High-Efficiency and Wavelength-Tunable Near-Infrared Emission of Lanthanide Ions Doped Lead-Free Halide Double Perovskite Nanocrystals toward Fluorescence Imaging

Abstract

Near-infrared (NIR) fluorescent materials show unique photophysical properties, which make them widely used in optical communication, night vision imaging, biomedicine, and other applications. However, the development of high-efficiency and wavelength-tunable NIR nanomaterials is still a challenge. Herein, a series of lanthanide ions doped Cs2AgIn0.99Bi0.01Cl6 double perovskite nanocrystals (DPNCs) with wavelength-tunable NIR light emission (800–1600 nm) have been synthesized. The optimal photoluminescence quantum yield (PLQY) of the DPNCs reaches 66.7%, which is a record value for DPNCs. It is mainly attributed to the contribution of NIR emission of lanthanide ions doped into DPNCs. More importantly, the series of NIR emission wavelengths of lanthanide ions doped Cs2AgIn0.99Bi0.01Cl6 DPNCs include not only shorter-wavelength NIR light (≤900 nm) but also longer-wavelength NIR light (>900 nm), which are more appropriate for foodstuff analysis and medical diagnosis applications. Furthermore, 11.2% Nd3+ doped Cs2AgIn0.99Bi0.01Cl6 DPNCs with the optimal PLQY were embedded in a polymethyl methacrylate (PMMA) polymer matrix (DPNCs@PMMA), and the stability of DPNCs modified by PMMA has been greatly improved. Finally, the 11.2% Nd3+ ions doped Cs2AgIn0.99Bi0.01Cl6 DPNCs@PMMA based NIR LEDs have demonstrated good night vision and human tissue penetration. This work indicates that lanthanide ions doped DPNCs have a potential in NIR light applications and could inspire future research to explore novel lanthanide ions doped semiconductor NCs based NIR LEDs.

Self-Trapped Excitons Mediated Energy Transfer to Sm3+ in Cs2AgIn(1–x)SmxCl6:Bi Double Perovskite Nanocrystals

“…In the case of DP:S4.1, a third component (τ 3 ∼ 373 ps) is necessary to fit the kinetic curve satisfactorily. This additional time constant in Sm 3+ -doped DP is attributed to the sensitization of Sm 3+ via a nonradiative energy-transfer pathway …”

“…This additional time constant in Sm 3+ -doped DP is attributed to the sensitization of Sm 3+ via a nonradiative energy-transfer pathway. 62 The mechanism of the luminescence process in Sm 3+ -doped Cs 2 AgInCl 6 :Bi NCs is proposed in Figure 4f based on the above observations. When Cs 2 AgInCl 6 :Bi is excited at 368 nm, Bi 3+ ions absorb the energy and further shift to STEs through nonradiative relaxation processes.…”

Tunable and Efficient Photoluminescence of Lanthanide-Doped Cs2NaScCl6 Double Perovskite Single Crystals toward Multifunctional Light-Emitting Diode Applications

“…While Figure d,e represented the interstitial doping condition and the coexistence of interstitial and substitutional doping at Sc sites, respectively. The corresponding defect formation energy ( E for ) was calculated using the following equation E normalf normalo normalr = E normalt normalo normalt ( C s 2 N a S c C l 6 + T b ) − E normalt normalo normalt ( C s 2 N a S c C l 6 ) + prefix∑ n i normalΔ μ i where E tot (Cs 2 NaScCl 6 + Tb) and E tot (Cs 2 NaScCl 6 ) are the total energy for Tb 3+ -doped and undoped Cs 2 NaScCl 6 systems and μ represents the chemical potential for atoms calculated as the corresponding crystal energy per atom. The calculated E for under different conditions are graphically depicted in Figure f.…”

Intrinsic stability of perovskite materials and their operational stability in light-emitting diodes

“…In another case, ultra-broadband light emission is observed by doping the double perovskites (DPs) with Ln 3+ ions. 173,174 Jin et al 173 discovered that Cs 2 AgInCl 6 double perovskite doping by Ln 3+ (Ln = La to Lu) and Bi 3+ shows ultra-broadband light emission ranging from 400 to 2000 nm wavelength. The Bi/Ln:Cs 2 AgInCl 6 (Ln = Er, Ho, Tm) double perovskite showed ultra-broadband continuous emission due to the 4f-4f transition of Ln 3+ ions with superior long-term stability.…”