Yb- and Mn-Doped Lead-Free Double Perovskite Cs₂AgBiX₆ (X = Cl^–, Br^–) Nanocrystals

Abstract

Lead-free double perovskite nanocrystals (NCs) have emerged as a new category of materials that hold the potential for overcoming the instability and toxicity issues of lead-based counterparts. Doping chemistry represents a unique avenue toward tuning and optimizing the intrinsic optical and electronic properties of semiconductor materials. In this study, we report the first example of doping Yb 3+ ions into lead-free double perovskite Cs 2 AgBiX 6 (X = Cl − , Br − ) NCs via a hot injection method. The doping of Yb 3+ endows the double perovskite NCs with a newly emerged near-infrared emission band (sensitized from the NC hosts) in addition to their intrinsic trap-related visible photoluminescence. By controlling the Yb-doping concentration, the dual emission profiles and photon relaxation dynamics of the double perovskite NCs can be systematically tuned. Furthermore, we have successfully inserted divalent Mn 2+ ions in Cs 2 AgBiCl 6 NCs and observed emergence of dopant emission. Our work illustrates an effective and facile route toward modifying and optimizing optical properties of double perovskite Cs 2 AgBiX 6 (X = Cl − , Br − ) NCs with an indirect bandgap nature, which can broaden a range of their potential applications in optoelectronic devices.

Lanthanide doping in metal halide perovskite nanocrystals: spectral shifting, quantum cutting and optoelectronic applications

“…5f), but again with poor (<1%) PL QY. Yb 3+ doping (and codoping with Mn 2+ ions) has also been achieved in Cs 2 AgBiX 6 (X = Cl, Br) NCs with an indirect band gap, but the PL QY has not been reported 59 . Better synthesis protocols reducing the nonradiative decay channels are desired to upgrade the optical and optoelectronic properties of lanthanide-doped metal halide double perovskite NCs.…”

Lead‐Free Double Perovskites for Perovskite Solar Cells

“…The defective trapped states in doped Cs 2 AgInCl 6 NCs led to incapable energy transfer from Cs 2 AgInCl 6 to lanthanide dopants. Similarly, Chen et al doped Yb 3+ in the Cs 2 AgBiCl 6 and Cs 2 AgBiI 6 NCs via the hot injection method to produce a dual‐emission profile which was opposite to the results of the last work . In addition to the intrinsic trap states‐induced visible PL emission (≈680 nm) of undoped double perovskite, 2 F 5/2 – 2 F 7/2 f–f transition produced a NIR emission at ≈1000 nm, implying the energy transfer from Cs 2 AgBiCl 6 or Cs 2 AgBiI 6 to Yb 3+ dopant.…”

Device Engineering for All-Inorganic Perovskite Light-Emitting Diodes

“…To boost the efficiency, the charge injection, transport, balance and leakage should be carefully manipulated, which is also beneficial to the efficiency roll-off, color stability and lifetime. To solve the issue of toxicity, lead-free all-inorganic perovskites are helpful, although their performance is not satisfactory enough [245,246,247,248,249,250,251,252,253,254,255,256,257,258].…”