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Muons are part of natural cosmic radiation but can also be generated at spallation sources for material science and particle physics applications. Recently, pulsed muons have been used to characterize the density of free charge carriers in semiconductors and their recombination lifetime. Muon beam irradiation can also result in the formation of dilute levels of crystal defects in silicon. These crystal defects are only detected in high carrier lifetime silicon samples that are highly sensitive to defects due to their long recombination lifetimes. This work investigates the characteristics of these defects in terms of their formation, recombination activity, and deactivation. Charge carrier lifetime assessments and photoluminescence imaging have great sensitivity to measure the generated defects in high-quality silicon samples exposed to ∼4 MeV (anti)muons and their recombination activity despite the extremely low concentration. The defects reduce the effective charge carrier lifetime of both p- and n-type silicon and appear to be more detrimental to n-type silicon. Defects are created by transmission of muons through the wafer, and there are indications that slowed or implanted muons may create additional defects. In a post-exposure isochronal annealing study, we observe that annealing at temperatures of up to 450 °C does not by itself fully deactivate the defects. A recovery of charge carrier lifetime was observed when the annealing was combined with Al2O3 surface passivation, probably due to passivation of bulk defects from hydrogen from the dielectric film. [ABSTRACT FROM AUTHOR]

InGaN micro-LEDs (μ LEDs) with their potential high-volume applications have attracted substantial research interest in the past years. In comparison to other III–V semiconductors, InGaN exhibits a reduced susceptibility toward non-radiative surface recombination. However, efficiency degradation becomes more prominent as dimensions shrink to a few μ m or less. Due to the high surface-to-volume ratio of the miniaturized devices, the non-radiative recombination increases and reduces the internal quantum efficiency. While many groups focus on surface passivation to mitigate surface defects, the influence of crystallographic orientation of the μ LED sidewall on the efficiency remains unexplored. This study addresses this gap by investigating the impact of crystallographic orientation of the sidewalls on the emission properties of the μ LEDs. Hexagonal and elongated μ LEDs with dimensions as small as 3.5 μ m and sidewalls with crystallographically well-defined m- and a-planes were fabricated. Electrical and optical properties were investigated using photo- and electroluminescence. External quantum efficiency (EQE) is assessed based on well-known carrier recombination models. It can be shown that μ LED performance intrinsically depends on the crystallographic orientation of the sidewalls. Comparing hexagonal μ LED structures with a-plane and m-plane sidewalls, an increase in the EQE by 33 % was observed for structures with a-plane sidewalls, accompanied by reduction in the current density of the peak EQE by a nearly two orders of magnitude compared to structures with m-plane sidewalls. By analyzing the EQE characteristics at the μ LED center and near the sidewalls, the improvements can be directly attributed to the increased radiative recombination from sidewalls with a-plane orientation. [ABSTRACT FROM AUTHOR]

The valence and conduction band offsets at the interfaces between NiO/AlN, SiO2/AlN, Al2O3/AlN, and ITO/AlN heterointerfaces were determined via x-ray photoelectron spectroscopy using the standard Kraut technique. These represent systems that potentially would be used for p-n junctions, gate dielectrics, and improved Ohmic contacts to AlN, respectively. The band alignments at NiO/AlN interfaces are nested, type-I heterojunctions with a conduction band offset of −0.38 eV and a valence band offset of −1.89 eV. The SiO2/AlN interfaces are also nested gap, type-I alignment with a conduction band offset of 1.50 eV and a valence band offset of 0.63 eV. The Al2O3/AlN interfaces are type-II (staggered) heterojunctions with a conduction band offset of −0.47 eV and a valence band offset of 0.6 eV. Finally, the ITO/AlN interfaces are type-II (staggered) heterojunctions with conduction band offsets of −2.73 eV and valence band offsets of 0.06 eV. The use of a thin layer of ITO between a metal and the AlN is a potential approach for reducing contact resistance on power electronic devices, while SiO2 is an attractive candidate for surface passivation or gate dielectric formation on AlN. Given the band alignment of the Al2O3, it would only be useful as a passivation layer. Similarly, the use of NiO as a p-type layer to AlN does not have a favorable band alignment for efficient injection of holes into the AlN. [ABSTRACT FROM AUTHOR]

Functionalization of perovskite nanocrystal surfaces with thiocyanate anions presents a transformative approach to enhancing stability and photoluminescence quantum yield (PLQY) through surface defect passivation. This study investigates the role of thiocyanate ligands in modifying the optoelectronic properties of CsPbBr3 nanocrystals. We employed ultrafast two-dimensional infrared spectroscopy to investigate the nature of the dynamic interaction of thiocyanate ligands with nanocrystal surfaces, providing insights into the mechanisms underlying the observed increase in PLQY and stability. Our analysis reveals that the thiocyanate ligands efficiently passivate the surface defects, thereby enhancing the PLQY and the stability of the treated nanocrystals. The spectroscopic evidence supports a model where thiocyanate binds to under-coordinated lead atoms, contributing to a stable nanocrystal surface with enhanced optoelectronic performance. This ligand-induced passivation mechanism advances our understanding of surface chemistry's role in optimizing nanomaterials for solar cell and LED applications. [ABSTRACT FROM AUTHOR]

Chiral quantum dots (QDs) are promising materials applied in many areas, such as chiral molecular recognition and spin selective filter for charge transport, and can be prepared by facile ligand exchange approaches. However, ligand exchange leads to an increase in surface defects and reduces the efficiencies of radiative recombination and charge transport, which restricts further applications. Here, we investigate the light-induced photoluminescence (PL) enhancement in chiral L- and D-cysteine CdSe QD thin films, providing a strategy to increase the PL. The PL intensity of chiral CdSe QD films can be significantly enhanced over 100 times by continuous UV laser irradiation, indicating a strong passivation of surface defects upon laser irradiation. From the comparative measurements of the PL intensity evolutions in vacuum, dry oxygen, air, and humid nitrogen atmospheres, we conclude that the mechanism of PL enhancement is photo-induced surface passivation with the assistance of water molecules. [ABSTRACT FROM AUTHOR]

This study explored the interplay between the ligand–surface chemistry of colloidal CsPbBr3 nanowires (NWs) and their optical properties. The ligand equilibrium was probed using nuclear magnetic resonance spectroscopy, and by perturbing the equilibrium via dilution, the gradual removal of ligands from the CsPbBr3 surface was observed. This removal was correlated with an increase in the surface defect density, as suggested by a broadening of the photoluminescence (PL) spectrum, a decrease in the PL quantum yield (PLQY), and quenching of the PL decay. These results highlight similar surface binding between the traditional CsPbBr3 quantum dots and our NWs, thereby expanding the scope of well-established ligand chemistry to a relatively unexplored nanocrystal morphology. By controlling the dilution factor, it was revealed that CsPbBr3 NWs achieve a PLQY of 72% ± 2% and a relatively long average PL lifetime of 400 ± 10 ns, without relying on additional surface passivation techniques, such as ligand exchange. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive exploration of low interface trap density (Dit) in HfO2/Si0.73Ge0.27 metal-oxide semiconductor (MOS) capacitors achieved through sulfur passivation and post-deposition annealing (PDA). Our investigation revealed that devices subjected to sulfur passivation and PDA exhibit noteworthy reductions in Dit and hysteresis. Specifically, a low Dit value of 1.2 × 1011 eV−1 cm−2 has been achieved at Ei–0.1 eV for the SiGe MOS device. The observed enhancement in interface properties can be attributed to two key factors: the reduction of the GeOx concentration in the interfacial layer (IL) by sulfur passivation on the SiGe surface and the IL densification with stoichiometric oxygen during PDA. [ABSTRACT FROM AUTHOR]

All-inorganic CsPbI2Br inverted perovskite solar cells (PSCs) have drawn increasing attention because of their outstanding thermal stability and compatible process with tandem cells. However, relatively low open circuit voltage (Voc) has lagged their progress far behind theoretical limits. Herein, we introduce phenylmethylammonium iodide and 4-trifluoromethyl phenylmethylammonium iodide (CFPMAI) on the surface of a CsPbI2Br perovskite film and investigate their passivation effects. It is found that CFPMAI with a –CF3 substituent significantly decreases the trap density of the perovskite film by forming interactions with the under-coordinated Pb2+ ions and effectively suppresses the non-radiative recombination in the resulting PSC. In addition, CFPMAI surface passivation facilitates the optimization of energy-level alignment at the CsPbI2Br perovskite/[6,6]-phenyl C61 butyric acid methyl ester interface, resulting in improved charge extraction from the perovskite to the charge transport layer. Consequently, the optimized inverted CsPbI2Br device exhibits a markedly improved champion efficiency of 14.43% with a Voc of 1.12 V, a Jsc of 16.31 mA/cm2, and a fill factor of 79.02%, compared to the 10.92% (Voc of 0.95 V) efficiency of the control device. This study confirms the importance of substituent groups on surface passivation molecules for effective passivation of defects and optimization of energy levels, particularly for Voc improvement. [ABSTRACT FROM AUTHOR]

This article discusses a new fabrication process for colloidal silicon quantum dots (SiQDs) that allows for the tuning of their luminescence color from red to green. The process involves low-temperature thermal cracking of electrochemically prepared meso-porous silicon flakes in a mixture of 10-undecen-1-ol and aqueous hydrogen fluoride solution. The size of the SiQDs and their luminescence color can be controlled by adjusting the content of hydrogen fluoride. The article also explores the properties and potential applications of SiQDs in various fields, such as photovoltaic devices, light emitting devices, bio-imaging, and sensing. The document discusses the size-dependent radiative recombination processes of SiQDs, including factors that can affect their photoluminescence properties. It also explains the formation mechanisms of SiQDs and how they can result in different photoluminescence colors and peak wavelengths. The document concludes by discussing the relationship between the size of SiQDs and their photoluminescence peak energies, as well as the effect of surface passivation on quantum confinement. The article presents a novel method for producing SiQDs with tunable emission colors and suggests potential applications for SiQD devices. [Extracted from the article]

Modulation doping of silicon has great potential for miniaturization, surface passivation, and third generation photovoltaics (PV). At a modulation-doped silicon surface, we observe the formation of a 2D hole layer at the silicon surface at low temperatures by means of photoluminescence (PL) measurements. A line shape analysis of band–band and hot luminescence reveals the hole density (which is equal to the modulation-doped acceptor density). A high excitation intensity leads to a Fermi edge singularity of the band–band and hot PL emission. While the 2D layer can be characterized by the observed luminescence, the spectral region of twice the bandgap is fully dominated by emission from this surface layer, impeding the measurement of bulk hot luminescence, e.g., from Auger electrons or from nonthermalized carriers in a hot carrier PV device. [ABSTRACT FROM AUTHOR]

The acidic (pKa ≈ 1.5 – 2.5) and hygroscopic nature of poly(3,4-ethylene dioxythiophene) polystyrene sulfonate, used as a common hole-injection layer in optoelectronic devices, has a detrimental effect on device stability and is associated with well established device failure mechanisms. In this work, a process with a high green index hole-injection layer material (V 2 O 5) and low surface roughness (RMS roughness ≈ 1.3 nm) was developed for demonstrating a hybrid polymer–inorganic perovskite light-emitting diode. Test devices with the new hole-injection layer demonstrate nearly identical maximum current efficiencies (4.23 vs 4.19 cd/A), and luminous efficacies (2.99 vs 2.32 lm/W) when compared to a control device fabricated with the conventional hole-injection layer. Furthermore, the peak brightness was achieved at a current density one-third of the value for the control device. To examine the transport of holes in the above hole-injection layer, we carried out device simulations based on a physical charge control model, including defect-assisted tunneling for hole injection. Close agreement for current–voltage characteristics is observed. Experimentally measured mobility in the device and measured radiative lifetimes were found to be sufficient to achieve this agreement without resorting to the introduction of a sheet charge at the injection interface. Despite the use of a bulk-heterojunction device architecture, the model predicts high radiative recombination rates [ ≈ 5.6 × 10 22 /(cm 3 s)] in the emissive layer, consistent with the measured photophysical properties for the active film, suggesting effective passivation of non-radiative surface states. [ABSTRACT FROM AUTHOR]

Tuning of ferroic phases provides great opportunities for material functionalities, especially in two-dimensional materials. Here, a 4f rare-earth carbide Gd2C monolayer is predicted to be a ferromagnetic metal with large magnetization, inherited from its bulk property. Based on first-principles calculations, we propose a strategy that the surface passivation can effectively tune its ferroicity, namely, switching among ferromagnetic, antiferromagnetic, and ferroelectric phases. Metal–insulator transition also occurs accompanying these ferroic transitions. Our calculation also suggests that the magneto-optic Kerr effect and second harmonic generation are effective methods in monitoring these phase transitions. [ABSTRACT FROM AUTHOR]

It is a formidable challenge to find the minority carrier recombination lifetime in low-dimensional devices as low-dimensionality increases the surface recombination rate and often reduces the recombination lifetime to a scale of picoseconds. In this work, we demonstrated a simple but powerful method to quantitatively probe the minority carrier recombination lifetime in silicon nanowires or microwires by fitting the experimental photoresponses with our recently established analytical photoresponse principle of photoconductors. The nanowires were passivated with small molecules and Al2O3 to suppress surface recombination, which will increase the minority recombination lifetimes. As expected, the minority carrier recombination lifetime found by this approach increases by orders of magnitude. These wires were also made into PIN diodes, the leakage of which was reduced at least 1 order of magnitude after surface passivation by Al2O3. The minority recombination lifetime found from the leakage current of these devices is largely consistent with what we found from our analytical photoresponse principle. As a further step, we performed scanning photocurrent microscopy to find the minority diffusion length from which we found that the minority recombination lifetime is close to what we found from the analytical photoresponses. In short, this work validated that our analytical response principle is a reliable method to find the minority recombination lifetime in low-dimensional semiconductors. [ABSTRACT FROM AUTHOR]

In this work, the applicability of pulsed laser deposition (PLD) of transparent conductive oxides (TCOs) on high-quality ultra-thin poly-Si based passivating contacts is explored. Parasitic absorption caused by poly-Si layers can be minimized by reducing the poly-Si layer thickness. However, TCO deposition on poly-Si contacts, commonly by sputtering, results in severe deposition-induced damage and further aggravates the surface passivation for thinner poly-Si layers (<20 nm). Although a thermal treatment at elevated temperature (∼350 °C) can be used to partially repair the surface passivation quality, the contact resistivity severely increases due to the formation of a parasitic oxide layer at the poly-Si/ITO interface. Alternatively, we show that PLD TCOs can be used to mitigate the damage on ultra-thin (∼10 nm) poly-Si layers. Further improvement in poly-Si contact passivation can be achieved by increasing the deposition pressure while low contact resistivities (∼45 mΩ cm2) and good thermal stability (up to 350 °C) are achieved with a PLD indium-doped tin oxide (ITO) layer on high-quality ultra-thin poly-Si(n+) contacts. This allows for the application of a highly transparent front side contact by combining the excellent opto-electrical properties of a PLD ITO film with a 10 nm thin poly-Si contact. [ABSTRACT FROM AUTHOR]

This work reports a study of the passivation effects of different dielectric thin films deposited on monocrystalline CdTe/MgCdTe double heterostructures (DHs) using atomic layer deposition (ALD). Enhanced photoluminescence intensity was observed in all DHs with surface passivation, and increased photogenerated carrier lifetime was observed in DHs with HfO2, TiO2, Al2O3, and TiN passivated CdTe/MgCdTe DHs. These results have demonstrated effective suppression of the undesired surface recombination of CdTe/MgCdTe DHs by dielectric thin films deposited via ALD. [ABSTRACT FROM AUTHOR]

In this work, we studied the impact of environmental constituents such as oxygen (O2) and moisture on halide double perovskite (HDP) films. The transport measurements indicate that an increment in O2 concentration enhances the resistivity of a Cs2AgBiBr6 film by two orders of magnitude. The adsorption of O2 on the film's surface helps in passivation of defects (∼50% reduction in defect density on O2 exposure), which inhibits ion migration and results in an increased resistivity of the film. The process of adsorption and desorption of O2 on the film surface is found to be fully reversible. In contrast, the resistivity of double perovskite films decreases by an order of magnitude in the presence of moisture. This is attributed to the generation of free protons as a result of the dissociation of water molecules at the films' surface, hence exhibiting an increase in current under external bias. The HDP films possess high resistivity (for T < 100 °C) due to the desorption of physisorbed water layers from the surface, which gradually decreases with an increase in the operating temperature. This work demonstrates that O2 and moisture are a good combination for defect passivation in any HDPs, in general. [ABSTRACT FROM AUTHOR]

Green hydrogen (H2) production from solar water splitting necessitates photoelectrodes with superior photoelectrochemical (PEC) activity and durability. However, surface defects and photocorrosion instability—especially at high potentials—limit PEC performance and stability. Herein, the prototypical bismuth vanadate (BiVO4) photoanode is used to demonstrate a holistic approach to improve photocurrent density and long‐term stability. In this approach, high surface‐area nanostructuring of BiVO4 is combined with barium (Ba) doping with semi‐crystalline hafnium oxide (HfO2) surface passivation and single‐atom nickel platinum (NiPt) catalysts. The introduction of Ba2+ ions into BiVO4 increases the concentration of conductive V4+ ions or the ratio of V4+ ions to oxygen vacancies, avoiding V5+ dissolution during water oxidation. The semi‐crystalline HfO2, which serves as a passivation layer, prevents BiVO4 photocorrosion by suppressing harmful chemical reactions when holes are transferred to the electrolyte. The synergistic use of isolated single‐atom and Ni‐Pt coordination improves charge transfer at the photoanode/electrolyte interface, leading to enhanced PEC kinetics and stability. As a result, a photoelectrode is demonstrated with ≈6.5 mA cm−2 at 1.23 V versus a reversible hydrogen electrode (RHE) and continuous operation for 800 h with a negligible degradation rate. This work provides a promising approach to improve photoanodes for PEC H2 production. [ABSTRACT FROM AUTHOR]

Innovative research on metal‐oxide gas sensors involves nanostructuring and surface modification as key elements to tailor sensitivity and selectivity. This work addresses a ZnO nanowire‐based sensing device obtained by coupling a lithographically prepared substrate with hydrothermal ZnO growth, to align and interconnect the nanowires between two electrical contacts. Furthermore, conformal coating by atomic layer deposition technique allows functionalization of the surface of the nanowires with sub‐monolayers of Al2O3 and TiO2. A detailed analysis is carried out from a morphological and structural point of view with photoluminescence and Raman spectroscopy and electron microscopy. The material characterization results are analyzed in comparison with the functional characterization in gases toward reducing (NO2) and oxidizing (H2S) gases. Unparalleled sensing enhancement with Atomic Layer Deposition functionalization is obtained for NO2 detection. The passivation role of surface states is discussed combining information from experimental techniques with a proposed model. [ABSTRACT FROM AUTHOR]

Tin(ii) iodide (SnI2) faces significant challenges in photodetector applications, primarily due to its sensitivity to moisture and degradation over time. Achieving uniform, high‐quality films with low impurity and defect levels is also a challenge. Potential solutions include advanced deposition techniques to improve film quality and stability, surface passivation and encapsulation, doping and alloying. In this study, SnI2 thin films have been deposited for the first time using plasma enhanced chemical vapour deposition (PECVD) technique to the best of our knowledge. Process parameters like deposition pressure and RF‐power have been optimised via non‐intrusive in‐situ V−I probe impedance analyser. SnI2 thin films have been deposited on glass & transparent conducting oxide (TCO) and p‐Si wafer at various RF‐power to make SnI2/p‐Si heterojunction followed by metallization to make Ag/SnI2/p‐Si/Ag heterojunction photodetector. Characterization techniques like thin film thickness measurement, UV‐Vis‐NIR spectroscopy, Photoluminescence spectroscopy, glancing incidence x‐ray diffraction (GIXRD), SEM and I−V measurements were carried out to study its optical, structural and electronic properties. Fabricated devices, Ag/SnI2/p‐Si/Ag heterojunction photodiode exhibits best critical performance for the film deposited at 150 W having rectifying ratio of 6.9×104 at 1.0 V and photo‐sensitivity of 1.6×104 at 100 mW/cm2 light intensity. [ABSTRACT FROM AUTHOR]

Developing large‐scale monolithic perovskite/silicon tandem devices based on industrial Czochralski silicon wafers will likely have to adopt double‐side textured architecture, given their optical benefits and low manufacturing costs. However, the surface engineering strategies that are widely used in solution‐processed perovskites to regulate the interface properties are not directly applicable to micrometric textures. Here, we devise a surface passivation strategy by dynamic spray coating (DSC) fluorinated thiophenethylammonium ligands, combining the advantages of providing conformal coverage and suppressing phase conversion on textured surfaces. From the viewpoint of molecular engineering, theoretical calculation and experimental results demonstrate that introducing trifluoromethyl group provide more effective surface passivation through strong interaction and energy alignment by forming a dipole layer. Consequently, the DSC treatment of this bifunctional molecule enables the tandem cells based on industrial silicon wafers to achieve a certified stabilized power conversion efficiency of 30.89 %. In addition, encapsulated devices display excellent operational stability by retaining over 97 % of their initial performance after 600 h continuous illumination. [ABSTRACT FROM AUTHOR]

Hybrid Perovskite materials have gone through an astonishing development due to their unique optoelectronic behavior, leading to the creation of a wide range of synthetic strategies. As the materials’ surface is found to play a crucial role with respect to the properties, e.g. hydration, stability and carrier mobilities, considerable efforts have been made to optimize the surface through various approaches. Especially the passivation of the perovskite surface attracted a lot of attention in this field, often resulting in more complex, multi‐step synthetic processes. In this study, a simple one‐step aerosol‐assisted synthetic approach is presented to obtain thiocyanate (SCN) passivated single‐crystal MAPbBr3 microcrystals. To elucidate the role of the additive in the crystallization process, mixed (pseudo‐)halide precursors are systematically investigated. The as processed, passivated microcrystals exhibit enhanced stability and charge carrier lifetimes. Additionally, a decrease in surface photovoltage, attributed to the presence of the SCN additive, is observed. Furthermore, the aerosol process is further developed resulting in a novel binary system containing MAPbBr3‐SCN perovskite microcrystals and Au nanostructures. This system serves as a promising model for further investigations into potential interactions between plasmonic and semiconducting materials, with initial results indicating prolonged charge carrier lifetimes. [ABSTRACT FROM AUTHOR]

Inverted NiOx‐based perovskite solar cells (PSCs) exhibit considerable potential because of their low‐temperature processing and outstanding excellent stability, while is challenged by the carriers transfer at buried interface owing to the inherent low carrier mobility and abundant surface defects that directly deteriorates the overall device fill factor. Present work demonstrates a chemical linker with the capability of simultaneously grasping NiOx and perovskite crystals by forming a Ni−S−Pb bridge at buried interface to significantly boost the carriers transfer, based on a rationally selected molecule of 1,3‐dimethyl‐benzoimidazol‐2‐thione (NCS). The constructed buried interface not only reduces the pinholes and needle‐like residual PbI2 at the buried interface, but also deepens the work function and valence band maximum positions of NiOx, resulting in a smaller VBM offset between NiOx and perovskite film. Consequently, the modulated PSCs achieved a high fill factor up to 86.24 %, which is as far as we know the highest value in records of NiOx‐based inverted PSCs. The NCS custom‐tailored PSCs and minimodules (active area of 18 cm2) exhibited a champion efficiency of 25.05 % and 21.16 %, respectively. The unencapsulated devices remains over 90 % of their initial efficiency at maximum power point under continuous illumination for 1700 hours. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have garnered significant interest in recent years due to their high energy conversion efficiency, unique properties, low cost, and simplified fabrication process. However, the reactivity of these devices to external factors such as moisture, water, and UV light presents significant challenges for their commercial viability, potentially compromising their long-term stability and functionality. To overcome these limitations, researchers have focused on two primary strategies: surface passivation and additive engineering. Recent research developments have shown that surface passivation and additive engineering using conducting polymers (CPs), metal-organic framework materials (MOFs), and inorganic additives have significantly improved the operability of perovskite solar cells (PSCs). CPs form resilient interactions with perovskite grains, enhancing film stability through cross-link bonds. MOFs possess a unique network of functional holes that interact with multiple perovskite layers, maintaining morphology and improving interlayer charge transport. Inorganic additives suppress defects at grain boundaries, promoting the formation and growth of perovskite absorbers while providing mechanical protection. These advancements contribute to overcoming the reactivity limitations of PSCs and bring us closer to the commercialization of this technology. The review focuses on the advancements in similar materials, their passivation principles, and the resulting effects on PSC performance. Key aspects covered include the device structure, targeted defects, passivation processes, and synthesis outcomes. By providing a comprehensive overview, the review aims to assist in the selection and synthesis of novel materials. [ABSTRACT FROM AUTHOR]

In contrast to the conventional etching that makes nanoparticles rounder and our previous sharpening etching mode that causes serrated edges, here, we developed a new boring etching mode that targets the faces of Au nanoplates to make holes. The critical factors are the pre-incubation step with the ligand 2-mercapto-5-benzimidazolecarboxylic acid (MBIA) and the subsequent removal of excess ligands in the solution. Thus, etching is focused onto the few sites with initial loss of ligands, which cannot be quickly replaced. The choice of ligand MBIA is also of importance, as it carries negative charge and repels each other. Its inability of forming a dense layer probably plays a critical role in the site-selectivity for faces, because ligands at the higher curvature edges and corners are expected to have less repulsion. The etching results from the comproportionation reaction between Au3+ and Au0 in the nanoplates, where Br− coordination to Au and the extra stabilization from cetyltrimethylammonium bromide (CTAB) are essential. We believe that the ability of boring holes is an important tool for future synthetic designs. [ABSTRACT FROM AUTHOR]

With the improvement of surface passivation, bulk recombination is becoming an indispensable and decisive factor to assess the theoretical limiting efficiency (ηlim) of crystalline silicon (c‐Si) solar cells. In simultaneous consideration of surface and bulk recombination, a modified model of ηlim evaluation is developed. Surface recombination is directly depicted with contact selectivity while bulk recombination is revised on the aspects of ideality factor and wafer thickness. The ηlim of the double‐side silicon heterojunction (SHJ) and double‐side tunneling‐oxide passivating contact (TOPCon) solar cells are numerically simulated using the new model as 28.99% and 29.19%, respectively. However, the ηlim of single‐side TOPCon solar cells, the more practicable scenario, is only 27.79%. Besides, the ηlim of the double‐side SHJ solar cells would exceed the double‐side TOPCon solar cells if the recombination parameter of the non‐contacted area is higher than 0.6 fA/cm2, instead of perfect passivation. Our results are instructive in accurately assessing efficiency potential and accordingly optimizing design strategies of c‐Si solar cells. [ABSTRACT FROM AUTHOR]

The ligand passivation is considered an attractive strategy to prepare high‐quality perovskite nanocrystals (PNCs) with improved photophysical features in polar media. However, the long‐term stabilization of PNCs in these environments is still challenging, being pivotal to understanding the protection mechanism given by prominent surface ligands and avoiding material deterioration in polar solvents. In this work, how the nature of diverse alkylammonium bromides used during surface passivation influences the photophysical properties and quality of CsPbX3 PNCs fully dispersed in alcohol environments, exhibiting stability up to 10 months are investigated. By adding didodecyldimethylammonium benzyldodecyldimethylammonium and tetrabutylammonium bromides (DDAB, BDAB, and TBAB, respectively), DDAB and BDAB promote a suitable and partial surface coverage are observed, respectively, suppressing defect sites in the nanocrystals. Conversely, TBAB shows poor surface protection, decreasing the PL features of PNCs. The presence of DDAB and BDAB favors the fabrication of color converters, and efficient light‐emitting diodes (LEDs) with external quantum efficiencies (EQE) of ≈23%. Interestingly, significant device stability with BDAB capping shows an LED half‐life of 20‐fold longer than for DDAB. This contribution offers a promising approach for preparing highly luminescent and stable alcohol‐dispersed PNCs, useful for fabricating efficient optoelectronic devices. [ABSTRACT FROM AUTHOR]

Herein, p‐type flexible and transparent electrodes of Cu2–xSe are produced at different conversion times at 20, 25, and 30 s of polyester/Cu thin films via chemical bath deposition. To study the charge transport properties across the Cu2–xSe layer, the organic light‐emitting diodes (OLEDs) are produced according to the following configuration: polyester/Cu2–xSe/poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate)/poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene]/aluminum (polyester/Cu2–xSe/PEDOT:PSS/MEH‐PPV/Al), resulting in a direct tunneling in the transport of holes. The control of the barrier's energy between the Cu2–xSe electrode and the MEH‐PPV polymer allows it to tune selectively of the OLED’ charge transport mechanism. The morphological analysis of the Cu2–xSe electrode, carried out using atomic force microscopy, as well as the temperature dependence of the current–voltage measurements in the OLED (50–300 K) shows the ideal deposition time in the chemical bath. In contrast, impedance spectroscopy results confirm the inexistence of the Cu2–xSe/PEDOT:PSS interface using 30 s to Cu2–xSe synthesis. As a result, the control of the injection mechanism of charges can be obtained by reducing the barrier energy to hole transport during the synthesis process of the Cu2–xSe layer via chemical bath deposition, thus simplifying and reducing the costs of the device's processing. [ABSTRACT FROM AUTHOR]

Fluorescent carbon nanoparticles, also known as carbon quantum dots (CQDs), have piqued the interest of researchers due to their numerous uses in chemical sensing, biomedical imaging, nanotechnology, photovoltaics, LEDs, and hydrogen generation. Aside from their optical brilliance, CQDs have benefits like low toxicity, environmental friendliness, cost‐effectiveness, and ease of manufacture, with adjustable properties via surface passivation and functionalization. This review article goes over CQDs in‐depth, addressing synthesis advances, benefits, limits, various synthesis processes, and prospective hydrogen generation applications. While CQDs have photocatalytic properties, they confront a few challenges, including low quantum yields, spectrum limitations, photostability limitations, limited catalytic activity, scaling difficulties, and environmental issues. Thorough research is required to use CQDs in sustainable hydrogen generation. Despite obstacles, CQD research remains appealing, with transformational promise for a cleaner and more sustainable energy future through controlled synthesis approaches displaying CQDs' many uses. [ABSTRACT FROM AUTHOR]

This study presents the Br‐rich in situ synthesis of blue‐emitting 2D CsPbBr3 nanoplatelets (NPLs) with various Br/Pb ratios using ZnBr2 as a Br precursor to enhance Br ion adsorption significantly. This leads to effective passivation of surface defects, particularly Pb−Br bonds, by increasing the positive charge density around Pb atoms, thus creating a stable bonding environment and reducing defect formation. Consequently, the photoluminescence quantum yield (PLQY) improves from 31.15% for a Br/Pb ratio of 2 to 87.2% for a ratio of 6. NPLs with a Br/Pb ratio of 6 also exhibit longer lifetimes (16.69 ns) and slower bleach recovery dynamics, indicating fewer non‐radiative recombination pathways and effective exciton dynamics. Additionally, NPLs with the Br/Pb ratio of 6 demonstrated better thermal stability, with an activation energy of 124.3 meV, indicating stronger exciton binding. These NPLs also exhibited enhanced stability, with UV tolerance at 43.9% and water resistance at 23.8%, making them suitable for displays and lighting. Furthermore, Br‐passivated CsPbBr3 NPLs are used as blue emitters in prototype white LEDs, achieving a wide color gamut, 126.6% of the National Television Standards Committee and 94.5% of Rec. 2020, demonstrating their potential for high‐quality lighting and advanced display technologies. [ABSTRACT FROM AUTHOR]

A highly transparent passivating contact (TPC) used for high‐efficiency crystalline silicon (c‐Si) solar cells should meet several key criteria: high optical transparency, excellent c‐Si surface passivation, low contact resistivity, and a low‐temperature fabrication process suitable for device integration. Here, a simple TPC is developed structure consisting of a silicon oxide (SiOx) tunneling passivating layer and an aluminum doped zinc oxide (AZO) electron‐selective transporting layer (SiOx/AZO). This TPC demonstrated remarkable passivation quality with a low contact recombination current density of below 2.2 fA cm−2, an implied open‐circuit voltage of close to 740 mV and a contact resistivity below 20 mΩ·cm2 when contact with lightly doped n‐type c‐Si. This excellent passivation performance can be attributed to improved interfacial hydrogen chemical passivation and the field‐effect passivation induced by the highly Al‐doped ZnO film. Demonstrated n‐type c‐Si solar cells using full‐area SiOx/AZO rear contacts achieved a significant efficiency of 23.17%. Further power loss analysis based on numerical simulations outlines the pathway to achieving efficiencies exceeding 26%. [ABSTRACT FROM AUTHOR]

The presence of a high density of defects at the perovskite/electron transport layer (ETL) interface results in significant nonradiative recombination losses, thus impeding the efficiency enhancement of perovskite/silicon tandem solar cells (TSCs). In this investigation, a metallocene‐based molecule, cobalt (III) dichlorophene hexafluorophosphate (CcPF6), is employed for perovskite surface passivation. To maximize its efficacy, the molecule is dissolved in a mixed solvent of acetonitrile and chlorobenzene, leading to the reconstruction of the perovskite surface and effective passivation of surface defects. This modification strategy substantially enhances the overall efficiency of perovskite/silicon tandem solar cells by mitigating the issue of low fill factor resulting from non‐uniform coating of the top perovskite layer on the textured silicon bottom cell. Leveraging a double‐sided textured silicon heterojunction (HJT) bottom cell, a certified power conversion efficiency (PCE) of 30.43% for a monolithic perovskite/silicon TSC (1.00 cm2) is achieved, featuring an open‐circuit voltage (Voc) of 1.93 V and a fill factor (FF) of 78.43%. After storage in the drying cabinet (5% humidity at 20 °C) for 1000 h, the device retains 94.27% of its initial performance. [ABSTRACT FROM AUTHOR]

Tin oxide (SnO2) with high conductivity and excellent photostability has been considered as one of the most promising materials for efficient electron transport layer (ETL) in perovskite solar cells (PSCs). Among them, SnO2 nanoparticles (NPs) dispersions have been extensively utilized due to their facile film formation. However, the inherent defects and agglomeration issues of SnO2 NPs, as well as the limited tunability and instability of the post‐treatment process for surface/interface engineering strategy, still hinder its further applications. Herein, a ligand‐management strategy implemented during the in situ synthesis of NPs that can effectively achieve uniform modification of NPs is proposed. During the synthesis of SnO2 NPs, the grafting reaction between diethyl 2‐chloromalonate (DCMA) and the surface of SnO2 NPs is completed. Compared with the post‐treatment process, this intrinsic DCMA‐passivated SnO2 (DCMA‐SnO2) effectively reduces the trap state density at the interface between perovskite and ETL while enhancing surface chemical stability. Consequently, PSCs based on DCMA‐SnO2 achieve a champion PCE of 25.39% for small cells (active area of 0.0655 cm2) and 20.61% for solar modules (active area of 23.25 cm2), demonstrating excellent shelf‐life/light soaking stability (advanced level of ISOS stability protocols). This ligand‐management strategy exhibits significant application potential in preparing high‐efficiency large‐area PSCs. [ABSTRACT FROM AUTHOR]

The electrochemical corrosion behaviors of Ti3SiC2/Cu composites in harsh media including dilute HNO3 and concentrated H2SO4 were studied in detail and the related corrosion mechanisms were explored. Under open-circuit potential, the corrosion resistance of Ti3SiC2/Cu in dilute HNO3 was worse than that in concentrated H2SO4. In dilute HNO3, Ti3SiC2/Cu exhibited a typical passivation character with a narrow passivation interval. During the corrosion process, the dissolution of Cu-Si compounds resulted in the destruction of the passivation layer on the surface. Additionally, with the increasing of the potentials, the oxidation of Cu and Si atoms led to the generation of the oxide film again on the surface. In concentrated H2SO4, the Ti3SiC2/Cu composite was covered by a double-layered passivation layer, which was composed of an internal layer of TiO2 and an external layer of Cu2O and SiO2. This was because Cu diffused into the surface and was oxidized into Cu2O, which formed a denser oxidized film with SiO2. In addition, it was found that Ti3SiC2/Cu has better corrosion resistance in concentrated H2SO4. [ABSTRACT FROM AUTHOR]

The stress corrosion behavior of Ti‐6Al‐3Nb‐2Zr‐1Mo (Ti6321, in wt%) alloy in seawater with different dissolved oxygen (DO) concentrations was investigated using X‐ray photoelectron spectroscopy, energy dispersive spectrometer, electrochemical measurements, and other advanced methodologies. The results indicate that when the DO concentration in seawater is insufficient, the passivation film will preferentially form on the α‐phase surface. Meanwhile, insufficient DO concentration leads to incomplete oxidation of the surface passivation film, resulting in an increase in surface defects. Hydrogen produced by reactions at crack tips is more likely to enter the surface of the titanium alloy through these defects, and under the influence of HEDE and HELP mechanisms, promote crack propagation. [ABSTRACT FROM AUTHOR]

As we know, the ligands on the surface of core/shell structured quantum dots (QDs) play an important role. They not only bind with metal ions to passivate surface defects but also have a great influence on colloidal stability. All-organic or all-inorganic ligands afford QDs with some disadvantages such as low conductivity, poor dispersibility and undesirable stability. By combining with the advantages of organic and inorganic ligands, herein, we achieve an organic/inorganic hybrid surface passivation through exchanging partial oleic acid ligands with chlorine ions (Cl−), affording QD with a core/shell structure of CdZnSe/ZnSe/ZnS/OACl. It exhibits an excellent nanostructure with a mean size of around 11.6 nm. According to X-ray photoelectron spectroscopy (XPS) spectra, around 30% oleid acid ligands are removed by Cl−, resulting in the hybrid surface passivation. The CdZnSe/ZnSe/ZnS/OACl QD exhibit an efficient green emission at the wavelength of around 535 nm with a quantum yield of over 90%. The QD light-emitting diode (QLED) based on CdZnSe/ZnSe/ZnS/OACl exhibits a peak EQE of 15.6% and a brightness of over 1.1 × 105 cd m−2 at 6 V, corresponding to an efficient green emitting device. Therefore, we believe that the hybrid surface passivation could provid a reliable avenue to efficient QD materials. [ABSTRACT FROM AUTHOR]

Colloidal quantum dot (CQD) based infrared (IR) photodetectors offer facile wavelength tunability in the IR and low‐cost fabrication. However, owing to their large surface areas, CQDs intrinsically have significant surface traps critically affecting the speed of CQD photodetectors, typically mediated through tedious surface passivation efforts. In this report, an alternative strategy involving coupling of near‐IR photoactive lead sulfide CQDs with a thermally evaporated amorphous selenium (a‐Se) hole transport layer is proposed. By separating the detector into a photon absorbing CQD region and a charge transport a‐Se region, the study takes advantage of the extremely low noise, predominantly hole‐only transport process in a‐Se. A high 3 dB bandwidth of 2.5 MHz and a competitive specific detectivity of 2.5 × 1011 Jones at room temperature are demonstrated at 980 nm. This report serves as a first demonstration of strong coupling between an IR active CQD absorber and a‐Se, which paves the path to obtain fast and highly photoresponsive IR photodetection in the future. [ABSTRACT FROM AUTHOR]

The application of all inorganic halide perovskite quantum dots (PQDs) in the field of optoelectronic devices has made exciting progress. However, the preparation of CsPbX3·PQDs with high water stability is still a great challenge. In this article, the direct synthesis of CsPbCl3·PQDs in water using 4-chlorobutyric acid (CBA) and oleamine (OLA) as surface ligands was proposed for the first time. Transmission electron microscopy spectra show that the QDs synthesized in water have good crystallinity and monodispersity. At the same time, CBA-CsPbCl3·PQDs synthesized by this method continuously emitted light in water for more than 400 h. In contrast, OA-CsPbCl3·PQDs were almost completely quenched after only 20 min of mixing with water. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and hydrogen spectroscopy nuclear magnetic resonance were used to verify the passivation effect of CBA on the surface of QDs. The carboxyl ligands provided by CBA form a stable hydrophobic shell on the surface of CsPbCl3·PQDs, which makes CsPbCl3·PQDs have excellent water stability. In this study, CsPbCl3·PQDs with excellent water stability were synthesized with CBA/OLA as the surface ligand for the first time, which provides an effective way to explore perovskite light-emitting diodes with good water stability. [ABSTRACT FROM AUTHOR]

Hafnium oxide (HfOx) films grown by atomic layer deposition (ALD) have recently been demonstrated to provide high‐quality silicon surface passivation. Reports have suggested that changing the composition of the hafnium‐containing precursor can enable films of both charge polarities to be produced. Herein, the passivation quality of hafnium oxide grown with metal amide precursors and a tetrakis(ethylmethylamido)hafnium (TEMAHf) precursor is examined, considering film charge polarity, chemical‐ and field‐based passivation effects, and film crystallinity. Throughout, the properties of TEMAHf‐HfOx are benchmarked against that of hafnium oxide grown with a tetrakis(dimethylamido)hafnium precursor. It is found that precursor choice has no influence on the fixed negative charge polarity (of order −1012 q cm−2) of HfOx films grown via plasma‐enhanced ALD. TEMAHf‐HfOx passivation is influenced by post‐deposition annealing temperature and can passivate with a surface recombination velocity ≤3 cm s−1 on n‐type silicon, compared to surface recombination velocities ≤11 cm s−1 for TDMAHf‐HfOx of a similar thickness. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have demonstrated remarkable progress in performance in recent years, which has placed perovskite materials as the leading promising materials for future renewable energy applications. The solvent additive technique in perovskite composition is a simple but effective process used to improve the surface quality of the perovskite layers and to improve the performance and charge transport processes essential to the functions of PSCs. These additives can have a considerable effect on the topography, crystallinity, and surface properties of the perovskite active layer, ultimately influencing the stability of the PSCs. A "two-step spin coating" deposition method to make PSCs in ambient air laboratory conditions was employed. Acetonitrile (ACN) was conventionally utilized as a chemical additive to enhance the performance of PSCs. In this study, our film properties exhibited that the incorporation of ACN in the triple cation perovskite precursor led to the passivation of surface defects and a noticeable increase in the size of the crystal grains of the perovskite films, which led to enhanced stability of devices. The efficiency achieved for PSCs prepared with 10% ACN was 15.35%, which is 30% higher than devices prepared without ACN. In addition, devices prepared with ACN have shown a lower hysteresis index and more stable behavior compared to devices prepared without ACN. This work presents an easy, low-cost method for the fabrication of high performance PSCs prepared under ambient air laboratory conditions. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid perovskite quantum dots (QDs) have garnered significant research interest owing to their unique structure and optoelectronic properties. However, their poor optical performance in ambient air remains a significant limitation, hindering their advancement and practical applications. Herein, three amino acids (valine, threonine and cysteine) were chosen as surface ligands to successfully prepare highly luminescent CH3NH3PbBr3 (MAPbBr3) QDs. The morphology and XRD results suggest that the inclusion of the amino acid ligands enhances the octahedral structure of the QD solutions. Moreover, the observed blue-shifted phenomenon in the photoluminescence (PL) aligns closely with the blue-shifted phenomenon observed in the ultraviolet–visible (UV-Vis) absorption spectra, attributed to the quantum confinement effect. The time-resolved spectra indicated that the introduction of the amino acid ligands successfully suppressed non-radiative recombination, consequently extending the fluorescence lifetime of the MAPbBr3 QDs. The photoluminescence quantum yields (PLQYs) of the amino acid-treated MAPbBr3 QDs are increased by 94.8%. The color rendering index (CRI) of the produced white light-emitting diode (WLED) is 85.3, with a correlated color temperature (CCT) of 5453 K. Our study presents a novel approach to enhancing the performance of perovskite QDs by employing specially designed surface ligands for surface passivation. [ABSTRACT FROM AUTHOR]

Hexavalent chromium (Cr(VI) contamination in water and wastewater can be treated by reduction of Cr (VI) to Cr(III) with reductants. In this study, the practicality of using FeOx crystals obtained from wastewater was evaluated by studying their reaction with Cr(VI). Cr(VI) was completely removed within 1 to 8 hours of reaction with FeOx, depending on the initial concentration up to 1.9 mM tested. After complete removal of Cr(VI) by FeOx, 22%-38% of the original concentration of Cr(VI) was converted to Cr(III) in the solution, indicating the remaining 62%-78% of the Cr(VI) was associated with the FeOx surface. Cr(VI) was removed by FeOx via reduction to Cr(III) and adsorption/precipitation on the FeOx surface. At pH 3, Cr(VI) was completely removed by FeOx within 20 minutes. Around 20% of the initially added Cr(VI) remained in the solution as Cr(III), while approximately 80% was removed from the solution. At pH 7, roughly 30% of the Cr(VI) was reduced to Cr(III) and the remaining 40% appeared to be in the solid phase after 2-hour reaction. At pH 10, approximately 40% of the Cr(VI) was removed, but Cr(III) was not observed in the solution. The Cr(VI) removal by FeOx is mainly achieved by the reduction of Cr(VI) to Cr(III) under acidic to neutral conditions, and by the adsorption of Cr(VI) onto the solid phase under alkaline conditions. The reduction of Cr(VI) occurred mainly through the reaction with ferrous iron of FeOx, which was enhanced by oxalate of FeOx, forming a soluble Fe(III)-oxalate complex with Fe(III) and reducing the passivation of the FeOx surface. Our study indicates that FeOx is effective at removing Cr(VI) at various concentrations and pH levels. [ABSTRACT FROM AUTHOR]

Non-conjugated polymer-derived functional nanocomposites are one of the important ways to develop multifunctional hybrids. By increasing the degree of crosslinking, their photophysical properties can be improved. PbS is a class of narrow bandgap infrared active materials. To avoid aggregation and passivation of the surface defects of PbS nanomaterials, a large number of organic and inorganic ligands are usually used. In this study, PbS/C composite nanosheets were synthesized with Pb2+ ion-crosslinked sodium alginate gel by one-pot carbonization. The resulting nanosheets were coated on untreated A4 printing paper, and the electrodes were the graphite electrodes with 5B pencil drawings. The photocurrent signals of the products were measured using typical 650, 808, 980, and 1064 nm light sources. The results showed that the photocurrent switching signals were effectively extracted in the visible and near-infrared regions, which was attributed to the mutual passivation of defects during the in situ preparation of PbS and carbon nanomaterials. At the same time, the resulting nanocomposite exhibited electrical switching responses to the applied strain to a certain extent. The photophysical and defect passivation mechanisms were discussed based on the aggregation state of the carbon hybrid and the interfacial electron interaction. This material would have potential applications in broadband flexible photodetectors, tentacle sensors, or light harvesting interdisciplinary areas. This study provided a facile approach to prepare a low-cost hybrid with external stimulus response and multifunctionality. These results show that the interfacial charge transfer is the direct experimental evidence of interfacial interaction, and the regulation of interfacial interaction can improve the physical and chemical properties of nanocomposites, which can meet the interdisciplinary application. The interdisciplinary and application of more non-conjugated polymer systems in some frontier areas will be expanded upon. [ABSTRACT FROM AUTHOR]

Halide perovskite single crystals (SCs) have attracted much attention for their application in high‐performance x‐ray detectors owing to their desirable properties, including low defect density, high mobility–lifetime product (μτ), and long carrier diffusion length. However, suppressing the inherent defects in perovskites and overcoming the ion migration primarily caused by these defects remains a challenge. This study proposes a facile process for dipping Cs0.05FA0.9MA0.05PbI3 SCs synthesized by a solution‐based inverse temperature crystallization method into a 2‐phenylethylammonium iodide (PEAI) solution to reduce the number of defects, inhibit ion migration, and increase x‐ray sensitivity. Compared to conventional spin coating, this simple dipping process forms a two‐dimensional PEA2PbI4 layer on all SC surfaces without further treatment, effectively passivating all surfaces of the inherently defective SCs and minimizing ion migration. As a result, the PEAI‐treated perovskite SC‐based x‐ray detector achieves a record x‐ray sensitivity of 1.3 × 105 μC Gyair−1 cm−2 with a bias voltage of 30 V at realistic clinical dose rates of 1–5 mGy s−1 (peak potential of 110 kVp), which is 6 times more sensitive than an untreated SC‐based detector and 3 orders of magnitude more sensitive than a commercial α‐Se‐based detector. Furthermore, the PEAI‐treated‐perovskite SC‐based x‐ray detector exhibits a low detection limit (73 nGy s−1), improved x‐ray response, and clear x‐ray images by a scanning method, highlighting the effectiveness of the PEAI dipping approach for fabricating next‐generation x‐ray detectors. [ABSTRACT FROM AUTHOR]

The inherent defects (lead iodide inversion and iodine vacancy) in perovskites cause non‐radiative recombination and there is also ion migration, decreasing the efficiency and stability of perovskite devices. Eliminating these inherent defects is critical for achieving high‐efficiency perovskite solar cells. Herein, an organic molecule with multiple active sites (4,7‐bromo‐5,6‐fluoro‐2,1,3‐phenylpropyl thiadiazole, M4) is introduced to modify the upper interface of perovskites. When M4 interacts with the perovskite surface, the active bromine (Br) site interacts with lead (Pb) at the surface to repair iodine atomic vacancy defects. The fluorine (F) site of M4 interacts with Pb to correct octahedral crystal lattice distortions and eliminate PbI defects. Additionally, sulfur–iodine (S–I) interactions reduce I–I dimerization and eliminate IPb defects. It is also calculated that the energy level of M4 aligns with the band gap, promoting charge transfer. As a result, the perovskite devices achieve an efficiency of 25.1%, a stabilized power output (SPO) of 25.0%, a voltage of 1.19 V, and a fill factor of 85.2%. The device retains 95% of its initial efficiency after 2000 h of ageing in a nitrogen atmosphere. Thus, multi‐point cooperative passivation of surface defects provides an effective method to improve the efficiency and stability of perovskite solar cells. [ABSTRACT FROM AUTHOR]

Although there are significant advancements in device‐level artificial tactile and visual perception systems based on in‐sensor computing paradigms, the development of hardware‐implemented neuromorphic olfactory system is still in its early stages. One of the primary challenges in this field is that most of the gas sensors lack the capability to fuse the sensing and computing functions in a single sensor. Through surface passivation and interface engineering, this work introduces a device‐level artificial olfactory system utilizing array of PCBM‐MAPbI3 heterostructure transistors. Noteworthly, the formation of metastable intermediate phase NH3PbI3•MA can occur at room temperature and can be used to store gas sensory information. Both gas pulse and electrical pulse can dynamically modulate the amount of this intermediate phase, and then change the channel conductance (weight), realizing the fusion of the sensing and synaptic functions in single device. Based on these excellent properties, the spatiotemporal information of gas diffusion can be encoded and processed simultaneously. As a result, an in‐sensor olfactory perception system is successfully demonstrated based on 5 × 5 PCBM‐MAPbI3 heterostructure transistor array, which can be used for detecting the distance and direction of the hazardous gas. This work paves the way for future application of real‐time and data‐intensive machine‐olfactory system. [ABSTRACT FROM AUTHOR]

The photovoltaic performance of inverted perovskite solar cells (PSCs) is often hindered by trap‐induced non‐radiative recombination and photochemical degradation occurring at the upper interfaces and the grain boundaries of perovskite films. Herein, ortho‐, meta‐, and para‐isomers of fluorophenylethylammonium iodine (F‐PEAI) organic spacer molecules are evaluated for the construction of perovskite quantum wells (2D or quasi‐2D, PQWs) to encapsulate 3D perovskites. Among the three variants, p‐F‐PEAI leads to the most symmetric charge distribution and the weakest steric hindrance which resulting in reinforced interactions with PbI2 and perovskite, the enhanced out‐of‐plane orientation is confirmed by Grazing incidence wide‐angle X‐ray scattering (GIWAXS) results. Density functional theory and crystal orbital Hamilton population (COHP) calculations further confirm that p‐F‐PEAI engages most strongly with the perovskite structure. Moreover, transmission electron microscopy (TEM) characterization is used to illustrate that p‐F‐PEAI‐assisted 2D PQWs effectively passivate both the grain boundaries and surfaces of perovskites. This configuration facilitates effective surface passivation, improves charge carrier transport, and significantly suppresses non‐radiative recombination. The resultant inverted PSCs achieve an excellent power conversion efficiency (PCE) of 25.03% with a fill factor (FF) of 85.11%. The unencapsulated devices exhibit enhanced long‐term stability under ambient environments and continuous light illumination. [ABSTRACT FROM AUTHOR]

Conventional silicon junction detectors encounter significant carrier recombination within the heavily doped p+ and n+ layers, as well as beneath the metal contact regions, creating the so-called "dead layers", especially on the detector side. In this study, we present the tunnel oxide passivating contact with doped polysilicon on oxide, which demonstrates exceptional surface passivation and carrier selectivity. The key innovation lies in an ultra-thin (~ 1.5 nm) interfacial oxide layer that facilitates efficient majority carrier transportation via tunneling while effectively block minority carriers. Remarkably low saturation current densities, ranging from 5 to 10 fA/cm2 even with the metal contact, underscore the superiority of both n-type and p-type tunnel oxide passivating contacts. In contrast, conventional p–n junction or high-low junction exhibit saturation current densities ranging from 10 to 90 fA/cm2 in the studied p+ and n+ layers with surface passivation schemes due to Auger recombination and surface recombination, and 1000–6000 fA/cm2 with metal contacts due to intense metal-induced recombination at the interface. These findings indicate the potential and superiority of implementing n-type tunnel oxide passivating contact on the detector side and p-type contact on the back side for advanced silicon radiation detectors. This approach would enable thorough collection of generated charge carriers along the track of incident ionizing radiation particles, leading to improved energy resolution and reduced noise levels. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the underlying physics limiting the temperature stability and performance of non-surface passivated Al0.34Ga0.66N/GaN Hall effect sensors, including contacts, under atmospheric conditions. The results obtained from analyzing the microstructural evolution in the Al0.34Ga0.66N/GaN Hall sensor heterostructure were found to correlate with the electrical performance of the Hall effect sensor. High-resolution x-ray photoelectron spectroscopy studies revealed the signature of surface oxidation in the GaN cap layer, as well as a slight out-diffusion of "Al" from the AlGaN barrier layer. To prevent the formation of a bumpy surface morphology at the Ohmic contact, we investigated the impact of "Pt" top Ohmic contacts. The application of a top "Pt" contact stack resulted in a smooth Ohmic contact surface and provided evidence that the bumpy surface morphology in Au-based Ohmic contacts is due to the formation of an Al-Au viscous alloy during rapid thermal annealing. In the early stages of thermal aging, the small drop in contact resistivity stabilized with subsequent thermal aging past the initial 550 h at 200 °C. The outcome is that the Al0.34Ga0.66N/GaN Hall effect sensors, even without surface passivation, exhibited a stable response to applied magnetic fields with no sign of significant degradation after 2800 h of thermal aging at 200 °C under atmospheric conditions. This observed stability in the Hall sensor without surface passivation can be attributed to a self-imposed surface oxidation of the cap layer during the early stages of aging, which serves as a protective layer for the device during subsequent extended periods of thermal aging at 200 °C. [ABSTRACT FROM AUTHOR]

The emission of cyan light (470–500 nm), an essential component of the visible light spectrum, plays a crucial role in lighting, display, and light communication. CsPbBr3 quantum dots (QDs) have shown excellent performance in the green spectral regions, with high color purity, efficiency, and brightness. In order to shift the emission wavelength to the cyan, mixed-halide compositions and quantum-confinement engineering have been employed. Unfortunately, mixed-halide perovskites exhibit undesirable phase separation during optical and electrical excitations, leading to spectral instability. Quantum confinement in pure-halide QDs requires synthetic protocols that involve high loading of long-chain insulating ligands. In this study, we report color-stable cyan CsPbBr3 quantum dots (C-PQDs) by surface passivation via incorporating Zn2+ cations. The incorporation of ZnBr2 into the precursor solution facilitates Zn2+ and Br− substitution into the QDs surface/subsurface layers to induce passivation of existing Pb2+ and Br− vacancies and increase the photoluminescence quantum yield from 53.6% to 96.4% at 480 nm. Moreover, after storage under ambient conditions for 30 days or exposure to ultraviolet light for 60 minutes or heating at 333 K, the PL intensity of ZnBr2-treated C-PQDs only shows a minimal decrease. Furthermore, white and cyan light-emitting diodes (LEDs) are successfully constructed, suggesting that the proposed ZnBr2-treated strategy can promote the development of perovskite materials for a wider range of optoelectronic applications. [ABSTRACT FROM AUTHOR]