been extensively studied. − ,− Researches are mainly focused on how to further introduce lanthanide ions into Cs 2 NaInCl 6 DP NCs to broaden the photoluminescence (PL) spectra for broadband white-light emission in the visible region. ,− However, other luminescent properties, such as upconversion (UC) and downshifting short-wave infrared (SWIR) emission in In-based halide DP nanomaterials, have rarely been explored. Therefore, it is of great significance to develop environmentally friendly and highly efficient DP NCs with UC and SWIR PL and to elucidate the luminescence mechanism as well.…”

Spin Centers in Vanadium-Doped Cs2NaInCl6 Halide Double Perovskites

“…Doping halide double perovskites (HDPs) of the general formula Cs 2 B′ 1+ B″ 3+ X 6 (B′ 1+ = Na + , Ag + ; B″ 3+ = Bi 3+ , Sb 3+ , In 3+ ; and X = Cl – , Br 1– , I – ) with metal ions has recently emerged as a new avenue to tailor the physical properties of lead-free and solution-processed semiconducting perovskites, highlighting potential applications in optoelectronics and spintronics. − Incorporating transition-metal ions such as Fe 3+ , Cr 3+ , and V 3+ into a B″-site of an HDP host has led to many interesting properties, such as bandgap tuning, , efficient near-infrared light emissions, , and magnetic response . Nonetheless, many puzzles remain regarding the role of transition-metal doping/alloying of HDPs, apart from target applications expected from ideal metal-ion substitutions at the B′-site or B″-site (i.e., with the correct charge states and correct crystallographic positions).…”