Halide double perovskites have recently been developed as less toxic analogs of the lead perovskite solar-cell absorbers APbX3 (A = monovalent cation; X Br or I). However, all known halide large bandgaps that afford weak visible-light absorption. The first evaluated an absorber, Cs2AgBiBr6 (1), has a bandgap 1.95 eV. Here, we show dilute alloying decreases 1's by ca. 0.5 Importantly, time-resolved photoconductivity measurements reveal long-lived carriers with microsecond lifetimes in alloyed...

The impressive rise in efficiencies of solar cells employing the three-dimensional (3D) lead-iodide perovskite absorbers APbI3 (A = monovalent cation) has generated intense excitement. Although these perovskites have remarkable properties as solar-cell absorbers, their potential commercialization now requires a greater focus on materials' inherent shortcomings and environmental impact. This creates challenge an opportunity for synthetic chemists to address issues through design new...

Despite their compositional versatility, most halide double perovskites feature large band gaps. Herein, we describe a strategy for achieving small gaps in this family of materials. The new Cs2 AgTlX6 (X=Cl (1) and Br (2)) have direct 2.0 0.95 eV, respectively, which are approximately 1 eV lower than those analogous perovskites. To our knowledge, compound 2 displays the lowest gap any known perovskite. Unlike AI BII X3 perovskites, band-gap transition AI2 BB'X6 can show substantial...

Double perovskites, comprising two different cations, are potential nontoxic alternatives to lead halide perovskites. Here, we characterized thin films and crystals of Cs2AgBiBr6 by time-resolved microwave conductance (TRMC), which probes formation decay mobile charges upon pulsed irradiation. Optical excitation results in the with a yield times mobility product, φΣμ > 1 cm2/Vs. On millimeter-sized crystals, TRMC signals show, apart from fast decay, long-lived tail. Interestingly, this tail...

Molten phases of metal–organic networks offer exciting opportunities for using coordination chemistry principles to access liquids and glasses with unique tunable structures properties. Here, we discuss general thermodynamic strategies provide an increased enthalpic entropic driving force reversible, low-temperature melting transitions in extended solids illustrate this approach through a systematic study series bis(acetamide)-based record-low temperatures. The low temperatures these...

Pressure-induced thermal changes in solids-barocaloric effects-can be used to drive cooling cycles that offer a promising alternative traditional vapor-compression technologies. Efficient barocaloric requires materials undergo reversible phase transitions with large entropy changes, high sensitivity hydrostatic pressure, and minimal hysteresis, the combination of which has been challenging achieve existing materials. Here, we report new mechanism for achieving colossal effects leverages...

Sn alloying tunes a halide double perovskite to absorb visible light, in nontoxic composition.

We image charge carrier transport over nanometers–micrometers and picoseconds–microseconds in halide double perovskites Cs2AgBiBr6 Cs2AgTlBr6 single crystals using stroboscopic scattering microscopy. Both materials exhibit long, microsecond lifetimes because of their indirect or symmetry-forbidden direct bandgaps. extract free-charge trap-limited mobilities near the surface crystal bulk. The for both (∼10–50 cm2/(V s)) can reach those reported archetypal lead perovskites. measure trap...

Glassy phases of framework materials feature unique and tunable properties that are advantageous for gas separation membranes, solid electrolytes, phase-change memory applications. Here, we report a new guanidinium organosulfonate hydrogen-bonded organic (HOF) melts vitrifies below 100 °C. In this low-temperature regime, non-covalent interactions between guest molecules the porous become dominant contributor to overall stability structure, resulting in guest-dependent melting, glass,...

Halide double perovskites are an important emerging alternative to lead-halide in a variety of optoelectronic applications. Compared ABX3 single (A = monovalent cation, X halide), A2BB'X6 exhibit wider array compositions and electronic structures, promising finer control over physical properties through synthetic design. However, clear understanding how chemical composition dictates the structures this large family materials is still lacking. Herein, we develop qualitative Linear Combination...

Dopant defects in semiconductors can trap charge carriers or ionize to produce carriers─playing a critical role electronic transport. Halide perovskites are technologically important semiconductor family with large pressure response. Yet, our knowledge, the effect of high pressures on halide has not been experimentally investigated. Here, we study structural, optical, and consequences compressing small-bandgap double Cs2AgTlX6 (X = Cl Br) up 56 GPa. Mild compression 1.7 GPa increases...

Introduction of coal fly ash into aquatic systems poses a potential environmental hazard because its heavy metal content. Here we investigate the relationship between solid phase transformations, fluid composition, and release speciation during prolonged wet aging class C F ash. The causes rapid alkalinization water that is neutralized over time by CO(2) uptake from air calcite precipitation. resulting aqueous concentrations are below regulatory limits with exception Cr; solubility...

Owing to their high tunability and predictable structures, metal-organic materials offer a powerful platform study glass formation crystallization processes design glasses with unique properties. Here, we report novel series of glass-forming metal-ethylenebis(acetamide) networks that undergo reversible transitions below 200 °C. The glass-transition temperatures, kinetics, stability these are readily tunable, either by synthetic modification or liquid-phase blending, form binary glasses. Pair...

Abstract Despite their compositional versatility, most halide double perovskites feature large band gaps. Herein, we describe a strategy for achieving small gaps in this family of materials. The new Cs 2 AgTlX 6 (X=Cl ( 1 ) and Br )) have direct 2.0 0.95 eV, respectively, which are approximately eV lower than those analogous perovskites. To our knowledge, compound displays the lowest gap any known perovskite. Unlike A I B II X 3 perovskites, band‐gap transition BB′X can show substantial...

Abstract When the stakes are doubled in a wager, player must correctly place two consecutive bets to win, but payout is larger. Similarly, B sites combination dictate properties of A 2 BB′X 6 (A=monocation, X=halide) double perovskites. Correctly picking more challenging than just one, as I II X 3 single perovskites, options greater and, we believe, rewards higher when doubled. In this Minireview, emphasize fundamental aspects halide perovskites provide foundation for interested readers...

Understanding the factors that govern gas absorption in ionic liquids is critical to development of high-capacity solvents for catalysis, electrochemistry, and separations. Here, we report experimental probes liquid structure provide insights into how free volume impacts O2 properties liquids. Specifically, establish isothermal compressibility─measured rapidly accurately through small-angle X-ray scattering─reports on size distribution transient voids within a representative series...

Recent investigations into the effects of dimensional reduction on halide double perovskites have revealed an intriguing change in band structure when three-dimensional (3D) perovskite is reduced to a two-dimensional (2D) with inorganic sheets monolayer thickness (n = 1). The indirect bandgap 3D Cs2AgBiBr6 becomes direct n 1 whereas Cs2AgTlBr6 at limit. Here, we apply linear combination atomic orbitals approach uncover orbital basis for this symmetry transition reduction. We adapt our...

The response of an oxide crystal to the atmosphere can be personified as breathing─a dynamic equilibrium between O2 gas and O2– anions in solid. We characterize analogous defect reaction iodide double-perovskite semiconductor, Cs2SnI6. Here, I2 is released from at room temperature, forming iodine vacancies. vacancy a shallow electron donor therefore ionized temperature; thus, loss accompanied by spontaneous n-type self-doping. Conversely, high pressures, resorbed perovskite, consuming excess...

The halide double perovskite Cs2AgBiBr6 has emerged as a promising nontoxic alternative to the lead perovskites APbX3 (A = organic cation or Cs; X I Br). Here, we perform high-pressure synchrotron X-ray total scattering on and discover local disorder that is hidden from conventional Bragg analysis. While our powder diffraction data show average structure remains cubic up 2.1 GPa, analysis of pair distribution function reveals better described by monoclinic space group, with significant...

The unique chemistry of fluorocarbons (in particular, their weak intermolecular interactions and high degree intrinsic free volume) makes them promising building blocks for ionic liquids with gas capacities. Here, we report a generalizable method the synthesis fluorinated liquids, which relies on evolution gaseous byproducts to drive product formation. This synthetic strategy overcomes solubility challenges that can hinder highly via conventional methods enables systematic investigation...

We report the reactivity of copper azobispyridine (abpy) metallopolymers with nitrogen dioxide (NO2). The porous and conductive [Cu(abpy)]n mixed-valence undergo a redox reaction NO2, resulting in disproportionation NO2 gas. Solid- gas-phase vibrational spectroscopy X-ray analysis products NO2-dosed metallopolymer show evidence nitrate ions nitric oxide Exposure to results complete loss porosity decrease room-temperature conductivity by four orders magnitude character. Notably, can be...

Abstract Cs 2 AgBiBr 6 is prepared by reaction of CsBr, BiBr 3 , and AgBr in 9 M HBr solution (110 °C, h, 59% yield).