Thermal Evaporation Approach Research Articles

Single-source thermal deposition of (BA)2(MA)3Pb4I13 perovskite for a novel SnO2NRs/comp-TiO2@ irradiated-ITO based 2D/3D perovskite solar cell: Comparative study of irradiated ITO layer and its effect on device performance

Perovskite solar cells have achieved very good efficiency but their stability is still a big issue. To achieve an efficient a stable perovskite solar cell; a new simple single source thermal evaporation approach has been used to deposit 2D/3D (BA)2(MA)3Pb4I13 perovskite active layer, for realization of novel architecture of stable perovskite solar cell. Bi ions irradiated ITO electrode, coated with compact TiO2 and SnO2 nano-rods (NRs) layers, has been used as ETL. A unique approach is adopted to deliberately place SnO2 NRs horizontally on the surface comp-TiO2 coated irradiated ITO. Four, SnO2NRs/comp-TiO2@ irradiated-ITO based 2D/3D perovskite devices, have been fabricated with 1.2 GeV Bi ions irradiated ITO, at four different fluences (1.3 × 1011, 6.5 × 1011, 1.3 × 1012 and 2.6 × 1012 ions/cm2). Nano-hillocks formed by irradiation proved to contribute for the better performance to a certain point. It was found that the choice of using horizontally place SnO2-NRs in ETL contributed for better performance and stability of proposed device. Among four fabricated devices highest efficiency of 13.6 % is obtained for ITO irradiated with 1.3 × 1012 ions/cm2 fluence which is very encouraging for 2D/3D hybrid perovskite based solar cells in addition to improved performance all the devices showed good stability.

Thermal evaporation-driven fabrication of Ru/RuO2 nanoparticles onto nickel foam for efficient overall water splitting.

Developing high-performance bifunctional electrocatalysts towards the hydrogen evolution reaction/oxygen evolution reaction (HER/OER) holds great significance for efficient water splitting. This work presents a two-stage metal-organic thermal evaporation strategy for the fabrication of Ru-based catalysts (Ru/NF) through growing ruthenium (Ru)/ruthenium dioxide (RuO2) nanoparticles (NPs) on nickel foam (NF). The optimal Ru/NF shows remarkable performance in both the HER (26.1 mV) and the OER (235.4 mV) at 10 mA cm-2 in an alkaline medium. The superior OER performance can be attributed to the synergistic interaction between Ru and RuO2, facilitating fast alkaline water splitting. Density functional theory studies reveal that the resulting Ru/RuO2 with the (110) crystal surface reinforces the adsorption of oxygen on RuO2, while metallic Ru improves water dissociation in alkaline electrolytes. Besides, Ru/NF requires only 1.50 V at 10 mA cm-2 for overall water splitting, surpassing 20 wt% Pt/C/NF||RuO2/NF. This work demonstrates the promising potential of a thermal evaporation approach for designing stable Ru-based nanomaterials loaded onto conductive substrates for high performance overall water splitting.

A Novel combined thermal evaporation and solvothermal approach to produce highly crystalline and compact CIG(S1-xSex)2 thin films

This research introduces a novel approach that combines thermal evaporation with cost-effective solvothermal methods to produce highly crystalline CIGSe thin films. By avoiding the use of expensive and pure target materials and reducing the selenization step, this method offers an alternative to co-evaporation or sputtering techniques. The study investigates the growth mechanism and sulfurization of the films, resulting in improved crystallinity, absence of secondary impurities, and compact morphology. The sulfurization process is achieved at a low temperature using a safe and convenient method, enhancing the film properties for high-performance solar cells. In this study, the CIGSe powder was synthesized using the solvothermal technique and thermally evaporated onto Mo-coated glass substrates. The resulting films exhibited improved crystallinity and a single-phase structure upon RTP annealing at 600 °C. Characterization techniques confirmed the presence of chalcopyrite crystal structure and the coexistence of CISe, CIGSe, and CGSe phases within the films. The sulfurization process, conducted at a relatively low temperature of 500 °C using an RTP furnace, led to compact morphology, increased grain size, and the absence of secondary phases. These findings demonstrate the feasibility of the proposed approach for fabricating efficient and environmentally friendly CIGSe-based solar cells.

Amplified Spontaneous Emission from Thermally Evaporated High-Quality Thin Films of CsPb(Br1-xYx)3 (Y = I, Cl) Perovskites.

As a wavelength-tunable lasing material, perovskites are now generating a lot of scientific attention. Conventional solution-processed CsPbX3 perovskite films sometimes suffer unavoidable pinhole defects and poor surface morphology, severely limiting their performance on amplified spontaneous emission (ASE) and lasing application. Herein, a thermal evaporation approach is explored in our work to achieve a uniform and high-coverage CsPb(Br1-xYx)3 (Y = I, Cl) perovskites polycrystalline thin film. The ASE of these films was studied using a picosecond laser system. The ASE profile increases rapidly over the narrow peak in relation to the laser pump intensity, confirming the development of stimulated emission. ASE began when the energy density threshold was reached and ranged between 25 and 170 μJ/cm2 per pulse for perovskite materials when replacing I with Br and then Cl. This work emphasizes the notable optical properties of high-quality perovskite thin films, leading to possible accessible uses in optoelectronic applications.

Surface fluoride management for enhanced stability and efficiency of halide perovskite solar cells via a thermal evaporation method

Phenethylammonium fluoride is conformally coated on a perovskite film via a simple thermal evaporation approach at low temperatures and normal pressure, passivating the defects and reinforcing the structural stability.

Experimental and theoretical studies of (CdS) 1-x (ZnS)x thin-films for second generation CdS/CdTe solar cells

The current work focused on studying the optical and structural properties of (CdS)1-x (ZnS)x thin films fabricated by thermal vacuum evaporation approach. The evaporation was implemented at room temperature from bulk samples synthesis by sintering approach. The energy gap, index of refraction, extinction coefficient and absorption coefficient were estimated from the experiment and employed in our theoretical model to estimate quantitatively the solar cell efficiency and short-circuit current density of CdS:ZnS/CdTe structure. The calculations of cell efficiency as well as short-circuit current density were computed on the bases of the optical losses caused by reflection at interfaces and absorption process occurred in the frontal charge-collecting and window layers and the recombination losses at front and back surface of CdTe. The XRD analysis showed that the intensity and position of predominant peak of CdS gradually changes with increasing the ZnS content indicating a success of forming CdS:ZnS alloy. The films exhibited direct band-to-band transitions and the optical energy gap increased from 2.40 eV to 3.10 eV with increasing of ZnS content up to x = 0.50. The short-circuit current density increased from 16.50 mA/cm2 to 21 mA/cm2 and the cell efficiency increased from 13.10% to 17.10% due to the increase of the ZnS content from x = 0 to x = 0.50.

Vacuum Dual-Source Thermal-Deposited Lead-Free Cs3Cu2I5 Films with High Photoluminescence Quantum Yield for Deep-Blue Light-Emitting Diodes.

Deep-blue emitters are greatly desirable for preparing white light-emitting diodes and enhancing the color gamut of full-color display. The deep-blue lead halide perovskite light-emitting diodes (PeLEDs) exhibit far inferior performance compared to green and red counterparts and suffer from lead toxicity, hampering their applications. Nontoxic, stable, and wide band gap zero-dimensional (0D) Cs3Cu2I5 with relatively high exciton binding energy has great potential as deep-blue emitters. However, the development of PeLEDs remains a huge challenge due to the difficulties in preparing a high-quality Cs3Cu2I5 film and device design, arising from an inherent wide band gap together with deep ionization potential. Here, a continuous and pin-hole-free Cs3Cu2I5 thin film with deep-blue emission centered at 440 nm was prepared by the dual-source thermal evaporation approach, and a high photoluminescence quantum yield of 58% was achieved, corresponding to significant enhancement of 61% compared with that of the Cs3Cu2I5 thin film synthesized by solution processes. Furthermore, saturated deep-blue PeLEDs at the Commission Internationale de L'Eclairage (CIE) coordinates (0.15, 0.08) were obtained by employing an electron-transfer layer composed of a 1,4,5,8,9,11-hexa-azatriphenylene hexacarboni-trile (HAT-CN) and N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB) organic heterojunction to realize the effective hole blocking, rendering an external quantum efficiency of approximately 0.1%. These results will be extensively beneficial to wide band gap material and device preparation.

A Highly Sensitive Ammonia (NH3) Sensor Based on a Tungsten Trioxide (WO3) Thin Film Decorated With Evaporated Platinum (Pt) Nanoparticles

An interesting ammonia (NH3) sensor based on a tungsten trioxide (WO3) thin film decorated with platinum (Pt) nanoparticles (NPs) is fabricated and demonstrated herein. Pt NPs are prepared by a rapid thermal evaporation (RTE) approach. The small size of these Pt NPs causes an increased surface area/volume ( ${S}_{A}/{V}$ ) ratio and enhanced sensing performance. The experimental results indicate good properties, including a higher sensing response of 72.61 under 1000 ppm NH3/air gas, a lower optimum operating temperature of 225 °C, and a lower detecting limit (≤ 1 ppm NH3/air). The studied device also has the advantages of a simple structure, easy fabrication, relatively low cost, a wide concentration detection range, and stable sensing performance. In addition, a first-order differential (FOD) and shape-preserving piecewise cubic interpolation (SPPCI) algorithms are employed to effectively reduce the redundant results and recover the reduced data for wireless transmission application. Thus, the studied Pt NP/WO3 thin film-based device shows a promise for high-performance ammonia sensing applications.

Fabrication of efficient CsPbBr3 perovskite solar cells by single-source thermal evaporation

It is promising to improve the stability of organic–inorganic hybrid halide perovskite solar cells by using all-inorganic perovskite materials. Herein, a facile one-crucible single-source vacuum thermal evaporation (VTE) approach is developed, which is used to evaporate two different melting points materials CsBr (630 °C) and PbBr2 (370.6 °C) to deposit high-quality inorganic CsPbBr3 perovskite films. Molar ratio of PbBr2 to CsBr in their mixture in the crucible is a key factor influencing the stoichiometry, structure, photoelectrical and photovoltaic properties of the CsPbBr3 films. The other important factor is the thickness of the CsPbBr3 films. High-quality CsPbBr3 films with good uniformity and compact and large grains are prepared. Planar CsPbBr3 perovskite solar cells are fabricated giving a high power conversion efficiency of 8.65%. The fabricated CsPbBr3 solar cells exhibit a good stability in air without encapsulation. This study opens up the possibility to deposit multi-element compound thin films by facile single-source VTE of different melting points materials.

Wafer-scale 3D cloud-like aluminum hierarchical nanostructure for NIR SERS

Plasmonic nanomaterials with a high density of accessible hot spots over a large area are highly desirable for ultrasensitive near-infrared surface-enhanced Raman scattering (NIR SERS) sensing, especially those based on low-cost and earth-abundant noncoinage metals. Here, we report a facile thermal evaporation approach to fabricate 3D hierarchical aluminum cloud-like nanostructures decorated with nanoparticles on a wafer-sized substrate, which can provide high enhancement of Raman signals using 785 nm excitation. This enhancement is attributed to its absorption peak close to the excitation wavelength and high density of hot spots constructed by adjacent large cloud-like nanostructures and/or small nanoparticles. Systematic measurements and statistical analysis show that the obtained NIR SERS substrates exhibit high enhancement factor (1.48×105), long-term stability, and excellent reproducibility with less than 7% standard deviation over a 4-inch wafer surface. The combination of significant enhancement, long-term stability, good reproducibility, and scalable production process suggest that this type of 3D hierarchical aluminum nanostructures hold promise as a robust low-cost plasmonic material for applications in the near infrared SERS operation.

Hydrogen Sensing Characteristics of a Metal–Oxide–Semiconductor Diode With Bimetallic Catalysts and a GaO x Dielectric

A new metal–oxide–semiconductor (MOS) diode with bimetallic catalysts and a GaOx dielectric is employed herein to fabricate a hydrogen sensor. Bimetallic catalysts, including Pt nanoparticles (NPs) and a Pd thin film, are formed by the proper vacuum thermal evaporation (VTE) approach, and a GaOx dielectric is produced by H2O2 treatment on the GaN surface. The presence of this bimetallic structure can effectively increase the surface area-to-volume ratio and provide a “spill-over” effect. This can substantially enhance the dissociation and adsorption of hydrogen molecules and atoms. The use of a GaOx dielectric effectively suppresses the surface leakage current and increases the adsorption sites for hydrogen atoms. Experimentally, excellent hydrogen sensing properties, including a very high sensing response of $1.1 \times 10^{7}$ under 1% H2/air gas at 300 K, an extremely low detection level (≤100 ppb H2/air), a widespread hydrogen concentration sensing range, and a relatively fast sensing speed, were obtained. From a thermodynamic analysis, it is clear that the hydrogen adsorption of the studied device is an exothermic reaction. Therefore, based on the above-mentioned advantages, the studied Pt NP/Pd thin film/GaOx/GaN-based MOS diode shows promise for high-performance hydrogen sensing applications.

Organic Memristor Utilizing Copper Phthalocyanine Nanowires with Infrared Response and Cation Regulating Properties

AbstractCurrent organic memristive devices have been suffering from unstable performance, ambiguous mechanism, and poor NIR response, thus restricting their commercial translation. Here, a near‐infrared‐sensitive (NIR) organic memristive device with high stability based on solution‐processed copper phthalocyanine nanowires (N‐CuMe2Pc NWs) is first reported. Compared with uneven thermal evaporated N‐CuMe2Pc film, the N‐CuMe2Pc NWs film possesses a uniform 3D mesh structure, which attribute to the localized cationic migration, robust formation/rupture of conductive filament and subsequent improvement of reproducibility, thermal stability, and retention characteristics. Furthermore, operating voltage and OFF current can be readily regulated by NIR illumination due to strong NIR absorption of the well‐aligned edge‐to‐edge interconnected N‐CuMe2Pc NWs and tunable potential barrier formed between active layer and Ag electrode, which are further verified by absorption spectrum and Kelvin probe force microscope analysis, respectively. This study provides a generalized method for optimizing device performance and attaching phototunable properties of organic memristive memories. In addition, compared with pristine CuPc molecules with low solubility, limitation of thermal evaporation approach that is incompatible with scaling up is expected to overcome by the solution‐processed N‐CuMe2Pc NWs.

One-Step Co-Evaporation of All-Inorganic Perovskite Thin Films with Room-Temperature Ultralow Amplified Spontaneous Emission Threshold and Air Stability.

Inorganic cesium lead halide perovskite has been successfully applied in the optoelectronic field due to its remarkable optical gain properties. Unfortunately, conventional solution-processed CsPbX3 films suffer unavoidable pinhole defects and poor surface morphology, severely limiting their performance on amplified spontaneous emission (ASE) and lasing applications. Herein, a dual-source thermal evaporation approach is explored to achieve a uniform and high-coverage CsPbX3 polycrystalline thin film. It was found that one-step co-evaporated CsPbBr3 (OC-CsPbBr3) thin films without post-annealing exhibit an ultralow ASE threshold of ∼3.3 μJ/cm2 and a gain coefficient above 300 cm-1. The coexistence of cubic and orthorhombic phases in these materials naturally form an energy cascade for the exciton transfer process, which enables rapid accumulation of excitons. Stable ASE intensity without degradation for at least 7 h is also realized from OC-CsPbBr3 thin films under continuous excitation, which is superior to that in the solution-processed CsPbBr3 thin films. Notably, a Fabry-Pérot cavity laser based on the OC-CsPbBr3 thin film is first achieved, featuring an ultralow lasing threshold (1.7 μJ/cm2) and directional output (a beam divergence of ∼3.8°). This work highlights the noteworthy optical properties of OC-CsPbBr3 thin films, leading to potential available applications in integrated optoelectronic chips.

Crystallized InBiS3 thin films with enhanced optoelectronic properties

In this paper, a one-step thermal evaporation approach was used for fabrication of indium bismuth sulphide thin films, and the synergetic effects of co-evaporation of two sources (indium granules and Bi2S3 powders) were investigated using different characterization techniques. X-ray diffraction (XRD) analysis confirmed the crystalline orthorhombic structure for the post-annealed samples. Surface roughness and crystal size of the obtained film samples were increased with increasing annealing temperatures. Analysis using X-ray photoelectron spectroscopy showed the formation of the InBiS3 structure for the obtained films, which is also confirmed by the XRD results. The optical absorption coefficient value of the annealed samples was found to be in the order of 105 cm−1 in the visible region of the solar spectrum. The optical band gap energy and electrical resistivity of the fabricated samples were observed to decrease (from 2.2 to 1.3 eV, and from 0.3 to 0.01 Ω–cm, respectively) with increasing annealing temperatures (from 200 to 350 °C), indicating the suitability of the prepared InBiS3 thin films for solar cell applications.

Ambipolar Organic Field‐Effect Transistors Based on a Dual‐Function, Ultrathin and Highly Crystalline 2,9‐didecyldinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene (C10‐DNTT) Layer

AbstractUltrathin organic semiconductor thin films have great value in the investigation of carrier transport behavior in organic field‐effect transistors (OFETs). Here, the dual solution shearing (DSS) method is adopted to deposit ultrathin and closely packed 2,9‐didecyldinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene (C10‐DNTT) films. This smooth, ultrathin and highly crystalline DSS‐processed C10‐DNTT layer can be utilized in p–n stacking bilayer ambipolar OFETs. It has two major functions in the bilayer OFET: (i) it acts as the p‐channel active layer; and (ii) it serves as the growth template of the upper n‐type semiconductor layer. The closely packed alkyl side chains of the C10‐DNTT molecules behave like long alkyl chains in the self‐assembled monolayer and can assist the packing and orientation of the following layer. The F16CuPc layer grown on DSS‐processed C10‐DNTT shows crystallized lamellae structure. The smooth C10‐DNTT surface can suppress the trap states and enhance the charge transfer between the p–n layer interface. The drain‐source current (IDS) in the p‐channel and n‐channel shows a threefold and fivefold increase compared with two‐step thermal evaporation. These findings demonstrate the potential of using solution‐processed ultrathin organic semiconductor in multilayer organic electronics, which cannot be easily achieved by the conventional thermal evaporation approach.

Ultraviolet photodetectors with high photosensitivity based on type-II ZnS/SnO2 core/shell heterostructured ribbons.

Semiconducting heterostructures with type-II band structure have attracted much attention due to their novel physical properties and wide applications in optoelectronics. Herein, we report, for the first time, a controlled synthesis of type-II ZnS/SnO2 heterostructured ribbon composed of SnO2 nanoparticles that uniformly cover the surface of ZnS ribbon via a simple and versatile thermal evaporation approach. Structural analysis indicated that the majority of SnO2 nanoparticles have an equivalent zone axis, i.e., <-313> of rutile SnO2, which is perpendicular to ±(2-1-10) facets (top/down surfaces) of ZnS ribbon. For those SnO2 nanoparticles decorated on ±(01-10) facets (side surfaces) of ZnS ribbon, an epitaxial relationship of (01-10)ZnO//(020)SnO2 and [2-1-10]ZnO//[001]SnO2 was identified. To explore their electronic and optoelectronic properties, we constructed field-effect transistors from as-prepared new heterostructures, which exhibited an n-type characteristic with an on/off ratio of ∼10(3) and a fast carrier mobility of ∼33.2 cm2 V(-1) s(-1). Owing to the spatial separation of photogenerated electron-hole pairs from type-II band alignment together with the good contacts between electrodes and ribbon, the resultant photodetector showed excellent photoresponse properties, including large photocurrent, high sensitivity (external quantum efficiency as high as ∼2.4×10(7)%), good stability and reproducibility, and relatively fast response speed. Our results suggest great potential of ZnS/SnO2 heterostructures for efficient UV light sensing, and, more importantly, signify the advantages of type-II semiconducting heterostructures for construction of high-performance nano-photodetectors.

Type-II ZnO nanorod–SnO2 nanoparticle heterostructures: characterization of structural, optical and photocatalytic properties

In this work we report, for the first time, on the preparation of ZnO nanorod-SnO2 nanoparticle (ZnO NR-SnO2 NP) heterostructures by a simple two-step thermal evaporation approach. Systematical characterization of the product reveals that the rutile SnO2 NPs, with a diameter of about 20 nm, are uniformly and tightly decorated on the entire ZnO NRs. Photoluminescence (PL) investigation on the ZnO NR-SnO2 NP heterostructures shows that they exhibit a significantly decreased UV emission compared with the bare ZnO NRs, revealing an efficient charge separation arising from the type-II band alignment. Enlightened by this merit, photocatalytic behavior of the synthesized heterostructures is studied, which shows a remarkably enhanced photodegradation performance of rhodamine B (RhB) in contrast to the pure ZnO NRs. We also carry out the stability test of the ZnO NR-SnO2 NP heterostructures and the result indicates an extremely high adhesion nature between the ZnO NR and the coated SnO2 NPs. This advantage endowed with the thermal evaporation approach can lead to an efficient spatial charge separation between the ZnO NR and the SnO2 NPs and thus effectively minimize the charge recombination along three-dimensional heterointerfaces, which makes such ZnO NR-SnO2 NP architectures highly promising for a wide range of photovoltaic and photocatalytic applications.

Germanium–graphene composite anode for high-energy lithium batteries with long cycle life

The high-energy lithium ion battery is an ideal power source for electric vehicles and grid-scale energy storage applications. Germanium is a promising anode material for lithium ion batteries due to its high specific capacity, but still suffers from poor cyclability. Here, we report a facile preparation of a germanium–graphene nanocomposite using a low-pressure thermal evaporation approach, by which crystalline germanium particles are uniformly deposited on graphene surfaces or embedded into graphene sheets. The nanocomposite exhibits a high Coulombic efficiency of 80.4% in the first cycle and a capacity retention of 84.9% after 400 full cycles in a half cell, along with high utilization of germanium in the composite and high rate capability. These outstanding properties are attributed to the monodisperse distribution of high-quality germanium particles in a flexible graphene framework. This preparation approach can be extended to other active elements that can be easily evaporated (e.g., sulfur, phosphorus) for the preparation of graphene-based composites for lithium ion battery applications.

Synthesis of ZnO nanostructure films by thermal evaporation approach and their application in dye-sensitized solar cells

Zinc oxide (ZnO) films were prepared successfully by simple thermal evaporation of zinc acetate dihydrate at low temperature onto FTO (fluorine-doped tin oxide) glass substrates coated with thin ZnO seed layer. The synthetic parameter such as temperature was found to determine the morphology of nanostructures. ZnO nanorod (NR) and nanoparticle (NP) films have been synthesized at 245 and 350°C, respectively, for 6h. The dye-sensitized solar cells (DSSCs) were fabricated using the ZnO nanostructure films as photosensitized electrodes. A maximum photoelectric conversion efficiency (PCE) of 1.56%, and short-circuit photocurrent density of 5.12mA/cm2 were achieved with the ZnO NP-based DSSC. The PCE increase was ascribed to the reduced recombination loss and prolonged electron lifetime according to electrochemical impedance spectroscopy (EIS).

Asymmetric light propagation in composition-graded semiconductor nanowires

Asymmetric light propagation is crucial to the development of optical-based functional components in nanophotonics. Diverse configurations and structures have been proposed to allow asymmetrical propagation of photonic signal, but on-chip integration is difficult to achieve due to their complex structure and/or relatively large footprint. Here we report the first design and realization of asymmetric light propagation in single semiconductor nanowires with a composition gradient along the length. We show the asymmetric nanowire waveguides can be synthesized using a simple thermal evaporation and vapor transport approach without involving complicated and costly fabrication processes. Our studies demonstrate the asymmetric nanowire waveguides offer some significant advantages over previous designs, including ultra-low operation power, tunable working wavelength and nanoscale footprint, making them attractive building blocks for integrated photonic circuits.