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The spontaneous formation of self-assembly monolayer (SAM) on various substrates represents an effective strategy for interfacial engineering of optoelectronic devices. Hole-selective SAM is becoming popular among high-performance inverted perovskite solar cells (PSCs), but the presence of strong acidic anchors (such as -PO3H2) in state-of-the-art SAM is detrimental to device stability. Herein, we report for the first time that acidity-weakened boric acid can function as an alternative anchor to construct efficient SAM-based hole-selective contact (HSC) for PSCs. Theoretical calculations reveal that boric acid spontaneously chemisorbs onto indium tin oxide (ITO) surface with oxygen vacancies facilitating the adsorption progress. Spectroscopy and electrical measurements indicate that boric acid anchor significantly mitigates ITO corrosion. The excess boric acid containing molecules improves perovskite deposition and results in a coherent and well-passivated bottom interface, which boosts the fill factor (FF) performance for a variety of perovskite compositions. The optimal boric acid anchoring HSC (MTPA-BA) can achieve power conversion efficiency close to 23% with a high FF of 85.2%. More importantly, the devices show improved stability: 90% of their initial efficiency is retained after 2400 h storage (ISOS-D-1) or 400 h operation (ISOS-L-1), which are 5-fold higher than those of phosphoric acid SAM based devices. Acidity-weakened boric acid SAM, which are friendly to ITO, well exhibits great potential to improve stability of interface as well as device.

Narrow-bandgap tin-lead (Sn-Pb) mixed perovskite solar cells (PSCs) play a key role in constructing perovskite tandem solar cells that are potential to overpass Shockley-Queisser limit. A robust, chemically stable and low-temperature-processed hole transporting layer (HTL) is essential for building high-efficiency Sn-Pb solar cells and perovskite tandem solar cells. Here, we explore a room-temperature-processed NiO x (L-NiO x ) HTL based on nanocrystals (NCs) for Sn-Pb PSCs. In comparison with high-temperature-annealed NiO x (H-NiO x ) film, the L-NiO x film shows deeper valence band and lower trap density, which increases the built-in potential and reduces carrier recombination, leading to a power conversion efficiency of 18.77%, the record for NiO x -based narrow-bandgap PSCs. Furthermore, the device maintains about 96% of its original efficiency after 50 days. This work provides a robust and room-temperature-processed HTL for highly efficient and stable narrow-bandgap PSCs.

Summary With rapid progress in perovskite light-emitting diodes (PeLEDs), the electroluminescence performance of large-area is of increasing interest. We investigated why large-area performance lags behind that achieved in laboratory-scale devices and found that defects in perovskite films—emerging from thermal convection during solvent evaporation, as well as electronic traps formed during perovskite crystallization—are chief causes. Here, we report a molecular modification strategy that simultaneously eliminates pinholes in perovskite layers by controlling the dynamics of film formation and that passivates defects in perovskites by incorporating Br species, thereby preventing shorts and non-radiative recombination. The molecular modifier 1,3,5-tris (bromomethyl) benzene (TBB) also modulates the electronic structure of injection or transport materials to achieve improved charge injection and balanced charge transport. As a result, we demonstrate 20 mm × 20 mm green perovskite nanocrystal LEDs that achieve an external quantum efficiency (EQE) of over 16%, a record for large-area PeLEDs.

Tin perovskite is rising as a promising candidate to address the toxicity and theoretical efficiency limitation of lead perovskite. However, the voltage and efficiency of tin perovskite solar cells are much lower than lead counterparts. Herein, indene-C60 bisadduct with higher energy level is utilized as an electron transporting material for tin perovskite solar cells. It suppresses carrier concentration increase caused by remote doping, which significantly reduces interface carriers recombination. Moreover, indene-C60 bisadduct increases the maximum attainable photovoltage of the device. As a result, the use of indene-C60 bisadduct brings unprecedentedly high voltage of 0.94 V, which is over 50% higher than that of 0.6 V for device based on [6,6]-phenyl-C61-butyric acid methyl ester. The device shows a record power conversion efficiency of 12.4% reproduced in an accredited independent photovoltaic testing lab., Despite the lower device efficiency, tin perovskite based solar cells are preferred choices compared to lead-based counterparts due to much lower toxicity. Here Jiang et al. use a fullerene derivative to greatly suppress carrier interface recombination and obtain record high cell efficiency of 12%.

Author(s): Chambers, C; Walton, T; Fairbank, D; Craycraft, A; Yahne, DR; Todd, J; Iverson, A; Fairbank, W; Alamare, A; Albert, JB; Anton, G; Arnquist, IJ; Badhrees, I; Barbeau, PS; Beck, D; Belov, V; Bhatta, T; Bourque, F; Brodsky, JP; Brown, E; Brunner, T; Burenkov, A; Cao, GF; Cao, L; Cen, WR; Charlebois, SA; Chiu, M; Cleveland, B; Coon, M; Cree, W; Cote, M; Dalmasson, J; Daniels, T; Darroch, L; Daugherty, SJ; Daughhetee, J; Delaquis, S; Mesrobian-Kabakian, A Der; DeVoe, R; Dilling, J; Ding, YY; Dolinski, MJ; Dragone, A; Echevers, J; Fabris, L; Farine, J; Feyzbakhsh, S; Fontaine, R; Fudenberg, D; Giacomini, G; Gornea, R; Gratta, G; Hansen, EV; Heffner, M; Hoppe, EW; Hosl, J; House, A; Hufschmidt, P; Hughes, M; Ito, Y; Jamil, A; Jessiman, C; Jewell, MJ; Jiang, XS; Karelin, A; Kaufman, LJ; Kodroff, D; Koffas, T; Kravitz, S; Krucken, R; Kuchenkov, A; Kumar, KS; Lan, Y; Larson, A; Leonard, DS; Li, G; Li, S; Li, Z; Licciardi, C; Lin, YH; Lv, P; MacLellan, R; Michel, T; Mong, B; Moore, DC | Abstract: The search for neutrinoless double beta decay probes the fundamental properties of neutrinos, including whether or not the neutrino and antineutrino are distinct. Double beta detectors are large and expensive, so background reduction is essential for extracting the highest sensitivity. The identification, or 'tagging', of the $^{136}$Ba daughter atom from double beta decay of $^{136}$Xe provides a technique for eliminating backgrounds in the nEXO neutrinoless double beta decay experiment. The tagging scheme studied in this work utilizes a cryogenic probe to trap the barium atom in solid xenon, where the barium atom is tagged via fluorescence imaging in the solid xenon matrix. Here we demonstrate imaging and counting of individual atoms of barium in solid xenon by scanning a focused laser across a solid xenon matrix deposited on a sapphire window. When the laser sits on an individual atom, the fluorescence persists for $\sim$30~s before dropping abruptly to the background level, a clear confirmation of one-atom imaging. No barium fluorescence persists following evaporation of a barium deposit to a limit of $\leq$0.16\%. This is the first time that single atoms have been imaged in solid noble element. It establishes the basic principle of a barium tagging technique for nEXO.

Highlights Recent progress of efficiency and long-term stability for perovskite solar cells, and the development of perovskite-based tandem solar cells are described. The progress of lead-free perovskite solar cells and their potential for industrial production are discussed in detail. The current status, ongoing challenges, and the future outlooks of perovskite solar cells are highlighted., Perovskite solar cells (PSCs) emerging as a promising photovoltaic technology with high efficiency and low manufacturing cost have attracted the attention from all over the world. Both the efficiency and stability of PSCs have increased steadily in recent years, and the research on reducing lead leakage and developing eco-friendly lead-free perovskites pushes forward the commercialization of PSCs step by step. This review summarizes the main progress of PSCs in 2020 and 2021 from the aspects of efficiency, stability, perovskite-based tandem devices, and lead-free PSCs. Moreover, a brief discussion on the development of PSC modules and its challenges toward practical application is provided.

The optical responses of molecules and materials provide a basis for chemical measurement and imaging. The optical diffraction limit in conventional light microscopy is exceeded by mechanically probing optical absorption through the photothermal effect with atomic force microscopy (AFM). However, the spatial resolution of AFM-based photothermal optical microscopy is still limited, and the sample surface is prone to damage from scratching due to tip contact, particularly for measurements on soft matter. In this article, we develop peak force visible (PF-vis) microscopy for the measurement of visible optical absorption of soft matter. The spatial resolution of PF-vis microscopy is demonstrated to be 3 nm on green fluorescent protein-labeled virus-like particles, and the imaging sensitivity may approach a single protein molecule. On organic photovoltaic polymers, the spatial distribution of the optical absorption probed by PF-vis microscopy is found to be dependent on the diffusion ranges of excitons in the donor domain. Through finite element modeling and data analysis, the exciton diffusion range of organic photovoltaics can be directly extracted from PF-vis images, saving the need for complex and delicate sample preparations. PF-vis microscopy will enable high-resolution nano-imaging based on light absorption of fluorophores and chromophores, as well as deciphering the correlation between the spatial distribution of photothermal signals and underlying photophysical parameters at the tens of nanometer scale.

The power conversion efficiency (PCE) of tin perovskite solar cells is impeded by the extremely poor resistance to oxidation and high density of intrinsic Sn vacancies. Herein, we grow a 2D-quasi-2D-3D Sn perovskite film using removable pseudohalogen NH4SCN as a structure regulator. This hierarchy structure remarkably enhances air stability resulting from the parallel growth of 2D PEA(2)SnI(4) as the surface layer. We then explore the hierarchy structure perovskite films in planar structural solar cells, which generate a PCE up to 9.41%. The device retains 90% of its initial performance for almost 600 hr. Our results suggest that adding removable NH4SCN in a perovskite precursor can significantly improve the stability and photovoltaic performance of Sn perovskite. This finding provides a powerful strategy to manipulate the structure of low-dimensional perovskite in order to enhance the performance of perovskite solar cells.

The stability of perovskite is a bottleneck for the application of perovskite solar cells. Herein, 4-ethylamine Phenylphosphate disodium salt (EAPP) was explored as a functional surface ligand to passivate perovskite surface. As the addition of 1 mol% of EAPP, the degradation of the film in high humidity condition was effectively reduced. Solar cells based on EAPP doped perovskite film show merely slight decrease of its initial efficiency in high humidity condition, whereas the control device show catastrophic decrease. Apart from as a passivating molecule to protect perovskite from contacting with water, EAPP show function as a reducing reagent to bond with hydrogen iodide formed in perovskite decomposition.

Arsenic has recently received widespread attention due to its high toxicological effects on multiple animals; however, the mechanism underlying this toxicity is unclear. We investigated the damaging effects of arsenic trioxide (ATO) on hepatocytes and the effects of regulating autophagy on the hepatocyte damage induced by ATO exposure. First, we investigated the effects of ATO exposure (0, 0.6, 1.2, 2.4, and 4.8 μM) on the biochemical function and autophagy of chicken hepatocytes. The findings showed that as the concentration of ATO increased, the lactate dehydrogenase (LDH) concentration increased, more autophagosomes were observed via transmission electron microscopy (TEM), and the gene and protein expression levels of P62, LC3Ⅱ, and Beclin1 increased. Adding N-acetyl-l-cystine (NAC, 1 mM) attenuated autophagy and the hepatocyte damage induced by ATO. Then, we used rapamycin (Rapa) and 3-methylpurine (3-MA) to regulate the autophagy induced by exposure to 4.8 μM ATO and observed changes in the antioxidant capacity and apoptosis rate of chicken hepatocytes. Induction of autophagy reduced ATO-induced hepatocyte apoptosis but caused no significant effect on oxidative stress in chicken hepatocytes. Inhibition of autophagy exacerbated ATO-induced hepatocyte oxidative stress and apoptosis. These findings demonstrate that autophagy plays an important role in ATO-induced cell damage.

The development of photocatalysts that can effectively harvest visible light is essential for advances in high-efficiency solar-driven hydrogen generation. Herein, we synthesized water soluble CuInS2 (CIS) and Cu-In-Zn-S (CIZS) quantum dots (QDs) by using one-pot aqueous method. The CIZS QDs are well passivated by glutathione ligands and are highly stable in aqueous conditions. We subsequently applied these QDs as a light harvesting material for photocatalytic hydrogen generation. Unlike most small band gap materials that show extremely low efficiency, these new QDs display remarkable energy conversion efficiency in the visible and near-infrared regions. The external quantum efficiency at 650 nm is ∼1.5%, which, to the best of our knowledge, is the highest value achieved until now in the near-infrared region.

Although halide perovskite nanocrystals (NCs) are promising materials for optoelectronic devices, they suffer severely from chemical and phase instabilities. Moreover, the common capping ligands like oleic acid and oleylamine that encapsulate the NCs will form an insulating layer, precluding their utility in optoelectronic devices. To overcome these limitations, we develop a postsynthesis passivation process for CsPbI3 NCs by using a bidentate ligand, namely 2,2′-iminodibenzoic acid. Our passivated NCs exhibit narrow red photoluminescence with exceptional quantum yield (close to unity) and substantially improved stability. The passivated NCs enabled us to realize red light-emitting diodes (LEDs) with 5.02% external quantum efficiency and 748 cd/m2 luminance, surpassing by far LEDs made from the nonpassivated NCs.

Mixed lead-tin (Pb-Sn) perovskites present a promising strategy to extend the light-harvesting range of perovskite-based solar cells (PSCs). The use of electrontransporting layer or hole-transporting layer (HTL) is critical to achieve high device efficiency. This strategy, however, requires tedious layer-by-layer fabrication as well as high-temperature annealing for certain oxides. In this work, we fabricated HTL-free planar FAPb0.5Sn0.5I3 PSCs with the highest efficiency of 7.94%. High shortcircuit current density of 23.13 mA/cm2 was attained, indicating effective charge extraction at the ITO/FAPb0.5Sn0.5I3 interface. This finding provides an alternative strategy to simplify the manufacture of single-junction or tandem PSCs.

nEXO is a proposed tonne-scale neutrinoless double beta decay ($0\nu\beta\beta$) experiment using liquid ${}^{136}Xe$ (LXe) in a Time Projection Chamber (TPC) to read out ionization and scintillation signals. Between the field cage and the LXe vessel, a layer of LXe ("skin" LXe) is present, where no ionization signal is collected. Only scintillation photons are detected, owing to the lack of optical barrier around the field cage. In this work, we show that the light originating in the skin LXe region can be used to improve background discrimination by 5% over previous published estimates. This improvement comes from two elements. First, a fraction of the $\gamma$-ray background is removed by identifying light from interactions with an energy deposition in the skin LXe. Second, background from ${}^{222}Rn$ dissolved in the skin LXe can be efficiently rejected by tagging the $\alpha$ decay in the ${}^{214}Bi-{}^{214}Po$ chain in the skin LXe., Comment: 11 pages, 12 figures

Copper (Cu) is an essential trace element for most organisms. However, excessive Cu can be highly toxic. The purpose of this study was to elucidate the mechanism underlying Cu toxicity in the kidneys of rats after treatment with CuCl2 (15 [control], 30, 60, or 120 mg/kg in the diet) for 180 days. Histological and ultrastructural changes, antioxidant enzyme activity, and the mRNA and protein levels of apoptosis and autophagy-related genes were measured. The results showed that Cu exposure led to significant accumulation of copper in kidneys and disorganized kidney morphology. The activities of total anti-oxidation capacity (T-AOC) and superoxide dismutase (SOD) in the kidneys decreased significantly, while the malondialdehyde (MDA) content increased. Furthermore, excessive Cu markedly upregulated the expression of autophagy and apoptosis-related genes (LC3A, LC3B, ATG-5, Beclin-1, Caspase3, CytC, P53, Bax), but downregulated the expression of P62, mTOR and BCL-2. Moreover, the LC3B/LC3A, ATG-5, Beclin-1, P53, Caspase3 proteins were up-regulated while P62 was down-regulated in the kidney tissues of the treatment groups. Overall, these findings provide strong evidence that excess Cu can trigger autophagy and apoptosis via the mitochondrial pathway by inducing oxidative stress in rat kidneys.

The Dion-Jacobson quasi-2D structure improves the stability of perovskite light-emitting diodes., Organic-inorganic hybrid halide perovskites are emerging as promising materials for next-generation light-emitting diodes (LEDs). However, the poor stability of these materials has been the main obstacle challenging their application. Here, we performed first-principles calculations, revealing that the molecule dissociation energy of Dion-Jacobson (DJ) structure using 1,4-bis(aminomethyl)benzene molecules as bridging ligands is two times higher than the typical Ruddlesden-Popper (RP) structure based on phenylethylammonium ligands. Accordingly, LEDs based on the DJ structure show a half-lifetime over 100 hours, which is almost two orders of magnitude longer compared with those based on RP structural quasi–two-dimensional perovskite. To the best of our knowledge, this is the longest lifetime reported for all organic-inorganic hybrid perovskites operating at the current density, giving the highest external quantum efficiency (EQE) value. In situ tracking of the film composition in operation indicates that the DJ structure was maintained well after continuous operation under an electric field.

In this paper we report on the characterization of the Hamamatsu VUV4 (S/N: S13370-6152) Vacuum Ultra-Violet (VUV) sensitive Multi-Pixel Photon Counters (MPPC)s as part of the development of a solution for the detection of liquid xenon scintillation light for the nEXO experiment. Various MPPC features, such as: dark noise, gain, correlated avalanches, direct crosstalk and Photon Detection Efficiency (PDE) were measured in a dedicated setup at TRIUMF. MPPCs were characterized in the range 163 K ≤ T ≤ 233 K . At an over voltage of 3 . 1 ± 0 . 2 V and at T = 163 K we report a number of Correlated Avalanches (CAs) per pulse in the 1 μ s interval following the trigger pulse of 0 . 161 ± 0 . 005 . At the same settings the Dark-Noise (DN) rate is 0 . 137 ± 0 . 002 Hz/mm 2 . Both the number of CAs and the DN rate are within nEXO specifications. The PDE of the Hamamatsu VUV4 was measured for two different devices at T = 233 K for a mean wavelength of 189 ± 7 nm . At 3 . 6 ± 0 . 2 V and 3 . 5 ± 0 . 2 V of over voltage we report a PDE of 13 . 4 ± 2 . 6 % and 11 ± 2 % , corresponding to a saturation PDE of 14 . 8 ± 2 . 8 % and 12 . 2 ± 2 . 3 % , respectively. Both values are well below the 24 % saturation PDE advertised by Hamamatsu. More generally, the second device tested at 3 . 5 ± 0 . 2 V of over voltage is below the nEXO PDE requirement. The first one instead yields a PDE that is marginally close to meeting the nEXO specifications. This suggests that with modest improvements the Hamamatsu VUV4 MPPCs could be considered as an alternative to the FBK-LF Silicon Photo-Multipliers for the final design of the nEXO detector.

The application of colloidal quantum dots for light-emitting devices has attracted considerable attention in recent years, due to their unique optical properties such as size-dependent emission wavelength, sharp emission peak and high luminescent quantum yield. Tremendous efforts have been made to explore quantum dots for light-emission applications such as light-emitting diodes (LEDs) and light converters. The performance of quantum-dots-based light-emitting diodes (QD-LEDs) has been increasing rapidly in recent decades as the development of quantum-dots synthesis, surface-ligand engineering and device-architecture optimization. Recently, the external quantum efficiencies of red quantum-dots LEDs have exceeded 20.5% with good stability and narrow emission peak. In this review, we summarize the recent advances in QD-LEDs, focusing on quantum-dot surface engineering and device-architecture optimization.

Perovskites with the multi-cation composition of cesium (Cs), methylammonium (MA), and formamidinium (FA) (CsMAFA) are pursued for their high power conversion efficiencies, but they are limited by their thermal stability. To withstand damp-heat accelerated aging MA-free compositions such as CsFA are of interest, but these exhibit lower carrier diffusion lengths and thus lesser performance in photovoltaic devices. A band engineering strategy that overcomes limited carrier diffusion within inverted perovskite solar cells based on CsFA is reported. A joint experimental-computational study shows that treating the perovskite with an n-type molecular dopant increases band bending, shaping the electric field across the active layer to overcome limited diffusive transport. Using this strategy, CsFA solar cell devices with stabilized power conversion efficiencies of 20.3%, a high value for devices using CsFA active layers, are fabricated.

Perovskite solar cells (PSCs) have excellent photovoltaic properties. There are, however, challenges of materials cost and device stability to be solved before commercializing them. Utilizing low-cost inorganic hole transport materials (HTM) as a replacement for spiro-OMeTAD, and replacing the Au electrode with printable carbon could be important steps in this regard. For this purpose, CuInxGa1-xS2 (x = 1, 0.75, 0.5, 0.25, 0) nanoparticle layers are deposited as inorganic HTMs with carbon composite electrode as the back electrode. Photovoltaic properties of PSCs with CuInxGa1-xS2/Carbon hole collecting electrodes are studied by changing the In ratio in the HTM layer. Results from impedance spectroscopy show that by decreasing x value the charge transfer resistance at the interface of hole collector and perovskite layer decrease which matches the downward trend of fill factor of the corresponding cells. The efficiency of PSCs increases during the first week, while, on average, their efficiency drop after one month is less than 5% of the initial values. The best efficiency of 16.45% has been obtained for CuIn0.75Ga0.25S2/carbon hole collectors.

Characterization of the vacuum ultraviolet (VUV) reflectance of silicon photomultipliers (SiPMs) is important for large-scale SiPM-based photodetector systems. We report the angular dependence of the specular reflectance in a vacuum of SiPMs manufactured by Fondazionc Bruno Kessler (FBK) and Hamamatsu Photonics K.K. (HPK) over wavelengths ranging from 120 nm to 280 nm. Refractive index and extinction coefficient of the thin silicon-dioxide film deposited on the surface of the FBK SiPMs are derived from reflectance data of a FBK silicon wafer with the same deposited oxide film as SiPMs. The diffuse reflectance of SiPMs is also measured at 193 nm. We use the VUV spectral dependence of the optical constants to predict the reflectance of the FBK silicon wafer and FBK SiPMs in liquid xenon.

Understanding reflective properties of materials and photodetection efficiency (PDE) of photodetectors is important for optimizing energy resolution and sensitivity of the next generation neutrinoless double beta decay, direct detection dark matter, and neutrino oscillation experiments that will use noble liquid gases, such as nEXO, DARWIN, DarkSide-20k, and DUNE. Little information is currently available about reflectivity and PDE in liquid noble gases, because such measurements are difficult to conduct in a cryogenic environment and at short enough wavelengths. Here we report a measurement of specular reflectivity and relative PDE of Hamamatsu VUV4 silicon photomultipliers (SiPMs) with 50 micrometer micro-cells conducted with xenon scintillation light (~175 nm) in liquid xenon. The specular reflectivity at 15 deg. incidence of three samples of VUV4 SiPMs is found to be 30.4+/-1.4%, 28.6+/-1.3%, and 28.0+/-1.3%, respectively. The PDE at normal incidence differs by +/-8% (standard deviation) among the three devices. The angular dependence of the reflectivity and PDE was also measured for one of the SiPMs. Both the reflectivity and PDE decrease as the angle of incidence increases. This is the first measurement of an angular dependence of PDE and reflectivity of a SiPM in liquid xenon., Comment: 21 pages, 15 figures, 6 tables. As accepted by JINST

Quantum efficiencies of organic-inorganic hybrid lead halide perovskite light-emitting devices (LEDs) have increased significantly, but poor device operational stability still impedes their further development and application. All-inorganic perovskites show better stability than the hybrid counterparts, but the performance of their respective films used in LEDs is limited by the large perovskite grain sizes, which lowers the radiative recombination probability and results in grain boundary related trap states. We realize smooth and pinhole-free, small-grained inorganic perovskite films with improved photoluminescence quantum yield by introducing trifluoroacetate anions to effectively passivate surface defects and control the crystal growth. As a result, efficient green LEDs based on inorganic perovskite films achieve a high current efficiency of 32.0 cd A−1 corresponding to an external quantum efficiency of 10.5%. More importantly, our all-inorganic perovskite LEDs demonstrate a record operational lifetime, with a half-lifetime of over 250 h at an initial luminance of 100 cd m−2., All-inorganic cesium lead bromide perovskite based light-emitting diodes show improved operational stability but the film quality limits their performance. Here Wang et al. use trifluoroacetate anions to passivate defects and achieve excellent device performance and stability.

In this article, we developed a new nano spectroscopic technique, peak force visible (PF-vis) microscopy, which is based on the peak force tapping mode in an atomic force microscope to both visualize nanoscale morphology and estimate exciton diffusion lengths of donor domains in organic photovoltaic blends. Nano phase-separations in P3HT:PCBM and TFB:PCBM blend films were clearly revealed by PF-vis microscopy with a high spatial resolution less than 10 nm. A model that correlates PF-vis signal and the exciton diffusion length was also developed to estimate the diffusion lengths of P3HT and TFB to be 2.9±0.3 and 9.0±1.5 nm, respectively. PF-vis microscopy is expected to assist the evaluation of OPV materials, therefore accelerating the pace of innovation of OPVs.

Embedding quantum dots in a perovskite matrix yields efficient light emitters. Colloidal quantum dots (CQDs) are emerging as promising materials for constructing infrared sources in view of their tunable luminescence, high quantum efficiency and compatibility with solution processing1. However, CQD films available today suffer from a compromise between luminescence efficiency and charge transport, and this leads to unacceptably high power consumption. Here, we overcome this issue by embedding CQDs in a high-mobility hybrid perovskite matrix. The new composite enhances radiative recombination in the dots by preventing transport-assisted trapping losses; yet does so without increasing the turn-on voltage. Through compositional engineering of the mixed halide matrix, we achieve a record electroluminescence power conversion efficiency of 4.9%. This surpasses the performance of previously reported CQD near-infrared devices two-fold, indicating great potential for this hybrid QD-in-perovskite approach.

The present disclosure provides a composite material of a pre-formed crystalline or polycrystalline semiconductor particles embedded in a crystalline or polycrystalline perovskite matrix material. The pre-formed crystalline or polycrystalline semiconductor particles and and crystalline or polycrystalline perovskite being selected so that any lattice mismatch between the two lattices does not exceed about 10%. The pre-formed crystalline or polycrystalline semiconductor particles and said crystalline or polycrystalline perovskite matrix material have lattice planes that are substantially aligned.

A Cu‐doped, NiO‐based quantum dot light‐emitting diode (QLED) reported by Xuyong Yang and co‐workers in article number 1704278 exhibits a significant operating lifetime enhancement compared with organic PEDOT:PSS‐based QLEDs. Relying on an inorganic hole transport lay...

The next-generation Enriched Xenon Observatory (nEXO) is a proposed experiment to search for neutrinoless double beta ($0\nu\beta\beta$) decay in $^{136}$Xe with a target half-life sensitivity of approximately $10^{28}$ years using $5\times10^3$ kg of isotopically enriched liquid-xenon in a time projection chamber. This improvement of two orders of magnitude in sensitivity over current limits is obtained by a significant increase of the $^{136}$Xe mass, the monolithic and homogeneous configuration of the active medium, and the multi-parameter measurements of the interactions enabled by the time projection chamber. The detector concept and anticipated performance are presented based upon demonstrated realizable background rates., Comment: v2 as published

Organolead halide perovskites have emerged as potential building blocks for photovoltaic and optoelectronic devices. Yet the underlying fundamental physics is not well understood. There is lack of agreement on the electronic band structures and binding energies of coupled electron-hole pairs (excitons), which drive the photophysical processes. In this work, we conducted temperature-dependent reflectance and photoluminescence experiments on high-quality ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{\mathrm{PbBr}}_{3}$ single crystals. Two direct optical transitions corresponding to intrinsic free-excitons are clearly resolved, showing excellent consistence between the low-temperature ($T=10$ K) reflectance and photoluminescence spectra. Remarkably, the excitons have different binding energies and behave oppositely with temperature, suggesting distinctive origins. Moreover, the asymmetric photoluminescence profile is counterintuitively dominated by the high-energy exciton that is explained by a long relaxation time between levels and by the favorable generation rate of electron-hole pairs at the high-energy band. Our study opens access to the intrinsic properties of ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{\mathrm{PbBr}}_{3}$ and sheds light to reconcile the large range of binding energies reported on these emergent direct band-gap semiconductors.

Because of the rapid rise of the efficiency, perovskite solar cells are currently considered as the most promising next-generation photovoltaic technology. Much effort has been made to improve the efficiency and stability of perovskite solar cells. Here, it is demonstrated that the addition of a novel organic cation of 2-(6-bromo-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)ethan-1-ammonium iodide (2-NAM), which has strong Lewis acid and base interaction (between C=O and Pb) with perovskite, can effectively increase crystalline grain size and reduce charge carrier recombination of the double cation FA(0.83)MA(0.17)PbI(2.51)Br(0.49) perovskite film, thus boosting the efficiency from 17.1 +/- 0.8% to 18.6 +/- 0.9% for the 0.1 cm(2) cell and from 15.5 +/- 0.5% to 16.5 +/- 0.6% for the 1.0 cm(2) cell. The champion cell shows efficiencies of 20.0% and 17.6% with active areas of 0.1 and 1.0 cm(2), respectively. Moreover, the hysteresis behavior is suppressed and the stability is improved. The result provides a promising route to further elevate efficiency and stability of perovskite solar cells by the fine tuning of triple organic cations.

Since organic-inorganic halide perovskites were first used in the field of solar cells in 2009, they have emerged as the most promising high-efficiency and low-cost next-generation solar cells. However, even though conventional lead perovskite halide perovskite solar cells have achieved a record efficiency of 25.2%, there is scope for improvement in terms of the detrimental properties of their constituent heavy metals. In addition, their theoretic efficiencies are limited by the large bandgap. Tin perovskite has received considerable attention in recent years, due to its heavy-metal-free character and superior semiconductor properties, such as a suitable bandgap and a high carrier mobility. In order to fabricate tin perovskite solar cells (TPSCs) of high-efficiency, the major obstacles have to be overcome, including fast crystallization of tin perovskites, high p-type carrier concentration, and high defect density. Even if Sn2+ has similar electronic configuration as Pb2+, Sn2+ has two more active electrons, which render tin perovskite less stable. To deal with these problems many strategies are developed. Lewis bases, such as dimethyl sulfoxide, are widely used to slow down the crystallization rate of tin perovskite, while oxide protective layer and plentiful additives (e.g., SnF2, liquid formic acid, and hydrazine vapor) have been found to reduce their oxidation. Furthermore, low-dimension structure and device engineering have been verified effectively promote TPSCs performance. Owing to the aforementioned strategies, the efficiency and stabilities of TPSCs were improving rapidly over the past few years, which indicates that TPSCs are the most promising candidate of lead-free perovskite solar cells. Recently, the certified efficiency of TPSCs reached over 12%, which is the maximum value for lead-free perovskite solar cells. Herein, we discuss the crystal and band structures, as well as the optoelectronic properties of tin perovskites. Furthermore, recent representative studies on tin perovskite are introduced, along with the strategies employed to improve the conversion efficiency, including the achievements based on component modification, dimension control, crystallization engineering and device structure design. Finally, we highlight the challenges presented by tin perovskites and the possible paths to improve device performance.

Large-bandgap perovskites offer a route to improve the efficiency of energy capture in photovoltaics when employed in the front cell of perovskite-silicon tandems. Implementing perovskites as the front cell requires an inverted (p-i-n) architecture; this architecture is particularly effective at harnessing high-energy photons and is compatible with ionic-dopant-free transport layers. Here, a power conversion efficiency of 21.6% is reported, the highest among inverted perovskite solar cells (PSCs). Only by introducing a secondary amine into the perovskite structure to form MA(1-)(x)DMA(x)PbI(3) (MA is methylamine and DMA is dimethylamine) are defect density and carrier recombination suppressed to enable record performance. It is also found that the controlled inclusion of DMA increases the hydrophobicity and stability of films in ambient operating conditions: encapsulated devices maintain over 80% of their efficiency following 800 h of operation at the maximum power point, 30 times longer than reported in the best prior inverted PSCs. The unencapsulated devices show record operational stability in ambient air among PSCs.