Ultraviolet Ozone Treatment Research Articles

Interfacial Modification of ZnO/ZnMgO Bilayer for Efficient and Stable InP Quantum Dot Light-Emitting Diodes via Ultraviolet Ozone Treatment.

The development of efficient charge transport layers is crucial for realizing high-performance and stable quantum dot light-emitting diodes (QD-LEDs). The use of a ZnO/ZnMgO bilayer as an electron transporting layer (ETL) has garnered considerable attention. This configuration leverages the high electron mobility of ZnO and the favorable surface state of ZnMgO. Furthermore, the versatility of this configuration extends to its wide range of thickness tunability, rendering it suitable for the construction of thick devices for top-emitting structures with microcavities. However, despite the promising attributes of this bilayer configuration, the impact of the ZnO/ZnMgO bilayer ETL interface on QD-LEDs performance remains largely unexplored. Thus, this study investigated the effect of ultraviolet ozone (UVO) treatment on the stabilization of the ZnO/ZnMgO interface. UVO treatment was found to significantly enhance luminance uniformity across the QD-LEDs emission area while improving operational stability by over 4-fold. Comprehensive analyses employing X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy confirmed that UVO treatment significantly reduced the defect states of the hydroxyl groups and removed the insulating native ethanolamine ligands, thereby facilitating improved and uniform electron transport. Moreover, the effectiveness of UVO treatment in enhancing electron transport was supported by impedance analyses. Therefore, this paper presents an effective approach for enhancing the interface of a highly potent ZnO/ZnMgO bilayer ETL, which can ultimately improve the luminance uniformity and stability of QD-LEDs.

Scalable Photo-Responsive Physical Unclonable Functions via Particle Kinetics.

The increasing menace of counterfeiting and information theft underscores the urgent need for security platforms compatible with both micro- and nanoelectronics. Existing methods for anticounterfeiting labeling and cryptographic systems rely on unclonable patterns derived from the unpredictable variability of physical phenomena. However, these approaches impose limitations on the scalability of security components. Here we present a scalable platform for photoresponsive physically unclonable functions based on oxide particle kinetics in polymer solutions. The stochastic agglomeration process occurring during the formation of polymer films with dispersed oxide particles yields random patterns, with pixel sizes scalable from micro to nanoscales. We produce mechanically flexible and self-destructible optical unclonable function patterns utilizing oxide aggregates on a polymer film. Moreover, we establish a strategy for generating electrical unclonable patterns on a conducting polymer film. This involves covering the polymer film with an aggregate pattern mask, which serves as an ultraviolet-blocking layer for randomly exposing the film to ultraviolet ozone treatment. These unclonable patterns constitute robust and compact security systems, exhibiting effective resilience against machine-learning attacks (∼50% prediction error for training data sets of 1000). The developed scalable platforms for physically unclonable functions provide a hardware solution for robust cryptographic applications.

Simple and reversible method to control the surface energy of ITO branched nanowires for tuning wettability of micro/nanoscale droplets

Reversible control of hydrophobic and hydrophilic surfaces has gained attention due to their potential applications in microfluidic devices, membranes for electrochemical cells, and sensors. While external stimuli such as temperature and electric field can regulate surface properties, they cannot be selectively applied to specific regions, which limits the patterning of areas with different surface energies. Here, we present a simple and reversible method for converting hydrophobic and hydrophilic properties through surface treatments involving nonpolar (−CFx) or polar groups (–OH) on indium tin oxide branched nanowires (ITO BRs). The formation of nonpolar groups results in superhydrophobic surface. Subsequent ultraviolet ozone treatment, using a shadow mask, induces the exposed area to transition into a superhydrophilic state, while the unexposed area retains superhydrophobicity. This demonstrates the potential for selective-area surface energy patterning. Furthermore, we investigate the wetting behavior of nanoscale Ag nanoparticles (NPs) on surface-modified ITO BRs. It is observed that size and shape of Ag NPs depend on the surface energy of ITO BRs. Consequently, controlling the surface energy leads to the formation of unique geometric structure of Ag NPs, enhancing plasmonic light absorption and scattering at specific resonant wavelengths.

Effects of UV ozone treatment on the photoresponse of the Pt nanoparticles decorated WS2

Chemical vapor deposition (CVD)-grown and Pt nanoparticles (NPs) decorated multilayer WS2 is treated by ultraviolet (UV) ozone for the modification of the surface roughness to realize the enhanced hot carriers injection via the internal photoemission (IPE). The morphology, structure and photophysical properties as well as the dependence of the photoresponse on the UV ozone treatment are investigated. The UV ozone treatment demonstrates obvious effect on the WS2 surface roughness (Sa), which reaches the maximum around 14 nm after 2 min exposure and subsequently decrease with the extension of treatment duration. UV ozone treatment also leads to obviously diminished photoluminescence (PL) and shortened excitons lifetime for bare WS2 while its influence on the electronic structure is negligible. The diminished PL, shortened PL decaying lifetime and increased Sa are all originated from the formation of WOx due to the consumption of top WS2 layer by the severe oxidation, and such effects will be greatly alleviated when the fresh and undisturbed underlying WS2 layer appears with the treatment duration extended to 4 min. The 2 min UV ozone treated WS2/Pt exhibits optimal wide spectrum photoresponse (400–900 nm) with the near infrared (NIR) responsivity around 18 A/W at 750 nm, about 60 % higher compared to that of untreated one while the 4 min overtreated WS2/Pt demonstrates much deteriorated photoresponse. Such behavior can be ascribed to the enhanced hot electrons injection from Pt to WS2 due to the formation of rough Schottky contact as well as the separation of photo-excited electron-hole pairs by Schottky junction. Our study proves that the Sa is a key factor not only for the exciton dynamics but also for the hot electron injection from Pt to WS2.

Enhancing fiber-reinforced asphalt binders via graphene oxide grafting: A novel interfacial modulation strategy

This study reports a novel interfacial enhancement strategy for fiber-reinforced asphalt binders. The graphene oxide (GO) nanosheets were used and grafted onto polyester (PET) and polyacrylonitrile (PAN) fibers in order to enhance the performance of modified asphalt binders. Prior to this, ultraviolet ozone (UVO) treatment was primarily adopted for activating the inert surface of fibers. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Scanning electron microscope (SEM) confirmed that GO-modified fibers were successfully prepared via surface modification. For the rheological properties determined by dynamic shear rheometer (DSR), the asphalt binders with GO-modified fibers exhibit improved high-temperature rutting resistance, better creep and recovery characteristics and increased anti-fatigue properties. Remarkably, it demonstrates that the recovery (R) value of GO-PAN modified asphalt binder is increased by 21.9 %, and the non-recoverable compliance (Jnr) value of GO-PET modified asphalt binder has been reduced by 31.9 % compared to that reinforced with the unmodified fiber in multiple stress creep recovery (MSCR) tests. These enhancements are mainly attributed to the increased roughness and modulus of the GO-grafted fibers, which promote effective stress transfer at the fiber-asphalt interfaces. Results from the atomic force microscope (AFM) indicate that the Young’s modulus of GO-PET and GO-PAN is 94.2 % and 260.0 % higher than that of PET and PAN, respectively. This research not only provides a simple and cost-effective method for improving the rheological performance, but also elucidates the enhancement mechanism of interfacial behavior in fiber-reinforced asphalt binders.

Enhanced Performance of Polymer Solar Cells by Ultraviolet-Ozone Treatment of MoOX Films with non-Thermal Annealing Treatment of MoOX Films

Molybdenum oxide (MoOX) is a commonly used hole extraction material (HEL) in polymer solar cells (PSCs). Here, we perform ultraviolet ozone treatment (UVO, non-thermal annealing treatment) on MoOX film (by spin-coated (NH4)6Mo7O24-4H2O solution on the ITO top) prepared by solution processing to develop hole extraction materials for efficient PSC. After UVO treatment of MoOX films (US-MoOX), the (NH4)6Mo7O24-4H2O molecules decompose to form a denser and higher energy levels MoOX film. Compared with E-MoOX films (vacuum evaporated MoO3 powder), US-MoOX films have similar square resistance and electrical conductivity to E-MoOX films, and the photovoltaic performance of US-MoOX-based PSCs is comparable to that of E-MoOX-based PSCs and higher than that of PEDOT:PSS-based PSCs. Therefore, US-MoOX-based PSCs show the advantages of combining high photovoltaic performance with solution processing. In addition, US-MoOX-based PSCs have the advantage of not requiring thermal annealing treatment. The results indicate that US-MoOX films are promising HEL materials for the practical production of PSCs.

Photochemical optimization of fluorescent dye-doped PDMS for enhanced luminescent solar concentrator performance

Luminescent solar concentrators (LSCs) that incorporate organic dyes face challenges such as self-absorption loss and aggregation-caused quenching (ACQ) as doping concentration increases, limiting the dye loading capacity. Particularly for dyes with a small Stokes shift, losses due to self-absorption or quenching are prominent even at low concentrations, hindering the attainment of high power conversion efficiency (PCE) in LSCs. Additionally, exposure of the dye-impregnated polymer matrix to oxygen, moisture, UV light, and other factors leads to a decrease in luminescence efficiency and stability due to the photooxidation reaction of the phosphor. This study presents a facile approach for enhancement of the efficiency and environmental stability of coumarin 6 (C6) dye-doped polydimethylsiloxane (PDMS) LSC through ultraviolet ozone (UVO) treatment. Photocleavage of the C6 dimer into a C6 monomer through UVO treatment leads to a significant enhancement in luminescence. Additionally, thin SiOx layers formed on both sides of the LSC not only assist in capturing luminescent light more efficiently but also block the penetration of oxygen and moisture into the LSC, resulting improved device stability. UVO-treated LSC shows approximately 32 % improvement in PCE compared to bare LSCs and exhibits significantly better stability during the 30-day long-term performance test.

A Dual-Channel MoS2-Based Selective Gas Sensor for Volatile Organic Compounds.

Significant progress has been made in two-dimensional material-based sensing devices over the past decade. Organic vapor sensors, particularly those using graphene and transition metal dichalcogenides as key components, have demonstrated excellent sensitivity. These sensors are highly active because all the atoms in the ultra-thin layers are exposed to volatile compounds. However, their selectivity needs improvement. We propose a novel gas-sensing device that addresses this challenge. It consists of two side-by-side sensors fabricated from the same active material, few-layer molybdenum disulfide (MoS₂), for detecting volatile organic compounds like alcohol, acetone, and toluene. To create a dual-channel sensor, we introduce a simple step into the conventional 2D material sensor fabrication process. This step involves treating one-half of the few-layer MoS₂ using ultraviolet-ozone (UV-O3) treatment. The responses of pristine few-layer MoS₂ sensors to 3000 ppm of ethanol, acetone, and toluene gases are 18%, 3.5%, and 49%, respectively. The UV-O3-treated few-layer MoS₂-based sensors show responses of 13.4%, 3.1%, and 6.7%, respectively. This dual-channel sensing device demonstrates a 7-fold improvement in selectivity for toluene gas against ethanol and acetone. Our work sheds light on understanding surface processes and interaction mechanisms at the interface between transition metal dichalcogenides and volatile organic compounds, leading to enhanced sensitivity and selectivity.

The Potential of Tellurene‐Like Nanosheets as a Solution‐Processed Room‐Temperature Thermoelectric Material

Low‐dimensional thermoelectric materials systems are proven to possess improved thermoelectric performance, either by enhancing the power factor S2σ through quantum confinement, or decreasing thermal conductivity with numerous interfaces. The 2D tellurium, also called tellurene, is a newly discovered 2D material which showed great potential for thermoelectric applications. In this article, high‐quality tellurene‐like nanosheets are synthesized by the hydrothermal method and assembled into nanostructured bulk materials by low‐temperature hot press, and their thermoelectric performance is investigated. Ultraviolet–ozone treatment is used to remove organic surface ligands. Doping is realized with surface doping with chalcogenidometalates. It is found that the Seebeck coefficient and the thermal conductivity of the nanosheet‐assembled bulk samples increased by ≈20% and decreased by 43% compared to bulk tellurium, respectively. Meanwhile, the carrier mobility is approaching, yet still lower than bulk tellurium. Overall, the best bulk sample possesses a zT of 0.1 at room temperature which is comparable to bulk Te. By further improving the mobility, this solution processable material can provide useful thermoelectric performance for room‐temperature applications.

High-Performance Organic Field-Effect Transistors of Liquid Crystalline Organic Semiconductor by Laser Mapping Annealing.

Organic semiconductors (OSCs), especially small molecule semiconductors, have received increasing attention due to their good designability and variability. Phase transitions and interfacial properties have a decisive influence on device performance. Here, 2-Dodecyl-7-phenyl[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-12) devices are treated with low-power laser annealing, which is able to avoid the influence of the dewetting effect on the hole mobility of organic semiconductor materials. Ultraviolet ozone treatment and self-assembled monolayer treatment can improve the performance and stability of the device. Moreover, after low-temperature thermal annealing, the hole mobility of the device can even reach as high as 4.80 cm2 V-1 s-1, and we tested the optical response of the device to the ultraviolet wavelength and found that its maximum optical responsivity was 8.2 AW-1.

Fabrication of a Fully Printed Ammonia Gas Sensor Based on ZnO/rGO Using Ultraviolet-Ozone Treatment.

In this study, a room-temperature ammonia gas sensor using a ZnO and reduced graphene oxide (rGO) composite is developed. The sensor fabrication involved the innovative application of reverse offset and electrostatic spray deposition (ESD) techniques to create a ZnO/rGO sensing platform. The structural and chemical characteristics of the resulting material were comprehensively analyzed using XRD, FT-IR, FESEM, EDS, and XPS, and rGO reduction was achieved via UV-ozone treatment. Electrical properties were assessed through I-V curves, demonstrating enhanced conductivity due to UV-ozone treatment and improved charge mobility from the formation of a ZnO-rGO heterojunction. Exposure to ammonia gas resulted in increased sensor responsiveness, with longer UV-ozone treatment durations yielding superior sensitivity. Furthermore, response and recovery times were measured, with the 10 min UV-ozone-treated sensor displaying optimal responsiveness. Performance evaluation revealed linear responsiveness to ammonia concentration with a high R2 value. The sensor also exhibited exceptional selectivity for ammonia compared to acetone and CO gases, making it a promising candidate for ammonia gas detection. This study shows the outstanding performance and potential applications of the ZnO/rGO-based ammonia gas sensor, promising significant contributions to the field of gas detection.

Disinfection of Bacteria in Aerosols by Applying High Voltage to Stranded Wire Electrodes.

The inactivation of airborne pathogenic microorganisms is crucial to attenuate the dissemination of infectious diseases induced by airborne pathogens. Conventional air disinfection methodologies, such as ultraviolet (UV) irradiation and ozone treatment, have demonstrated limited efficacy. Consequently, we investigated the potential of employing pulsed voltages to effectively eradicate bacteria within aerosols. Our inquiry revealed that the bacterial disinfection rate increased proportionally with elevated applied voltage and frequency. For instance, when a pulsed voltage of 20 kV and a frequency of 500 Hz were applied, a substantial disinfection rate exceeding 6.0 logarithmic units was attained. Furthermore, with the utilization of the stranded wire anodes, the disinfection intensity could be augmented by up to 2.0 logarithmic units compared with the solid wire configuration. Through the utilization of a stranded wire electrode model, we scrutinized the electric field encompassing the electrode, revealing a non-uniform electric field with the stranded wire electrode. This observation indicated an amplified bacterial disinfection effect, aligning with our experimental outcomes. These findings significantly enhance our comprehension of efficacious approaches to electrically disinfecting airborne bacteria.

In Situ Monitoring of Non-Thermal Plasma Cleaning of Surfactant Encapsulated Nanoparticles

Surfactants are widely used in the synthesis of nanoparticles, as they have a remarkable ability to direct their growth to obtain well-defined shapes and sizes. However, their post-synthesis removal is a challenge, and the methods used often result in morphological changes that defeat the purpose of the initial controlled growth. Moreover, after the removal of surfactants, the highly active surfaces of nanomaterials may undergo structural reconstruction by exposure to a different environment. Thus, ex situ characterization after air exposure may not reflect the effect of the cleaning methods. Here, combining X-ray photoelectron spectroscopy, in situ infrared reflection absorption spectroscopy, and environmental transmission electron microscopy measurements with CO probe experiments, we investigated different surfactant-removal methods to produce clean metallic Pt nanoparticles from surfactant-encapsulated ones. It was demonstrated that both ultraviolet-ozone (UV-ozone) treatment and room temperature O2 plasma treatment led to the formation of Pt oxides on the surface after the removal of the surfactant. On the other hand, when H2 was used for plasma treatment, both the Pt0 oxidation state and nanoparticle size distribution were preserved. In addition, H2 plasma treatment can reduce Pt oxides after O2-based treatments, resulting in metallic nanoparticles with clean surfaces. These findings provide a better understanding of the various options for surfactant removal from metal nanoparticles and point toward non-thermal plasmas as the best route if the integrity of the nanoparticle needs to be preserved.

Controlled Preparation of Highly Stretchable, Crack-Free Wrinkled Surfaces with Tunable Wetting and Optical Properties.

Constructing wrinkles by utilizing strain-driven surface instability in film-substrate systems is a general method to prepare micronano structures, which have a wide range of applications in smart surfaces and devices such as flexible electronics, reversible wetting, friction, and optics. However, cracks generated during the preparation and use process significantly affect the uniformity of wrinkled surfaces and degrade the functional properties of the film devices. The realization of crack-free wrinkles with high stretchability in hard film systems is still a great challenge. Here, we report on a facile technique for controllable preparation of large-area, highly stretchable, crack-free wrinkled surfaces by ultraviolet ozone (UVO) treatment of Ecoflex. The thickness dependence of the wrinkles and the in situ wrinkling process during mechanical loading are investigated. The wrinkles including striped, labyrinth-like, herringbone, and transitional structures are controllable by changing strain mode (uniaxial or biaxial), loading history (simultaneous or sequential), strain anisotropy, and gradient loading. The wrinkled surfaces obtained using UVO-treated Ecoflex have tunable wetting and optical properties and can maintain excellent mechanical stability under large strains. This study provides a facile method for the preparation of large-area, crack-free wrinkles, which is simple, fast, low-cost, and robust. The resulting wrinkled surfaces remain stable under high stretching, which is beneficial for many practical applications, especially in the cases of large strains.

Surface Adsorption and Air Damping Behavior of β‐Ga2O3 Nanomechanical Resonators

AbstractBeta gallium oxide (β‐Ga2O3) has emerged as a highly promising semiconductor material with an ultrawide bandgap ranging from 4.5 to 4.9 eV for future applications in power electronics, optoelectronics, as well as gas and ultraviolet (UV) radiation sensors. Here, surface adsorption and air damping behavior of doubly clamped β‐Ga2O3 nanomechanical resonators are probed and systemically studied by measuring the resonance characteristics under different gas and pressure conditions. High responsivities of resonance to pressure are obtained by heating the devices up to 300 °C to induce an accelerated adsorption–desorption process. The initial surface conditions of the β‐Ga2O3 thin film play important roles in affecting the resonant behavior. UV ozone treatment proves effective in altering the initial surface conditions of β‐Ga2O3 nanosheets by eliminating physisorbed contaminants and filling oxygen vacancy defects residing on the surface, resulting in a consequential and discernible modification of the resonance behavior of β‐Ga2O3 nanomechanical resonators. The surface adsorption and desorption processes in β‐Ga2O3 demonstrate clear reversibility by exposing the UV treated β‐Ga2O3 to air. This study attains first‐hand information on how the surface conditions of β‐Ga2O3 affect its mechanical properties, and helps guide future development of transducers via β‐Ga2O3 nanoelectromechanical systems (NEMS) for pressure sensing applications, especially in harsh environments.

Nanoarchitectonics for Improving Catalytic Performance of α-Alumina-supported Gold Nanoflower by Water Extraction and Ultraviolet-Ozone Treatment.

Shape-controlled nanocrystals, such as nanoflowers, are expected to serve as innovative nanocatalysts with high catalytic activity. It is well-established that these nanocrystals can be readily synthesized with specific shapes using colloidal methods in solutions containing capping agents. However, these capping agents tend to reduce the catalytic activity of nanocatalysts. Therefore, it is imperative to remove these agents without altering the morphology to enhance catalytic efficiency. In this study, we developed a method for eliminating melamine, a common capping agent, from supported Au nanoflowers using water extraction and ultraviolet-ozone treatment. This process significantly enhances the catalytic performance, particularly for alcohol oxidation reactions such as the conversion of 1-phenylethyl alcohol to acetophenone.

The effect of UVO treatment on TiO2-MAPbI3 heterostructure photodetector prepared in air atmosphere

TiO2-MAPbI3 heterostructure photodetectors were prepared in air atmosphere. The interface between electron transport layer and perovskite layer plays an important role in the performance of heterostructure photodetector. Here, ultraviolet ozone (UVO) treatment was used to improve the surface state of TiO2 film and the interfacial carrier transport performance of perovskite heterostructure photodetector. UVO treatment made TiO2 layer obtain the more oxygen vacancies and excess electrons, which were conducive to the electrical conductivity of electron transport layer. And MAPbI3 film deposited on UVO-treated TiO2 layer showed better uniformity and enhanced light absorption intensity due to the improved wettability of UVO-treated TiO2 film. Further research on photoelectric performance indicated that the increased light current and decreased dark current could be obtained for perovskite photodetector based on UVO-treated TiO2. In addition, the best exposure time was found to be 40 min. Compared with untreated sample, the detectivity of UVO-treated TiO2-MAPbI3 heterostructure photodetector increased by 80 %. Under 500 nm illumination with a light intensity of 1.6 mW cm−2 at −0.8 V bias, the responsivity, detectivity and external quantum efficiency of UVO-treated TiO2-MAPbI3 heterostructure photodetector reached 0.405 A W−1, 2.07 × 1011 Jones and 100.5 %, respectively.

Ultraviolet-Ozone Treatment: An Effective Method for Fine-Tuning Optical and Electrical Properties of Suspended and Substrate-Supported MoS2

Ultraviolet-ozone (UV-O3) treatment is a simple but effective technique for surface cleaning, surface sterilization, doping, and oxidation, and is applicable to a wide range of materials. In this study, we investigated how UV-O3 treatment affects the optical and electrical properties of molybdenum disulfide (MoS2), with and without the presence of a dielectric substrate. We performed detailed photoluminescence (PL) measurements on 1–7 layers of MoS2 with up to 8 min of UV-O3 exposure. Density functional theory (DFT) calculations were carried out to provide insight into oxygen-MoS2 interaction mechanisms. Our results showed that the influence of UV-O3 treatment on PL depends on whether the substrate is present, as well as the number of layers. Additionally, 4 min of UV-O3 treatment was found to be optimal to produce p-type MoS2, while maintaining above 80% of the PL intensity and the emission wavelength, compared to pristine flakes (intrinsically n-type). UV-O3 treatment for more than 6 min not only caused a reduction in the electron density but also deteriorated the hole-dominated transport. It is revealed that the substrate plays a critical role in the manipulation of the electrical and optical properties of MoS2, which should be considered in future device fabrication and applications.

Morphology Engineering of the Asymmetric PS-b-P4VP Block Copolymer: From Porous to Nanodot Oxide Structures.

In the present work, we demonstrate the formation of oxide porous and nanodot structures from the same block copolymer (BCP) by the phase inversion of a BCP template. We investigated the effect of solvent annealing time on the ordering of asymmetric, cylinder forming, polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) BCP. Phase separation of PS-b-P4VP was achieved by solvent vapor annealing (SVA) in a solvent atmosphere that is (partially) selective to P4VP to initially generate hexagonally arranged, cylindrical arrays of the expected structure. The morphology of the BCP changed from P4VP hexagonally packed cylinders to an 'inverse' structure with PS cylinders embedded in a P4VP matrix. This suggests that selective swelling occurs over time such that the swollen P4VP phase becomes the majority volume component. Metal ions (Ga3+, In3+) were infiltrated into the BCP templates by a solution-mediated infiltration approach, followed by an ultraviolet-ozone treatment to remove the polymer and oxidize the metallic ions to their oxides. The findings show that a single BCP can be used to create both metal oxide arrays and porous structures of metal oxides by simply varying the duration of the solvent annealing process. The resulting structures were analyzed through several methods including scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy, and energy-dispersive X-ray spectroscopy. XPS analyses confirmed the complete elimination of the BCP template and the presence of metal oxides. This study provides important insights into the development of functional BCP materials with inverse structures.

Solvent engineering of SnO2 electron transport layer for high-performance perovskite solar cells

Perovskite solar cells (PSCs) show great potential as industrial photovoltaic devices due to their low fabrication cost and high power conversion efficiency. Owing to high electron conductivity and good energy level matching with perovskites, SnO2 is widely used as electron transport layers (ETLs) for PSCs. However, the agglomeration of SnO2 nanoparticles makes them have poor contact with the glass substrate and it is easy to produce defects on the film surface. Herein, acetonitrile (ACN) is used to optimize the conventional solvent of commercial SnO2 colloid to solve these problems. The addition of ACN in solvent resulted in better-performing SnO2 ETLs, thus eliminating the need for long-time ultraviolet ozone (UV-ozone) treatment of the glass substrate, which undoubtedly greatly simplified the fabrication process. The subsequent vacuum treatment of SnO2 films before annealing further improves morphology of the ETLs film and performance of the overall device. Finally, the best devices after the above solvent engineering treatment achieved an efficiency of 22.28%, increased by 16% with respect to the control device fabricated by conventional method. In addition, the long-term stability of devices was also apparently improved. This solvent engineering strategy provides a simple route to prepare high-quality SnO2 ETL for high-performance PSCs.