Deposited Tin Oxide Research Articles

Enhancing UV photodetection sensitivity via pulsed laser optimization in SnO2: WO3/Si nanostructures

Abstract This manuscript investigates the deposition of tin oxide (SnO2) doped tungsten trioxide (WO3) films on silicon (Si) substrate using pulsed laser deposition technique (PLD) for ultraviolet (UV) photodetection. The structural, optical, morphological, electric, and photodetector properties of SnO2 doped WO3 films were extensively investigated. The optical characteristics, using UV-Vis spectroscopy, reveals a tunable optical band gap ranging from 2.85 eV to 2.25 eV with increasing laser energy, which is consistent with the findings obtained from photoluminescence (PL) analysis. Raman spectroscopy demonstrates three vibration modes at 319.80, 603.30, and 866.20 cm-1. Field emission scanning electron microscopy (FESEM) images displayed spherical nanoparticles with average diameters of 43.90, 47.55, and 62.20 nm for 140, 180, and 220 mJ, respectively. Atomic force microscopy (AFM) measurements indicate an increase in the thin film grain size, roughness surface, and root mean square at higher laser energies (140, 180 and 220 mJ). Under illumination condition, the photodetector gives a considerable photocurrent amount (0.5 mA), which increases with higher laser energies. The proposed geometry demonstrates an excellent photo-response within the wavelength range of 350 to 550 nm, mainly at 420 nm. The optimized device illuminated with laser energy of 220 mJ exhibits a response and recovery time of 352 ms and 737 ms, respectively, highlighting its potential for efficient and responsive applications.

Long-term stability in perovskite solar cells through atomic layer deposition of tin oxide.

Robust contact schemes that boost stability and simplify the production process are needed for perovskite solar cells (PSCs). We codeposited perovskite and hole-selective contact while protecting the perovskite to enable deposition of SnOx/Ag without the use of a fullerene. The SnOx, prepared through atomic layer deposition, serves as a durable inorganic electron transport layer. Tailoring the oxygen vacancy defects in the SnOx layer led to power conversion efficiencies (PCEs) of >25%. Our devices exhibit superior stability over conventional p-i-n PSCs, successfully meeting several benchmark stability tests. They retained >95% PCE after 2000 hours of continuous operation at their maximum power point under simulated AM1.5 illumination at 65°C. Additionally, they boast a certified T97 lifetime exceeding 1000 hours.

Aromatic carboxyl acid regulated nanoparticle deposition and passivation of tin oxide for high performance perovskite solar cells

The composition and nano particle agglomeration of hydrolyzed species in chemical bath deposition (CBD) plays a key role in obtaining efficient SnO2 film for high performance perovskite solar cells (PSCs). In this work, the aromatic acids with varied carboxyl groups were investigated to regulate the nano particle deposition and passivate the buried SnO2/perovskite interface. The quasi in-situ dynamic light scattering and Zeta potential results indicated that the nano particle agglomeration with trimesic acid (TMA) was significantly refined throughout the whole deposition process. The TMA-SnO2 achieved an ideal energy band alignment with perovskite and released the internal residual strain, promoting the growth and crystallization of the perovskite film due to the corrdination of carboxyl groups. As a result, the interface defects were effectively passivated with enhanced efficiency and stability. The small area device based on TMA-SnO2 obtained an efficiency of 25.07 %. The devices with an enlarged area of 1.4 cm2 and the 5x5 cm2 mini-module (active area 10.054 cm2) showed impressive PCEs of 23.93 % and 22.40 %, respectively. Furthermore, the unencapsulated devices exhibit enhanced long-term stability, maintaining 80 % and 90 % of the initial efficiencies under 80 ± 5°C thermal annealing in nitrogen for 1176 h and in air condition for 3224 h, respectively.

Investigations on temperature dependent properties of spray deposited tin oxide thin films

The present study reported the temperature dependent properties of tin oxide (SnO2) thin films deposited by using conventional, cost effective and non-vacuum-based spray pyrolysis technique (SPT). The as deposited films were characterized by various characterization techniques such as X ray diffraction (XRD), UV-Vis spectroscopy and Scanning electron microscopy (SEM) to study their structural, optical and morphological properties respectively. XRD analysis revealed tetragonal rutile crystal structure of SnO2 with preferred orientation along (200) plane. The refinement of XRD data was also carried out by Rietveld refinement to obtain the fitting parameters, crystallite size and lattice parameters. UV-Vis study showed considerable change in optical absorbance and transmittance with change in substrate temperature. Effect of substrate temperature on film thickness, refractive index and band gap energy were determined by Swanepoel method and by Tauc’s plot respectively. The Urbach energy was also calculated and were correlated to the defects in SnO2 films. SEM micrograph showed the transformation from granules to nanospheres as a function of substrate temperature. Electrical properties were determined by Hall effect measurements which gives carrier concentration, electrical resistivity and mobility in the order of 1019-1020 /cm3, 10−2-10−3 Ω.cm and 4–23 cm2/Vs respectively.

Surface Engineering of Perovskite Single Crystals by Atomic Layer Deposited Tin Oxide for Optical Communication.

Perovskite single crystals with excellent physical properties have broad prospects in the field of optoelectronics. However, the presence of dangling bonds, surface dislocations, and chemical impurities results in high surface defect density and sensitivity to humidity. Unfortunately, there are relatively few surface engineering strategies for single perovskite single crystals. We present a strategy utilizing atomic layer deposited SnOx to passivate surface defects in perovskite single crystals. The photodetector prepared based on the modified FAPbBr3 single crystals exhibits a low dark current of 1.89 × 10-9 A at a 5 V bias, close to 4 times lower with respect to the pristine device, a high detectivity of 2.3 × 1010 jones, and a fast response time of 27 μs. Moreover, the photodetectors feature long-term operational stability because the presence of a dense SnOx capping layer hinders the ingress of moisture and diffusion of ions. We further demonstrate the promise of our perovskite single crystal detectors for real-time subaqueous optical communication.

Unveiling and Overcoming Instabilities in Perovskite Solar Cells Induced by Atomic‐Layer‐Deposition Tin Oxide

Atomic layer deposition of tin oxide (ALD–SnOx) has emerged as a promising buffer/protection layer, often replacing bathocuproine (BCP) in applications such as semitransparent and tandem devices. However, the long‐term stability and underlying degradation mechanisms of perovskite solar cells (PSC) incorporating ALD–SnOx remain elusive. Herein, the long‐term stability of PSCs featuring an ALD–SnOx buffer layer is systematically investigated. Intriguingly, it is observed that cells with ALD–SnOx exhibit heightened susceptibility to severe degradation, surpassing even the degradation levels observed with BCP under humid conditions. Through an extensive analysis employing X‐ray photoelectron spectroscopy and X‐ray diffraction, it is unveiled that ALD–SnOx triggers a phase transition in the perovskite when exposed to moisture, transitioning from the black cubic phase to the yellow delta phase, despite the presence of a thin layer of fullerene between the SnOx and the perovskite. Replacing ALD–SnOx with ALD–AlOx as a buffer layer emerges as a transformative strategy, effectively bolstering the humidity and thermal stability of the cells, without affecting device efficiency. The optimized ALD–AlOx‐buffered device exhibits a high efficiency of 24.61% and maintains 88% of its initial efficiency after maximum power point tracking under 1 sun illumination for 1350 h at 65 °C in ambient air when encapsulated.

Rational Design of a Chemical Bath Deposition Based Tin Oxide Electron-Transport Layer for Perovskite Photovoltaics.

Chemical bath deposition (CBD) is widely used to deposit tin oxide (SnOx ) as an electron-transport layer in perovskite solar cells (PSCs). The conventional recipe uses thioglycolic acid (TGA) to facilitate attachments of SnOx particles onto the substrate. However, nonvolatile TGA is reported to harm the operational stability of PSCs. In this work, a volatile oxalic acid (OA) is introduced as an alternative to TGA. OA, a dicarboxylic acid, functions as a chemical linker for the nucleation and attachment of particles to the substrate in the chemical bath. Moreover, OA can be readily removed through thermal annealing followed by a mild H2 O2 treatment, as shown by FTIR measurements. Synergistically, the mild H2 O2 treatment selectively oxidizes the surface of the SnOx layer, minimizing nonradiative interface carrier recombination. EELS (electron-energy-loss spectroscopy) confirms that the SnOx surface is dominated by Sn4+ , while the bulk is a mixture of Sn2+ and Sn4+ . This rational design of a CBD SnOx layer leads to devices with T85 ≈1500h, a significant improvement over the TGA-based device with T80 ≈250h. The champion device reached a power conversion efficiency of 24.6%. This work offers a rationale for optimizing the complex parameter space of CBD SnOx to achieve efficient and stable PSCs.

Semitransparent Perovskite Solar Cells with Ultrathin Protective Buffer Layers.

Semitransparent perovskite solar cells (ST-PSCs) are increasingly important in a range of applications, including top cells in tandem devices and see-through photovoltaics. Transparent conductive oxides (TCOs) are commonly used as transparent electrodes, with sputtering being the preferred deposition method. However, this process can damage exposed layers, affecting the electrical performance of the devices. In this study, an indium tin oxide (ITO) deposition process that effectively suppresses sputtering damage was developed using a transition metal oxides (TMOs)-based buffer layer. An ultrathin (<10 nm) layer of evaporated vanadium oxide or molybdenum oxide was found to be effective in protecting against sputtering damage in ST-PSCs for tandem applications, as well as in thin perovskite-based devices for building-integrated photovoltaics. The identification of minimal parasitic absorption, the high work function and the analysis of oxygen vacancies denoted that the TMO layers are suitable for use in ST-PSCs. The highest fill factor (FF) achieved was 76%, and the efficiency (16.4%) was reduced by less than 10% when compared with the efficiency of gold-based PSCs. Moreover, up-scaling to 1 cm2-large area ST-PSCs with the buffer layer was successfully demonstrated with an FF of ∼70% and an efficiency of 15.7%. Comparing the two TMOs, the ST-PSC with an ultrathin V2Ox layer was slightly less efficient than that with MoOx, but its superior transmittance in the near infrared and greater light-soaking stability (a T80 of 600 h for V2Ox compared to a T80 of 12 h for MoOx) make V2Ox a promising buffer layer for preventing ITO sputtering damage in ST-PSCs.

Ionic Liquid-Mediated Route to Atomic Layer Deposition of Tin(II) Oxide via a C-C Bond Cleavage Ligand Modification Mechanism.

Atomic layer deposition (ALD) is a technologically important method to grow thin films with high conformality and excellent thickness control from vapor phase precursors. The development of new thermal ALD processes can be limited by precursor reactivity and stability: reaction temperature and precursor design are among the few variables available to achieve higher reactivity in gas-phase reactions, unlike in solution synthesis, where the use of solvent and/or a catalyst can promote a desired reaction. To bridge this synthesis gap between vapor-phase and solution-phase, we demonstrate the use of an ultrathin coating layer of a vapor phase-compatible solvent─an ionic liquid (IL)─on our growth substrate to perform ALD of SnO. Successful SnO deposition is achieved using tin acetylacetonate and water, a process that otherwise would require a stronger counter-reactant such as ozone. The presence of the layer of IL allows a solvent-mediated reaction mechanism to take place on the growth substrate surface. We report a growth per cycle of 0.67 Å/cycle at a deposition temperature of 100 °C in an IL comprising 1-ethyl-3-methylimidazolium hydrogen sulfate. Characterization of the ALD films confirms the SnO film composition, and 1H and 13C NMR are used to probe the solvent-mediated ALD reaction, suggesting a solvent-mediated addition-elimination-type mechanism which breaks a C-C bond in acetylacetonate to form acetone and acetate. Density functional theory calculations show that the IL solvent is beneficial to the proposed solvent-mediated mechanism by lowering the C-C bond cleavage energetics of acetylacetonate compared to the vapor phase. A general class of ligand modification reactions for thermal ALD is thus introduced in this work.

Ultra-Thin SnOx Buffer Layer Enables High-Efficiency Quantum Junction Photovoltaics.

Solution-processed solar cells are promising for the cost-effective, high-throughput production of photovoltaic devices. Colloidal quantum dots (CQDs) are attractive candidate materials for efficient, solution-processed solar cells, potentially realizing the broad-spectrum light utilization and multi-exciton generation effect for the future efficiency breakthrough of solar cells. The emerging quantum junction solar cells (QJSCs), constructed by n- and p-type CQDs only, open novel avenue for all-quantum-dot photovoltaics with a simplified device configuration and convenient processing technology. However, the development of high-efficiency QJSCs still faces the challenge of back carrier diffusion induced by the huge carrier density drop at the interface of CQDs and conductive glass substrate. Herein, an ultra-thin atomic layer deposited tin oxide (SnOx ) layer is employed to buffer this carrier density drop, significantly reducing the interfacial recombination and capacitance caused by the back carrier diffusion. The SnOx -modified QJSC achieves a record-high efficiency of 11.55% and a suppressed hysteresis factor of 0.04 in contrast with reference QJSC with an efficiency of 10.4% and hysteresis factor of 0.48. This work clarifies the critical effect of interfacial issues on the carrier recombination and hysteresis of QJSCs, and provides an effective pathway to design high-performance all-quantum-dot devices.

Photocatalytic Performance Test of Sn&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;/TiO&lt;sub&gt;2&lt;/sub&gt;/SiO&lt;sub&gt;2&lt;/sub&gt; Particles with Adjusted Sn&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; Deposition under Indoor Environment

Photocatalyst is a material that can not only generate clean energy for the environment but can also be used in various applications such as antibacterial and antifouling properties. In this study, we compared the photocatalytic performance of titanium dioxide under indoor conditions by adjusting the amount of tin oxide attached to it. The amount of tin oxide deposited can be varied by adjusting the hydrothermal synthesis time. Appropriate tin oxide deposition recorded higher performance than excessive tin oxide deposition in both the yeast antimicrobial test and the water-splitting power generation test.

Low‐Temperature, Scalable, Reactive Deposition of Tin Oxide for Perovskite Solar Cells

Perovskite Solar Cells In article number 2200263, David George Lidzey and co-workers fabricated SnOx electron-extraction layers via a reactive electron-beam evaporation process from a metal source under a partial pressure of oxygen. These are then used in standard (n-i-p) architecture perovskite solar cells and achieve power conversion efficiencies up to 19.3%. The SnOx deposition process is performed onto substrates maintained at low temperature compared to similar techniques, with films not requiring any subsequent high-temperature post-deposition annealing. This demonstrates the potential compatibility of reactive electron-beam evaporation with roll-to-roll processing onto flexible polymeric substrates.

Low‐Temperature, Scalable, Reactive Deposition of Tin Oxide for Perovskite Solar Cells

Tin oxide (SnO x ) electron‐extraction layers are fabricated via a reactive electron‐beam evaporation process from a metal source under a partial pressure of oxygen. These are then used in standard (n‐i‐p) architecture perovskite solar cells and achieve power conversion efficiencies up to 19.3%. The SnO x deposition process is performed onto substrates maintained at low temperature compared to similar techniques, with films not requiring any subsequent high‐temperature post‐deposition annealing. This demonstrates the potential compatibility of reactive electron‐beam evaporation with roll‐to‐roll processing onto flexible polymeric substrates.

Understanding on the hydrogen detection of plasma sprayed tin oxide/tungsten oxide (SnO2/WO3) sensor

The plasma spray technique was well proven in producing metal oxide based gas sensors in the last two decades using different powder feedstocks. However, limited research was made to fabricate hydrogen gas sensor from tin oxide layer coated over tungsten oxide layer. This paper attempts to interpret the hydrogen gas sensing performances of plasma sprayed coating derived by depositing tin oxide layer over tungsten oxide (SnO2/WO3) layer. Plasma sprayed SnO2/WO3 sensor showed maximum response of 90% at 150 °C in contrast to stand-alone WO3 (89% at 350 °C) and stand-alone SnO2 (89% at 250 °C). The lower operating temperature of SnO2/WO3 sensor without compromising gas response was attributed to the WO3–SnO2 hetero-junction. SnO2/WO3 sensor showed selective sensing towards hydrogen with respect to carbon monoxide and methane gases. This sensor also possessed repeatable characteristics after 39 days from the initial measurement. In a nut-shell, plasma spayed SnO2/WO3 sensor showed stability of base resistance, repeatability after successive response and recovery cycles, selective sensing towards 500 ppm H2 with significant magnitude of gas response of 90%, response time of 35 s and recovery time of 269 s at a temperature of 150 °C.

Industrially Compatible Fabrication Process of Perovskite-Based Mini-Modules Coupling Sequential Slot-Die Coating and Chemical Bath Deposition.

To upscale the emerging perovskite photovoltaic technology to larger-size modules, industrially relevant deposition techniques need to be developed. In this work, the deposition of tin oxide used as an electron extraction layer is established using chemical bath deposition (CBD), a low-cost and solution-based fabrication process. Applying this simple low-temperature deposition method, highly homogeneous SnO2 films are obtained in a reproducible manner. Moreover, the perovskite layer is prepared by sequentially slot-die coating on top of the n-type contact. The symbiosis of these two industrially relevant deposition techniques allows for the growth of high-quality dense perovskite layers with large grains. The uniformity of the perovskite film is further confirmed by scanning electron microscopy (SEM)/scanning transmission electron microscopy (STEM) analysis coupled with energy dispersive X-ray spectroscopy (EDX) and cathodoluminescence measurements allowing us to probe the elemental composition at the nanoscale. Perovskite solar cells fabricated from CBD SnO2 and slot-die-coated perovskite show power conversion efficiencies up to 19.2%. Furthermore, mini-modules with an aperture area of 40 cm2 demonstrate efficiencies of 17% (18.1% on active area).

Batch chemical bath deposition of large-area SnO2 film with mercaptosuccinic acid decoration for homogenized and efficient perovskite solar cells

Chemical bath deposited tin oxide film (CBD SnO2) has been demonstrated as an amazing electron transporting layer for high photoconversion efficiency (PCE) hybrid perovskite solar cells (PSCs) over 25 %. The current CBD process is normally studied for small area devices. A rapid batch production of large-area CBD SnO2 film with high and uniform performance is essential for potential upscaling of perovskite solar module. Herein, we carried out a modified batch CBD process, a double chemical bath deposition (DC), for batch fabrication of large-area (400 cm2) SnO2 films and realized a homogenized PCE with a variance (Va) of 0.127, comparing to that of control sample of Va at 2.833. We further introduced mercaptosuccinic acid (MSA) at the interface of SnO2/perovskite for convenient energy band alignment and defects passivation, which significantly improved the PCE, stability and homogeneity of the devices. As a result, the mix-cation planar PSCs reaches 21.24% with further reduced Va of 0.073. A high efficiency of 22.54% was obtained for the narrow band gap FA-based perovskite device. These results suggest high potential of this modified CBD route for large area and high efficiency perovskite module preparation.

Influence of thermal cycling on the optical and the electrical properties of atmospheric pressure chemical vapor deposited tin oxide films grown using water and methanol vapors as oxidizers

Tin oxide films were chemically vapor deposited at atmospheric pressure at temperatures near 400 °C using SnCl4 as metal precursor and water or methanol vapors as oxidizers. The optical and electrical properties of these films were studied with spectroscopic ellipsometry (SE) and resistivity measurements while morphology and structure by scanning electron microscopy (SEM) and x-ray diffraction (XRD) measurements. It was found that both kinds of samples exhibited granular morphology with grain sizes of 10 and 80-100 nm for water and methanol deposited samples respectively. The crystallographic orientation of grains was similar for both kinds of samples. SE and resistivity measurements were simultaneously performed on samples up to 400 °C in air and at two thermal cycles. Using the Tauc-Lorentz combined with the Drude physical models the refractive index (real and imaginary parts) and the Tauc gap of samples were extracted from the SE measurements. Films morphology proved to be the decisive factor that governs optical and electrical properties of SnO2 films. So, large gained methanol vapor deposited SnO2 films were more than 80% transparent within the visible and an order of magnitude more conductive (resistivity of the order of 9-10 mΩ.cm) than the water deposited small-grained ones. It was also found that thermal cycling causes slight atomic re-arrangements in films that are invisible in XRD and SEM measurements but which influence significantly their optical and electrical properties.

Low temperature open-air plasma deposition of amorphous tin oxide for perovskite solar cells

A low-temperature, open-air plasma process to deposit amorphous SnOx thin films as an electron-transport layer in a planar-heterojunction n−i−p perovskite solar cell is reported. Open-air plasma processing is a scalable, low capital expenditure technique capable of manufacturing-scale production without enclosures or vacuum pumps. The technique provides flexibility to tune SnOx film composition and properties by adjusting several easily accessible processing parameters. In this study, we demonstrate large area SnOx thin film deposition on substrates up to 100 cm2. The SnOx films are deposited using monobutyltin trichloride as the chemical precursor and formed without any post-annealing, which has the potential for lowering costs as an in-line process. The film exhibits low surface roughness, excellent optical transmission of greater than 90 % across the visible regime, and low electrical resistivity of 13.3 Ω*m, which is multiple orders of magnitude lower than previously reported values of amorphous SnO2 thin films. The film is then incorporated into a planar perovskite solar cell with a power conversion efficiency of 11.8 %. These factors suggest that open-air plasma-deposited SnOx thin films can potentially be compatible with low-cost and large-scale fabrication of organohalide lead perovskite solar cells and modules.

Origin of Mangetotransport Properties in APCVD Deposited Tin Oxide Thin Films.

Transparent conducting oxides (TCO) with high electrical conductivity and at the same time high transparency in the visible spectrum are an important class of materials widely used in many devices requiring a transparent contact such as light-emitting diodes, solar cells and display screens. Since the improvement of electrical conductivity usually leads to degradation of optical transparency, a fine-tuning sample preparation process and a better understanding of the correlation between structural and transport properties is necessary for optimizing the properties of TCO for use in such devices. Here we report a structural and magnetotransport study of tin oxide (SnO2), a well-known and commonly used TCO, prepared by a simple and relatively cheap Atmospheric Pressure Chemical Vapour Deposition (APCVD) method in the form of thin films deposited on soda-lime glass substrates. The thin films were deposited at two different temperatures (which were previously found to be close to optimum for our setup), 590 °C and 610 °C, and with (doped) or without (undoped) the addition of fluorine dopants. Scanning Electron Microscopy (SEM) and Grazing Incidence X-ray Diffraction (GIXRD) revealed the presence of inhomogeneity in the samples, on a bigger scale in form of grains (80–200 nm), and on a smaller scale in form of crystallites (10–25 nm). Charge carrier density and mobility extracted from DC resistivity and Hall effect measurements were in the ranges 1–3 × 1020 cm−3 and 10–20 cm2/Vs, which are typical values for SnO2 films, and show a negligible temperature dependence from room temperature down to −269 °C. Such behaviour is ascribed to grain boundary scattering, with the interior of the grains degenerately doped (i.e., the Fermi level is situated well above the conduction band minimum) and with negligible electrostatic barriers at the grain boundaries (due to high dopant concentration). The observed difference for factor 2 in mobility among the thin-film SnO2 samples most likely arises due to the difference in the preferred orientation of crystallites (texture coefficient).

Controller of fluorine­doped tin oxide thin films deposition via cycles and annealing temperatures by spin coating techniques

Fluorine-doped tin oxide (FTO) thin films have been deposited by the modified spin coating method at 3000 rpm using tin (II) chloride dehydrate (SnCl 2 ×2H 2 O) as a precursor, ammonium fluoride (NH 4 F) as a dopant and ethanol as a solvent. The aim of this research is to find out the quality of the thin film based on the number of cycles (3, 4, 5, and 6 cycles) and annealing temperature (300, 400 and 500 °C). The variation of annealing temperature and number of cycles can affect the crystal structure of the FTO thin film, crystal size and grain size. Increasing the number of cycles and annealing temperature can lead to larger crystallite size and lower dislocation density, so that electrons between the grains can move easily. The large grain can reduce the grain boundary, increasing the electron mobility and decreasing the resistivity. XRD analysis shows that the structure of SnO 2 polycrystalline with the most dominant crystal plane (110) is formed in this research when compared to the intensity of other structures. The resistivity value decreases with increasing the annealing temperature and number of cycles. In addition, transparency value also decreases along with increasing the annealing temperature and number of cycles. The optimum results of resistivity and transparency values obtained in this research are 1.692´10 -2 Ω×cm and 69.232 % at 500 °C and 5 cycles. These results can be used as a reference for further study to optimize the production of fluorine-doped tin oxide (FTO) thin film with spin coating. Therefore, many factors that affect the production of fluorine-doped tin oxide (FTO) thin film, either dissolving stage or deposition process on the substrate surface still need to be studied deeply to obtain the optimum result