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Enhanced Photocurrent of All-Inorganic Two-Dimensional Perovskite Cs[subscript 2]PbI[subscript 2]Cl[
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Ag Intercalation in Layered Cs 3 Bi 2 Br 9 Perovskite for Enhanced Light Emission with Bound Interlayer Excitons
Cesium bismuth bromide (CBB) has garnered considerable attention as a vacancy-ordered layered perovskite with notable optoelectronic applications. However, its use as a light source has been limited due to its weak photoluminescence (PL). Here, we demonstrate metal intercalation as a novel approach to engineer the room-temperature PL of CBB using experimental and computational methods. Ag, when introduced into CBB, occupies vacant sites in the spacer region, forming octahedral coordination with surrounding Br anions. First-principles density functional theory calculations reveal that intercalated Ag represents the most energetically stable Ag species compared to other potential forms, such as Ag substituting Bi. The intercalated Ag forms a strong polaronic trap state close to the conduction band minimum and quickly captures photoexcited electrons with holes remaining in CBB layers, leading to the formation of a bound interlayer exciton, or BIE. The radiative recombination of this BIE exhibits bright room-temperature PL at 600 nm and a decay time of 38.6 ns, 35 times greater than that of free excitons, originating from the spatial separation of photocarriers by half a unit cell separation distance. The BIE as a new form of interlayer exciton is expected to inspire new research directions for vacancy-ordered perovskites.
Intrinsic Instability of Cs 2 In(I)M(III)X 6 (M = Bi, Sb; X = Halogen) Double Perovskites: A Combined Density Functional Theory and Experimental Study
Recently, there has been substantial interest in developing double-B-cation halide perovskites, which hold the potential to overcome the toxicity and instability issues inherent within emerging lead halide-based solar absorber materials. Among all double perovskites investigated, In(I)-based Cs2InBiCl6 and Cs2InSbCl6 have been proposed as promising thin-film photovoltaic absorber candidates, with computational examination predicting suitable materials properties, including direct bandgap and small effective masses for both electrons and holes. In this study, we report the intrinsic instability of Cs2In(I)M(III)X6 (M = Bi, Sb; X = halogen) double perovskites by a combination of density functional theory and experimental study. Our results suggest that the In(I)-based double perovskites are unstable against oxidation into In(III)-based compounds. Further, the results show the need to consider reduction–oxidation (redox) chemistry when predicting stability of new prospective electronic materials, especially when less common oxidation states are involved.
In Situ Measurement of Electric-Field Screening in Hysteresis-Free PTAA/FA 0.83 Cs 0.17 Pb(I 0.83 Br 0.17 ) 3 /C60 Perovskite Solar Cells Gives an Ion Mobility of ~3 × 10 –7 cm 2 /(V s), 2 Orders of Magnitude Faster than Reported for Metal-Oxide-Contacted Perovskite Cells with Hysteresis
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Order-disorder charge density wave instability in the kagome metal (Cs,Rb)V 3 Sb 5
The origin of the charge density wave phases in the kagome metal compound AV 3 Sb 5 is still under great scrutiny. Here, we combine diffuse and inelastic x-ray scattering to identify a 3-dimensional precursor of the charge order at the L point that condenses into a CDW through a first order phase transition. The quasi-elastic critical scattering indicates that the dominant contribution to the diffuse precursor is the elastic central peak without phonon softening. However, the inelastic spectra show a small broadening of the Einstein-type phonon mode on approaching T CDW . Our results point to the situation where the Fermi surface instability at the L point is of order-disorder type with critical growth of quasi-static domains. The experimental data indicate that the CDW consists on an alternating Star of David and trihexagonal distortions and its dynamics goes beyond the classical weak-coupling scenario and is discussed within strong-electron phonon coupling and non-adiabatic models.
Conventional superconductivity in the doped kagome superconductor Cs(V0.86Ta0.14)3Sb5 from vortex lattice studies
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Solution processing of air-stable molecular semiconducting iodosalts, Cs 2 SnI 6-x Br x , for potential solar cell applications
An effort to develop a new class of air-stable tin-based molecular semiconducting iodosalts for solar cell application.
Effect of AuBr 3 additive on the scintillation properties of BaBr 2 :Eu and Cs 2 LiLaBr 6 :Ce
The removal of vacancy-related defects by addition of AuBr3 to the melt during crystal growth impacts the performance of BaBr2:Eu and Cs2LiLaBr6:Ce very differently.
Degradation mechanisms in mixed-cation and mixed-halide Cs x FA 1−x Pb(Br y I 1−y ) 3 perovskite films under ambient conditions
With in situ ESEM and GIWAXS we saw that the perovskite degradation passes through hexagonal polytypes and is dependent on the composition.
TAGS measurements of 100 Nb ground and isomeric states and 140 Cs for neutrino physics with the new DTAS detector
In this work we report on total absorption γ -ray spectroscopy measurements of the β decay of fission products that are important contributors to the antineutrino spectrum. The experiment was performed at IGISOL as a part of a campaign of measurements with the new DTAS spectrometer. Preliminary results of the analysis of the β decay of 100 Nb, 100m Nb and 140Cs are presented.
Duty factor variation possibility from 1% to 100% with PKU microwave driven Cs-free volume H{sup −} sources
Microwave driven cesium-free volume H{sup −} sources, that have the ability to deliver tens of mA H{sup −} at 35 keV both in CW and 10% duty factor (100 Hz/1 ms), were developed at Peking University (PKU) [S. X. Peng et al., in Proceeding of IPAC 2015, WEPWA027, Richmond, Virginia, USA, 3–8 May 2015]. Recently, special efforts were paid on the investigation of duty factor variation possibility from 1% to 100% with them. Most of the experiments were carried out with a pulsed length (τ) of 1 ms and different intervals of 99 ms, 49 ms, 39 ms, 29 ms, 19 ms, 9 ms, 4 ms, 2 ms, 1 ms, 0.5 ms, and 0 ms, respectively. Other experiments were focused on CW operation and fixed duty factor of 1%. Experimental results prove that PKU H{sup −} sources can deliver tens of mA H{sup −} at duty factor from 1% to 100%. The RF power efficiency increases steadily with the increasing of duty factor from 1% to CW at a fixed pulsed length. Under a given duty factor and pulsed length, RF power efficiency keeps constant and the H{sup −} current increases with RF power linearly. Details will be presented in the paper.
Characterization and analysis of FA x Cs (1- x ) Pb(I y Br (1- y ) ) 3 perovskite solar cells with thickness controlled transport layers for performance optimization
Strong characterization methods are needed to fully comprehend the chemistry and composition of perovskite solar cells. Understanding the interaction between layers inside a cell and how they react with the environment is important to achieve optimum manufacturing processes, and improve efficiency of perovskite solar cells. Here, we probe a hybrid organic-inorganic perovskite cell structure formed by a fluorine-doped tin oxide (FTO), cassiterite (SnO 2 ), mixed halide perovskite, Spiro-OMeTAD and silver layers. We have demonstrated a power conversion efficiency (PCE) greater than 19% and aV oc of more than 1.1 V for a wide-band gap (1.6 eV) perovskite solar cell.
High quantum efficiency GaAs photocathodes activated with Cs, O2, and Te
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