Nanocrystalline NiO Research Articles

Increase the efficiency of lead sulfide colloidal quantum dots solar cells by incorporating In2O3 and NiO interlayers

Substantial advancements have been made in PbS colloidal quantum dot solar cells (CQDSCs) by focusing on device architecture, manipulating band alignment, and refining the surface chemistry of colloidal quantum dots (CQDs). Nevertheless, creating an incredibly stable and efficient solar cell remains a challenging problem for researchers in this field. This study reveals that the efficiency of PbS CQDSCs can be improved by incorporating ultrathin In2O3 (between ITO electrode & indium-doped zinc oxide ETL) and NiO (between PbS-EDT HTL and Au electrode) nanocrystalline interlayers. The enhanced power conversion efficiency (PCE), which increases from 11.5 % to 13.6 %, is attributed to the improved surface smoothness and well-matched energy bandgap. Furthermore, following a heating period of 90 min at a temperature of 80 °C and 50 days of storage in the air, the solar cells containing these interlayers retained 98 % and 99 % of their initial efficiency, respectively. In distinction, the control device without these interlayers maintained only 85 % and 91 % of their initial efficiency under identical testing environments.

Unveiling the catalytic performance of unique core-fibrous shell silica-lanthanum oxide with different nickel loadings for dry reforming of methane

The dry reforming of methane (DRM) stands as a remarkable process for the conversion of methane and carbon dioxide into syngas (H2/CO). In this study, mesoporous fibrous silica lanthanum oxide-supported nickel catalysts (NSLF-x) with various nickel loadings (3 to 15 wt%) were efficiently fabricated using the microemulsion and impregnation approaches, respectively, to conduct DRM. The results obtained from FESEM and TEM revealed the presence of a unique core-fibrous shell-structured morphology of silica lanthanum oxide support (SLF). Furthermore, XRD and SEM-EDS analyses indicated that the structural integrity of SLF remained consistent regardless of the amount of Ni loading, while the size of NiO nanocrystalline varied with the quantity of Ni loading. Notably, H2-TPR analysis emphasized that the NSLF-15 catalyst exhibited the strongest metal-support interaction among the catalysts. Due to this reason, it exhibited outstanding catalytic activity and stability in terms of CO2 conversion (86.7 %), CH4 conversion (87 %), and a high H2/CO ratio at 750 °C, demonstrating high thermal stability after 28 h without any signs of deactivation. The superior catalytic performance of NSLF-15 catalysts, along with their ability to activate CH4 and CO2, can be attributed to the synergistic effects resulting from the enhanced physicochemical properties and the unique morphology. Additionally, the results from TEM, Raman, and TGA analyses also indicated the presence of non-filamentous carbon and filamentous carbons with accumulation of Ni species due to the elevated temperature of the reaction. Overall, the NSLF-15 catalysts hold significant potential for industrial-scale application for syngas formation.

Kinetic exploration of CO2 methanation over nickel loaded on fibrous mesoporous silica nanoparticles (CHE-SM)

A novel series of nickel (Ni) loaded on Fibrous Mesoporous Silica Nanoparticles (CHE-SM) support with varying Ni contents (x=1–30 wt%) were synthesized, denoted as xNi/CHE-SM and then investigated for carbon dioxide (CO2) methanation. The catalysts underwent comprehensive characterization using XRD, N2 adsorption-desorption, FESEM, FTIR-KBr, H2-TPR, and CO2-TPD techniques. The XRD and FESEM analyses confirmed the structural integrity of CHE-SM, irrespective of the Ni loading. However, the size of the nanocrystalline NiO particles appeared to be influenced by the Ni loading. Notably, 20Ni/CHE-SM exhibited the highest CO2 conversion of 92% at 350 °C, demonstrating its potential for low-temperature activation. H2-TPR and CO2-TPD results revealed favorable NiO reduction at lower temperatures, indicating medium-strength basicity that facilitated efficient CO2 and H2 adsorption and activation. Consequently, 20Ni/CHE-SM exhibited superior catalytic performance compared to other catalysts, with lower activation energy (61.5 kJ/mol). Kinetic studies focusing on 20Ni/CHE-SM indicated a molecular adsorption mechanism of CO2 and H2 on a single site after evaluation using four Langmuir-Hinshelwood models. This result was attributed to the high amount of medium strength basicity possessed by the 20Ni/CHE-SM catalyst which provided an abundance of adsorption sites, resulting in greater fractional coverage of reactants and enhancing the CH4 formation rate.

Structural, thermal and optical properties of nickel nanomaterial synthesized by the open-air heat treatment method

In this present research, as a result of heat treatment in the open using a furnace at a temperature of 500 °C, the nickel-coated carbon fibers in this work were successfully created with the nanocrystalline NiO monolayer. The thermal and optical properties (PL) of these materials were investigated using their structural, morphological, compositional, X-ray diffraction (XRD), differential scanning calorimetry (DSC), ultraviolet–visible analysis (UV–Vis), and photoluminescence spectroscopy, as well as scanning electron microscopy (SEM) with the option of chemical analysis (EDS). According to the XRD model, the structure of the produced NiO nanoparticles is the face-centered cubic (fcc) phase. In addition, the DSC shows that the produced nanoparticles form a NiO phase at 360 °C with good thermal stability, and from the optical absorption spectra of the NiO nanoparticles, it is possible to infer that the band gap is 3.5 eV, which is close to the values used as references, also, the significant absorption edges at 287 nm (4.32 ev), 327 nm (3.79 ev), 346 nm (3.58 ev), 397 nm (3.12 ev), and 430 nm (2.88 ev) are seen in the photoluminescence (PL) spectrum, as well, in the violet emission band, the strongest peak has a wavelength of 397 nm and an excitation wavelength of 470 nm (2.64 eV).

Facile synthesis and characterization of ZnO:Al/ZnS/NiO heterojunction thin films with enhanced photocatalytic activities

This study covers a physical investigation of ZnO:Al/ZnS/NiO heterojunction thin films and their photocatalytic activities. The obtained samples were analyzed using XRD, FTIR, SEM/EDS, AFM, and UV–vis spectroscopy. The XRD and FTIR results confirmed that the nanocrystalline ZnO, ZnS, and NiO phases were successfully prepared. SEM morphological analysis of the multilayer film indicated that depositing different nanocrystalline layers above one another could deteriorate the adherence of the upper layer. In addition, AFM shows acceptable surface roughness for application as a photocatalyst. Optical analysis revealed that the ZnO:Al/ZnS/NiO multilayer film exhibited an average transmittance of 65%. The Eg value of the ZnO:Al monolayer of 3.26 eV is decreased to 3.15 eV after Al–ZnO/ZnS coupling, whereas ZnO:Al/ZnS/NiO exhibits an additional absorption value of 3.52 eV due to the NiO layer. The photocatalytic activity of ZnO:Al/ZnS/NiO under visible light exhibited an approximately 96% photodegradation efficiency against methylene blue after only 50 min. However, under sunlight, the degradation rates reached 90, 85, and 65% for methylene blue, crystal violet, and Congo red, respectively, in 90 min. This study shows that a synthesized ZnO:Al/ZnS/NiO heterojunction multilayer photocatalyst can efficiently degrade organic pollutants.

Boosting total oxidation of methane over NiO nanocrystalline decorated ZnO-CoNi solid solution via photothermal synergism

In the context of global warming and atmospheric methane growth, photo-assisted total oxidation of methane is of great importance to diminish greenhouse effect. However, catalytic oxidation of methane at ambient conditions remains a formidable challenge because of its high structure stability. Herein, we report a highly active and stable NiO nanocrystalline decorated on ZnO-CoNi solid solution (NiO/ZnO-CoNi) catalyst which enables 88 % photocatalytic conversion of methane to CO2 and H2O under ambient conditions to maintain a continuous reaction. The unprecedented photocatalytic performance of NiO/ZnO-CoNi originates from the high mobility of surface lattice oxygen of supported NiO nanocrystallines driven by the photogenerated electrons and internal electric field of ZnO-CoNi solid solution. More importantly, the methane conversion of NiO/ZnO-CoNi remains higher than 37 % even when the methane concentration is up to 5000 ppm, showing promise for methane elimination applications in the vicinity of large methane emission sources.

Room temperature RF magnetron sputtered nanocrystalline NiO thin films for highly responsive and selective H2S gas sensing at low ppm concentrations

We report on the H2S gas sensing performance of nanocrystalline NiO thin films sputtered on alumina substrate via RF magnetron sputtering using NiO target at room temperature. Nanocrystalline nature with granular morphology of the films was observed along with the hydrophobic nature (θw ∼ 123.5°), as investigated by GIXRD, FESEM, and wettability measurements. PL spectrum indicates the presence of oxygen or nickel vacancies/defects, which was further confirmed by the XPS measurements. The H2S gas sensing characteristics of NiO thin films have been studied at different operating temperatures (200–425 °C) and gas concentrations (1–200 ppm). It shows the highest sensor response (Rg/Ra) of ∼ 28.8 for 200 ppm H2S gas at 400 °C (with a fast response/recovery time of ∼ 108 s/47 s). Further, NiO thin films confirm the high sensitivity, selectivity, and stability towards H2S gas with detection limit of 135 ppb. The H2S gas sensing mechanism with NiO is also explained.

Influence of annealing temperature on the structural, morphological, and optical properties of nanocrystalline NiO and Cu-doped NiO thin films and its application in acetone gas sensing

Influence of annealing temperature on the structural, morphological, and optical properties of nanocrystalline NiO and Cu-doped NiO thin films and its application in acetone gas sensing

Defect Structure of Nanocrystalline NiO Oxide Stabilized by SiO2

In this paper, structural features of the NiO-SiO2 nanocrystalline catalyst synthesized by the sol-gel method were studied by X-ray diffraction (XRD), high-resolution transmission electron microscopy (TEM), and differential dissolution (DD). The XRD pattern of NiO-SiO2 significantly differs from the “ideal” NiO pattern: the peaks of the NiO-like phase are asymmetric, especially the 111 diffraction peak. The NiO-SiO2 nanocrystalline catalyst was investigated by means of XRD simulations based on two approaches: conventional Rietveld analysis and statistical models of 1D disordered crystals. Through a direct simulation of XRD profiles, structural information is extracted from both the Bragg and diffuse scattering. XRD simulations showed that the asymmetry of all the diffraction peaks is due to the presence of two NiO-like oxides with different lattice constants and different average sizes: ~90 wt% of mixed Ni-Si oxide (Ni:Si = 0.14:0.86) with average crystallite sizes (D ~ 27.5 Å) and ~10 wt% of pure NiO (D ~ 50 Å). The high asymmetry of the 111 diffraction peak is due to the appearance of diffuse scattering caused by the inclusion of tetrahedral SiO2 layers between octahedral NiO layers. Such methods as TEM and DD were applied as independent criteria to prove the structural model, and the results obtained confirm the formation of mixed Ni-Si oxide.

Influence of synthesis methods (combustion and precipitation) on the formation of nanocrystalline CeO2, MgO, and NiO phase materials

Attempts were made to prepare CeO2, MgO, and NiO nanomaterials by combustion and precipitation methods using aniline as a fuel and KOH as a precipitating agent (with the aid of PEG as a surfactant). The formation of CeO2, Mg(OH)2, and NiO as combustion products, and CeO2, Mg(OH)2, and Ni(OH)2 as precipitated products were obtained in a single step. In a single-step process, both combustion and precipitation methods yield CeO2 materials with the significant differences in XRD structural features. The annealing (500 °C/4h) treatment enhances the nanocrystalline nature with the formation of pure MgO, NiO, and CeO2 phases. Variation in refined lattice parameters is noted for the present different materials. The color appearance of the as-prepared and annealed materials obtained by these methods is differentiated. The as-prepared Ni(OH)2 phase materials produced via precipitation with PEG and without PEG as surfactant show a quite major difference in the structural (a, c, and D values) and thermal (TG/DTA) features. The phase pure as-prepared combustion product of CeO2 materials shows a relatively minimum weight loss of 1.4%. A maximum weight loss of 33.9% was noted for the precipitated product of Mg(OH)2 phase materials reduced to 28.2% despite the formation of pure MgO phase materials upon annealing at 500 °C/4h at the end temperature, 1000 °C. The UV–Vis diffuse reflectance measurements exhibit a difference in the absorbance peak intensity and the Eg values calculated from the Tauc relation ranging from 1.65 to 5.42 eV for annealed MgO, NiO, and CeO2 phase materials. Significant changes in the NIR reflectance (<10 – 80%) values are seen in the 750–2500 nm regions for these nanomaterials owing to the difference in the color appearance of powder samples. From the NIR reflectance spectral study, we found that the MgO and CeO2 nanomaterials are suitable for NIR reflecting solar and color pigmentation applications owing to their higher (∼80%) NIR reflectance values in the NIR region.

The preferable Ni quantity to boost the performance of FSA for dry reforming of methane

The spherical mesoporous Ni/fibrous silica-alumina (Ni/FSA) catalysts with varied Ni loadings (5–15 wt%) were effectively synthesized via hydrothermal method followed by impregnation method and catalytically evaluated through employing dry methane reforming. The XRD and FESEM mapping assessment demonstrated that the FSA has structural robustness independent of Ni loading quantities, and the NiO nanocrystalline size relies on the quantity of Ni loading. The mapping of FESEM images demonstrated the dispersion of Ni nanoparticles across the spherical form FSA, with 12.5Ni/ FSA exhibiting the most homogeneous distribution. The BET report indicated that when Ni loading was increased, the surface area of the catalysts increased to 645 m2/g via 12.5 % of Ni. However, in the case of 15Ni/FSA, Ni agglomeration was found. 12.5Ni/FSA gave the highest catalytic efficiency and stability (XCO2 = 82.16 %, XCH4 = 97.16 %, and H2/CO = 0.91). The stability test revealed no trace of deactivation after 60 h of time-on-stream. In concordance with the spent catalyst, XRD, Raman, and TGA investigations showed the graphitic carbon nonattendance for all spent Ni/FSA specimens, and the medium basicity noted by IR-pyrrole analyses, could be attributed to enhanced efficiency of the catalyst. According to the enhanced performance of 12.5Ni/FSA, there was a substantial synergistic impact between the Ni active metal sites and the FSA support, which boosted the reactivity based on both gaseous reactants, CH4 and CO2. The 12.5 wt% Ni was determined to be the optimum Ni value for inhibiting coke deposition on the FSA and hence improving catalytic performance.

Fabrication of nanocrystalline Ga2O3-NiO heterojunctions for large-area low-dose X-ray imaging

The Ga2O3 photoconductor possesses a wide bandgap, a relatively large density and a high absorption coefficient for low-energy X-ray. Therefore, it is expected to realize a highly sensitive low-energy X-ray detector. Realizing p-n heterojunctions using Ga2O3 thin film is essential for large-area low-dose X-ray imaging. Here, a p-n diode consisting of nanocrystalline Ga2O3 thin film and NiO thin film is successfully prepared by electron beam evaporation, exhibiting a large current rectification ratio of 6.0 × 104. The p-n heterojunction shows a large valence band offset of 1.7 eV, a large conduction band offset of 0.84 eV and a built-in potential of 0.2 eV near the interfacial region, benefiting for separation and migration of photogenerated carriers. In addition, the photoconductive gain mechanism of Ga2O3/NiO heterojunction based X-ray detectors with optimized NiO thickness is investigated, achieving a high internal gain (3.3 × 103), a high sensitivity (3.4 × 104 μCGyair−1 cm−2), a low detection limit (42 μGyair s−1) and a short response time (2.2 ms). The optimized detectors with 10 × 10 pixels show a uniform X-ray response, demonstrating their promising use in large-area X-ray imaging applications.

Structural Defect Impact on Changing Optical Response and Raising Unpredicted Ferromagnetic Behaviour in (111) Preferentially Oriented Nanocrystalline NiO Films

NiO thin films deposed on a glass substrate, “NiO/glass”, are successfully prepared using a spray pyrolysis technique (SPT) at 460 °C and characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray, Atomic force microscopy (AFM), spectroscopic ellipsometry (SE), Photoluminescence (PL) and diverse electric and magnetic studies. The structural investigation shows that the synthesized films crystallized in a cubic structure with (111) preferential orientation. The NiO layers exhibit a uniform grain of regular sizes with aggregates randomly distributed across their surface. The optical properties of the NiO thin films evidenced a normal optical dispersion as well as good transparency of the NiO films. An unpredicted ferromagnetic aspect was raised due to the high oxygen presence in the synthetized material. A high thermal dependency of the conductivity, as well as a semiconductor behavior of the grown NiO material, is also demonstrated.

Structural, Dielectric and Vibration Properties of Nio Nanocrystalline Powder Prepared by Ball Milling Method

Structural, Dielectric and Vibration Properties of Nio Nanocrystalline Powder Prepared by Ball Milling Method

Green synthesis and characterisation of nanocrystalline NiO-GDC powders with low activation energy for solid oxide fuel cells

This work reports the preparation of nanocrystalline Ni-Gd0.1Ce0.9O1.95 (NiO-GDC) anode powders using a novel single-step co-precipitation synthesis method (carboxylate route) based on ammonium tartrate as a low-cost green precipitant. The thermogravimetric analysis (TGA) of the synthesised powder showed the complete calcination/crystallisation of the resultant precipitates to take place at 500 °C. The prepared NiO-GDC powder was coated on a GDC electrolyte disc and co-sintered at 1300 °C. A mixture of La0.6Sr0.4Co0.2Fe0.8O3−δ and GDC was used as the cathode material and subsequently coated onto the anode-electrolyte bilayer, resulting in the fabrication of a NiO-GDC|GDC|La0.6Sr0.4Co0.2Fe0.8O3−δ-GDC cell. The crystallite size of both NiO and CeO2 phases were estimated using the X-ray powder diffraction (XRD) profiles and were calculated to be ~14 nm. Applied H2 temperature-programmed reduction (H2-TPR) analysis indicated a synergetic effect among different anode composites' constituents, where an intense interaction between the dispersed NiO nanocrystalline particles and the GDC crystallite phase had weakened the metal-oxygen bonds in the synthesised anode composites, resulting in a strikingly high catalytic activity at temperatures as low as 300 °C. The electrochemical impedance spectroscopy (EIS) and the electrochemical performance of the fabricated cells were measured over a broad range of operating temperatures (500–750 °C) and H2/Ar-ratios of the anode fuel (e.g. 100%–15%). Quantitative analysis from the EIS data and the application of the distribution of relaxation times (DRT) method allowed for the estimation of the activation energies of the anodic high and intermediate frequency processes that were 0.45 eV and 0.76 eV, respectively. This is the first report of a NiO-GDC synthesis, where a considerable improvement in activation energy is observed at the low-temperature region. Such low activation energies were later associated with the adsorption/desorption process of water molecules at the surface of NiO-GDC composite, indicating a high activity towards hydrogen oxidation.

Preparation and characterization of nanocrystalline NiO by the thermal decomposition of oxalate salts for the dehydrogenation of 2-butanol to methyl ethyl ketone

In the present study, highly active nanocrystalline nickel oxide samples were prepared by using a simple, solvent-free, and cost-effective preparation method. Commercial nickel oxalate dihydrate powder was mixed with deionized water to form a soft paste which was sonicated till dryness and then, calcined in static air. The prepared nickel oxide samples were characterized by means of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and N2 adsorption-desorption techniques. The surface basicity of the prepared oxide samples was measured by adsorption of CO2 molecules followed by desorption measurements using the thermogravimetry (TG) technique. The catalytic activity of the prepared nickel oxide samples towards the dehydrogenation of 2-butanol to methyl ethyl ketone (MEK) was studied at a temperature range of 225-325°C. The effects of calcination temperature, reaction temperature, and weight hourly space velocity WHSV on the catalytic activity were studied to determine the best calcination temperature and the optimum operating conditions. The sample calcined at 400°C showed the highest activity and the optimum operating conditions were found to be at the reaction temperature of 300°C and WHSV of 15 L h-1 g-1. The selectivity to MEK was higher than 85% for all the conducted experiments.

2-D NiO nanostructured material for high response acetaldehyde sensing application

The two-dimensional (2-D) nanocrystalline NiO nanoparticles were prepared using a chemical route. The prepared NiO material was well characterized and used for sensor device fabrication. The NiO sensor device exhibited a remarkable response for acetaldehyde in the concentration range of 2–100 ppm. The response of the NiO sensor was investigated for acetaldehyde sensing at different operating temperatures. The high response of the sensor device was noted to be 108% for 100 ppm acetaldehyde concentration at 250 ˚C. The low detection of acetaldehyde was achieved as 3% response for 2 ppm at 250 ˚C. The selectivity of the sensor was tested among gases such as ethanol, methane, carbon monoxide, carbon dioxide, and acetaldehyde. The real-time sensor’s response was studied for different concentrations of acetaldehyde. The effect of acetaldehyde concentrations on the sensor’s response was analysed. The NiO sensor’s stability was confirmed and the sensing mechanism for acetaldehyde gas was briefed.

Boosting NiO Catalytic Activity by x wt % F‐ions and K2O for the Production of Methyl Ethyl Ketone (MEK) via Catalytic Dehydrogenation of 2‐Butanol

AbstractHerein, the synthesis of pure and modified mesoporous nanocrystalline NiO is reported. The catalyst was modified with different wt % F‐ions or K2O and used to produce Methyl ethyl ketone (MEK) as a potential fuel/solvent. XRD analysis of the promoted catalysts confirmed the formation of Ni‐metal covered by the host oxide, compared with pure NiO, especially for the promoted catalysts with x wt % F‐ions. CO2‐TPD results demonstrated the existence of different basic sites over these catalysts with varying strength. The catalytic conversion of sec‐butanol (SB) into MEK over the parent NiO catalyst showed 52 % and 76.8 % conversion of SB at 250 and 275 °C, respectively, with higher selectivity to MEK &gt;96 %. Among the promoted catalysts, NiO‐10 wt % F− and NiO‐1 wt % K2O catalysts showed 99 and 95 % conversion, respectively, with retaining the MEK selectivity of ≥96 %. The catalytic activity, of the most active catalysts, was correlated with the presence of Ni/NiO interfaces, different types of basic sites, especially strong basic sites, and the surface area and porosity measurements.

Spectroscopic ellipsometry and morphological studies of nanocrystalline NiO and NiO/ITO thin films deposited by e-beams technique

The current article reported a new data on the structural, surface morphology and optical properties of multi-thickness nanocrystalline NiO/glass substrate and NiO/ITO/glass substrate semiconductor thin films prepared by electron beam deposition technique. Structural investigation shows that the as-deposited multi-thickness NiO films deposited on a glass substrate crystallize in the form of cubic NaCl type structure. However, ITO thin film has a cubic type structure. Besides, the increase in the crystallite size was observed with increasing the thickness of NiO film, this behavior was confirmed by AFM micrographs. In the spectral range 280 nm–1800 nm, the optical properties of the NiO/glass substrate and NiO/ITO/glass substrate thin films have been investigated using spectroscopic ellipsometry (SE) technique. For NiO/glass substrate sample, the SE results providing direct energy E g d i r ≈ 3.954 eV, indirect energy E g i n d i r ≈ 2.855eV and phonon energy of order 200 meV. In addition, the analysis of the refractive index dispersion gives the atomic number density to be N f i j = 2.213 x 10 22 c m − 3 . On the other hand, for the NiO (410 nm)/ITO (99 nm)/glass substrate thin film sample, a reduction in the direct transition energy to E g d i r ≈ 3.24eV and also in the factor N f i j to 1.6 x 10 22 c m − 3 was observed. Additionally, the values of the oscillator parameters were calculated for NiO/glass substrate and NiO/ITO/glass substrate thin films using the Wemple-DiDomenico single oscillator model (WDD). Finally, it was found that the values of Urbach energy for NiO/glass substrate and NiO (410 nm)/ITO (99 nm)/glass substrate are very small relative to the energy gap values which indicates that the region of localized sates is very narrow compared to the width of the energy gap. • The D/nm of NiO film increase from 16.86 to 22.75nm and for NiO/ITO from 15 to 26nm with increasing thickness from 75 to 410nm. • Good correlation between the increase in D/nm and reduction of dislocation density (δ) is found. • SE provides E g d i r ≈ 3.954 eV, E g i n d i r ≈ 2.855eV and E phon 200meV. For NiO/glass film a reduction in E g d i r to 3.24eV for the NiO(410nm)/ITO (99 nm)/glass. • The refractive index of NiO film is independent of the film thickness and atomic number density is found to be N f i j = 2.213 x 10 22 c m − 3 • The values of E o = 6.828eV, E d = 19.3eV for NiO film and E o = 4.56eV, E d = 15.1eV for (410 nm)/ITO (99nm)/glass substrate film are found.

Enhancing the Efficiency and Stability of PbS Quantum Dot Solar Cells through Engineering an Ultrathin NiO Nanocrystalline Interlayer.

Significant progress in PbS quantum dot solar cells has been achieved through designing device architecture, engineering band alignment, and optimizing the surface chemistry of colloidal quantum dots (CQDs). However, developing a highly stable device while maintaining the desirable efficiency is still a challenging issue for these emerging solar cells. In this study, by introducing an ultrathin NiO nanocrystalline interlayer between Au electrodes and the hole-transport layer of the PbS-EDT, the resulting PbS CQD solar cell efficiency is improved from 9.3 to 10.4% because of the improved hole-extraction efficiency. More excitingly, the device stability is significantly enhanced owing to the passivation effect of the robust NiO nanocrystalline interlayer. The solar cells with the NiO nanocrystalline interlayer retain 95 and 97% of the initial efficiency when heated at 80 °C for 120 min and treated with oxygen plasma irradiation for 60 min, respectively. In contrast, the control devices without the NiO nanocrystalline interlayer retain only 75 and 63% of the initial efficiency under the same testing conditions.