An Emerging Lead‐Free Double‐Perovskite Cs₂AgFeCl₆:In Single Crystal

Abstract

The recently emerged hybrid lead halide perovskites demonstrate low-cost fabrication and noteworthy performance, but they have intrinsically unstable properties and contain toxic Pb in a soluble form. Herein, a thus far unreported highly stable lead-free Cs 2 AgFeCl 6 double perovskite is developed. Its crystallographic structure and band structure are demonstrated to be capable of tuning by means of In 3+ incorporation. The as-prepared Cs 2 AgIn x Fe 1−x Cl 6 (0 ≤ x ≤ 1) perovskite single crystals display a broadband absorbance in the range of 450-800 nm, which further enables a remarkable enhancement of photoluminescence quantum yields by a factor of ≈167. Equally important, the incorporation of In atoms is experimentally and theoretically shown to improve the carriers transport ability, which is associated with the substitution of Fe-3d state by In-5s state in the energy range between 1.5 and 2.5 eV that dominates the conductive process, and thereafter may benefit the potential applications in photoelectronic and photovoltaic devices.

Lead‐Free Double Perovskite Cs2AgBiBr6: Fundamentals, Applications, and Perspectives

“…Additionally, magnetic ions such as Fe 3+ can also be alloyed with Bi 3+ or In 3+ to decrease the bandgap of double perovskites, however, the Fe 3+ alloyed samples are less likely to be used in optoelectronic fields because of the PL quenching effect of Fe 3+ . [108][109][110] Instead, they offer possibilities for potential spin-electronic applications, which will be discussed later.…”

The atomic-level structure of bandgap engineered double perovskite alloys Cs2AgIn1−xFexCl6

“…During the preparation of this manuscript, Fe 3+ -alloying strategy was reported to reduce the bandgap of double perovskite Cs 2 AgInCl 6 . 21 …”

“…Herein, we alloy magnetic ions (Fe 3+ -alloying) into the benchmark Cs 2 AgInCl 6 , 21 and tune the bandgap of Cs 2 AgIn 1− x Fe x Cl 6 over a range from 2.8 eV to 1.6 eV. We investigate the atomic-level structure of these double perovskite alloys using 133 Cs and 115 In ssNMR spectroscopy, where the paramagnetic Fe 3+ provides rich information on nuclear relaxation times.…”

Lead-Free Perovskite Single Crystals: A Brief Review

“…The fundamental lifetime of carrier recombination at room temperature attained a three-fold increase with the band gap remaining unchanged [44]. Furthermore, Yin et al synthesized Cs 2 AgIn x Fe 1−x Cl 6 (0 < x < 1) perovskite SCs employing a simple hydrothermal method, which exhibited a broadband absorbance from 450 to 800 nm and a huge enhancement of PLQY [45]. Luo et al prepared high quality Cs 2 AgInCl 6 SCs by space-confined hydrothermal method, achieving an ultra-low trap density of (8.6 ± 1.9) × 10 8 cm −3 and mobility of 3.31 cm 2 •V −1 •s −1 , respectively.…”