An Environmentally Stable and Lead‐Free Chalcogenide Perovskite

Abstract

Organic-inorganic halide perovskites are intrinsically unstable when exposed to moisture and/or light. Additionally, the presence of lead in many perovskites raises toxicity concerns. Herein is reported a thin film of BaZrS3, a lead-free chalcogenide perovskite.Photoluminescence and X-ray diffraction measurements show that BaZrS3 is far more stable than methylammonium lead iodide (MAPbI3) in moist environments. Moisture-and lightinduced degradations in BaZrS3 and MAPbI3 are compared by using simulations and calculations based on density functional theory. The simulations reveal drastically slower degradation in BaZrS3 due to two factorsweak interaction with water, and very low rates of ion migration. BaZrS3 photo-detecting devices with photo-responsivity of ~46.5 mA W -1 are also reported. The devices retain ~60% of their initial photo-response after 4 weeks in ambient conditions. Similar MAPbI3 devices degrade rapidly and show ~95% decrease in photoresponsivity in just 4 days. The findings establish the superior stability of BaZrS3 and strengthen the case for its use in optoelectronics. New possibilities for thermoelectric energy conversion using these materials are also demonstrated.

Chalcogenide Perovskites: Tantalizing Prospects, Challenging Materials

“…Sulfides: The most commonly synthesized sulfide perovskite is BaZrS 3 , which is reported to crystallize in the GdFeO 3 ‐type structure irrespective of the deposition method and temperature. [ 23,24,32,41,42,68–73 ] Similarly, BaHfS 3 has only been found in the GdFeO 3 ‐type phase by several authors. [ 23–25 ] By contrast, SrZrS 3 occurs in two distinct modifications depending on the growth process [ 70,92 ] —low‐temperature NH 4 CdCl 3 ‐type (α‐phase) and high temperature GdFeO 3 ‐type (β‐phase)—with the phase transition at about 980 °C.…”

“…[ 142 ] Gupta et al. [ 73 ] performed direct stability comparisons between BaZrS 3 and methylammonium lead iodide (MAPbI 3 ). They recorded photoluminescence (PL) intensity during ambient storage and steam exposure, as shown in Figure 8b.…”

Defect tolerance in chalcogenide perovskite photovoltaic material BaZrS3

“…Ti-doping has been attempted to optimize solar light absorption by reducing the band gap [31,36]. Thin films of BaZrS 3 have also been prepared with their electronic and optical properties being reported [37][38][39][40]. Encouragingly, SrHfS 3 has been experimentally demonstrated to exhibit excellent green light-emitting properties [41].…”

Chalcogenide Perovskites and Perovskite-Based Chalcohalide as Photoabsorbers: A Study of Their Properties, and Potential Photovoltaic Applications

“…In terms of stability in conditions rich in moisture, the thin film outperformed MAPbI 3 . Photodetectors were used to verify moisture-rich stability in which BaZrS 3 photodetectors lost ≈ 40% of their first ambient response after four weeks, while related MAPbI 3 photodetectors broke down by ≈95% in just four days [47]. However, Wei X et al prepared thin films of BaZrS 3 by sulfurizing oxide films lay down by a pulsed laser deposition (PLD) system at 800 • C. The films displayed remarkably intense light absorption with an absorption coefficient >10 5 cm −1 at photon energy >1.97 eV.…”