KBaTeBiO₆: A Lead-Free, Inorganic Double-Perovskite Semiconductor for Photovoltaic Applications

Abstract

Solar cells made up of lead-halide perovskites have shown a remarkable increase in power conversion efficiency; however, they are plagued with instability issues that, combined with the toxicity of lead, have led to a search for new semiconductors made up of heavy and nontoxic metals such as bismuth. Here, we report on a new, inorganic, double perovskite oxide semiconductor: KBaTeBiO 6 , which has an experimental indirect band gap of 1.88 eV and shows excellent stability. We combined data analytics and high throughput density functional theory calculations to search through thousands of hypothetical inorganic double perovskite oxides containing bismuth and predict KBaTeBiO 6 as a potential photovoltaic material, which was subsequently synthesized using a wet-chemistry route. The calculated effective mass of the charge carriers for KBaTeBiO 6 is comparable to the best performing Bi-halide double perovskites. Our work demonstrates the untapped potential of inorganic Bi-based double perovskite oxidesthat offer the ability to change both the cation combination and their stoichiometry to achieve desired electronic propertiesas exciting, benign, and stable alternatives to lead-halide perovskites for various semiconducting applications.

Earth-abundant non-toxic perovskite nanocrystals for solution processed solar cells

“…KBaTeBiO 6 and Bi 13 S 18 I 2 NCs have been used as dyes in DSSC devices employing the same counter electrode, solar cell area (0.25 cm 2 ), and a similar electrolyte, based on the I À /I 3 À couple. 97,100 The device incorporating the KBaTeBiO 6 NCs showed very low current probably because of the presence of defects in the crystalline structure, coming from the lack of control over the composition of the mixed oxide, and on the…”

“…The average efficiency obtained was 0.04%, with a best efficiency of 0.06% for the material dispersed without binders. 97 This may appear as a very low value, especially as compared to the 14.3% record efficiency for DSSCs, 66 and to the 6.5% achieved employing MAPbI 3 as sensitizer in DSSC. 98 However, KBaTeBiO 6 NCs show better material stability than bismuth-based halide perovskites and their solar cells show similar performance to those based on high quality thin films of other inorganic oxide perovskites.…”

A Perspective on the Commercial Viability of Perovskite Solar Cells

“…Compared with its halide counterpart, oxide perovskites demonstrated superior durability, where no structural changes were observed up to 1 year, given their high . [ 403,406 ] However, the indirect gap and the relatively larger bandgap do not make this system attractive for PV applications. Most of the oxide perovskite‐based PSCs, also known as ferroelectric oxide PV (FeOP), offered PCE < 1%, doubting their applicability to be developed into useful PSCs.…”

“…Currently, these simulation software are used mainly to determine new perovskite materials with suitable optoelectronic properties, as well as explain intrinsic factors that lead to specific behavior of PSCs. [406,591,592] Underlying mechanisms investigated through some in situ techniques in halide perovskite PSCs during operation could be unraveled in great detail using simulation, giving detailed insight into how to further improve both the PSC performance and durability. [593] It is apparent that simulation will be a vital element in future research and can augment the traditional experiments in material discovery process.…”

Tin Oxynitride-based Ferroelectric Semiconductors for Solar Energy Conversion Applications

“…26,27 Hence, there is ongoing search for stable, lead-free perovskites that can emulate the performance of leadhalide perovskite-based semiconductors. 3,[28][29][30][31][32][33] Such searches, for the most part, have been restricted to perovskite halides of heavier p-block cations such as Ge, Sn, and Bi. The band edges of such compounds are made up of spatially delocalized s or p states which combine with the threedimensional corner connectivity of the perovskite framework to create dispersive bands with low carrier effective masses.…”