Tunable Dual‐Emission in Monodispersed Sb³⁺/Mn²⁺ Codoped Cs₂NaInCl₆ Perovskite Nanocrystals through an Energy Transfer Process

Abstract

Double halide perovskites are a class of promising semiconductors applied in photocatalysis, photovoltaic devices, and emitters to replace lead halide perovskites, owing to their nontoxicity and chemical stability. However, most double perovskites always exhibit low photoluminescence quantum efficiency (PLQE) due to the indirect bandgap structure or parity‐forbidden transition problem, limiting their further applications. Herein, the self‐trapped excitons emission of Cs2NaInCl6 by Sb‐doping, showing a blue emission with high PLQE of 84%, is improved. Further, Sb/Mn codoped Cs2NaInCl6 nanocrystals are successfully synthesized by the hot‐injection method, showing a tunable dual‐emission covering the white‐light spectrum. The studies of PL properties and dynamics reveal that an energy transfer process can occur between the self‐trapped excitons and dopants (Mn2+). The work provides a new perspective to design novel lead‐free double perovskites for realizing a unique white‐light emission.

Strong Self‐Trapped Exciton Emissions in Two‐Dimensional Na‐In Halide Perovskites Triggered by Antimony Doping

“…By nonlinear fitting of the temperature‐dependent PL spectra (Figure S17), the exciton binding energies ( E b ) can be obtained: 1n‐Sb =150 meV and 2n‐Sb =97 meV (Figure 3 f). Compared with the Sb‐doped doped 3D Cs 2 NaInCl 6 ( E b ≈86 meV), the exciton binding energy increases in the dimensional reduction process, which can be ascribed to the stronger quantum confinement for low‐dimensional materials [10b, 16, 30] . Meanwhile, a Huang–Rhys factor (S) of 52.3 for 1n‐Sb (Figure S18) was obtained, which is larger than other LDPs, reflecting stronger electron‐phonon coupling in 1n‐Sb [10b] …”

“…[10b] Different from Cs 2 NaInCl 6 , which has a cubic space group Fm " 3m, 2n and 1n crystallize in an orthorhombic space group C222 1 and a monoclinic space group P2 1 /c, respectively (Table S1). [16] The symmetry of the crystals decreases in the dimensional reduction process (n = 1 ! 1).…”

Mn2+‐Doped Metal Halide Perovskites: Structure, Photoluminescence, and Application

“…Thus, several kinds of metal ions including Cu 2+ , Ni 2+ , Mn 2+ and trivalent rare earth elements have been introduced into halide perovskites for obtaining ideal photophysical properties. [ 76–87 ] Among them, transition metal Mn 2+ ion is widely studied, because the presence of Mn 2+ ions will generate new optical features, moreover, it will produce new chemical and physical properties, including passivated grain boundaries or decreased defect state density, enhanced PLQY, and improved stabilities, which is important for the technological applications.…”

Lead‐free metal halide perovskites for light‐emitting diodes

“…Zhang et al 47 However, the PLQY of 0.6% is still limited even although they have already tried to control and optimize the performances of the NCs by varying the reaction temperature. The hot-injection method is also applied by Han et al 49 and Liu et al 50 to synthesis the double perovskite of Cs 2 NaInCl 6 . And they successfully obtained green emission at 535 nm and deep-blue emission at 445 nm by Ag + and Sb 3+ doping, respectively.…”