Single Source Thermal Evaporation 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.

Surface Passivation for Promotes Bi-Excitonic Amplified Spontaneous Emission in CsPb(Br/Cl)3 Perovskite at Room Temperature.

Perovskite-type lead halides exhibit promising performances in optoelectronic applications, for which lasers are one of the most promising applications. Although the bulk structure has some advantages, perovskite has additional advantages at the nanoscale owing to its high crystallinity given by a lower trap density. Although the nanoscale can produce efficient light emission, its comparatively poor chemical and colloidal stability limits further development of devices based on this material. Nevertheless, bulk perovskites are promising as optical amplifiers. There has been some developmental progress in the study of optical response and amplified spontaneous emission (ASE) as a benchmark for perovskite bulk phase laser applications. Therefore, to achieve high photoluminescence quantum yields (PLQYs) and large optical gains, material development is essential. One of the aspects in which these goals can be achieved is the incorporation of a bulk structure of high-quality crystallization films based on inorganic perovskite, such as cesium lead halide (CsPb(Br/Cl)3), in polymethyl methacrylate (PMMA) polymer and encapsulation with the optimal thickness of the polymer to achieve complete surface coverage, prevent degradation, surface states, and surface defects, and suppress emission at depth. Sequential evaporation of the perovskite precursors using a single-source thermal evaporation technique (TET) effectively deposited two layers. The PL and ASEs of the bare and modified films with a thickness of 400 nm PMMA were demonstrated. The encapsulation layer maintained the quantum yield of the perovskite layer in the air for more than two years while providing added optical gain compared to the bare film. Under a picosecond pulse laser, the PL wavelength of single excitons and ASE wavelength associated with the stimulated decay of bi-excitons were achieved. The two ASE bands were highly correlated and competed with each other; they were classified as exciton and bi-exciton recombination, respectively. According to the ASE results, bi-exciton emission could be observed in an ultrastable CsPb(Br/Cl)3 film modified by PMMA with a very low excitation energy density of 110 µJ/cm2. Compared with the bare film, the ASE threshold was lowered by approximately 5%. A bi-exciton has a binding energy (26.78 meV) smaller than the binding energy of the exciton (70.20 meV).

Inorganic and lead-free CsBi3I10 thin-film solar cell prepared by single-source thermal evaporation

All inorganic lead-free halide perovskites have attracted much attention due to their non-toxic and suitable bandgap. In this paper, we first prepared all inorganic lead-free perovskite CsBi3I10 thin-films by single-source thermal evaporation deposition. The results show that CsBi3I10 thin films prepared by single-source thermal evaporation have layered structure, high purity hexagonal phase and high crystallinity, which are consistent with the theoretical calculation results. The surface of the thin film was compact and uniform, and had high homology with the crystal structure of the evaporation source material. After annealing, the crystallinity of the film was further improved. The photovoltaic conversion efficiency of perovskite solar cells based on the CsBi3I10 thin film is as high as 0.84%. These results indicate that the proposed single-source thermal evaporation method has the potential to prepare high efficiency inorganic lead-free perovskite solar cells.

Single-Source Thermal Evaporation Growth and the Tuning Surface Passivation Layer Thickness Effect in Enhanced Amplified Spontaneous Emission Properties of CsPb(Br0.5Cl0.5)3 Perovskite Films.

High-quality inorganic cesium lead halide perovskite CsPb(Br0.5Cl0.5)3 thin films were successfully achieved through evaporation of the precursors and deposition sequentially by a single-source thermal evaporation system. The different melting points of the precursors were enabled us to evaporate precursors one by one in one trip. The resulting films through its fabrication were smooth and pinhole-free. Furthermore, this technique enabled complete surface coverage by high-quality perovskite crystallization and more moisture stability oppositely of that produce by solution-processed. Then the perovskite films were encapsulated by evaporated a polymethyl methacrylate (PMMA) polymer as a specialized surface passivation approach with various thicknesses. The blue emission, high photoluminescence quantum yield (PLQY), stable, and low threshold of amplified spontaneous emission (ASE) properties of CsPb(Br0.5Cl0.5)3 films in the bulk structure at room temperature were achieved. The effects of the surface-passivation layer and its thickness on the optical response were examined. Detailed analysis of the dependence of ASE properties on the surface passivation layer thickness was performed, and it was determined this achieves performance optimization. The ASE characteristics of bare perovskite thin film were influenced by the incorporation of the PMMA with various thicknesses. The improvement to the surface layer of perovskite thin films compared to that of the bare perovskite thin film was attributed to the combination of thermal evaporation deposition and surface encapsulation. The best results were achieved when using a low PMMA thickness up to 100 nm and reducing the ASE threshold by ~11 μJ/cm2 when compared with free-encapsulation and by ~13 μJ/cm2 when encapsulation occurs at 200 nm or thicker. Compared to the bare CsPb(Br0.5Cl0.5)3, ASE reduced 1.1 times when the PMMA thickness was 100 nm.

Single Source Thermal Evaporation of Two-dimensional Perovskite Thin Films for Photovoltaic Applications

Hybrid two-dimensional (2D) halide perovskites has been widely studied due to its potential application for high performance perovskite solar cells. Understanding the relationship between microstructural and opto-electronic properties is very important for fabricating high-performance 2D perovskite solar cell. In this work, the effect of solvent annealing on grain growth was investigated to enhance the efficiency of photovoltaic devices with 2D perovskite films based on (BA)2(MA)3Pb4I13 prepared by single-source thermal evaporation. Results show that solvent annealing with the introduction of solvent vapor can effectively enhance the crystallization of the (BA)2(MA)3Pb4I13 thin films and produce denser, larger-crystal grains. The thin films also display a favorable band gap of 1.896 eV, which benefits for increasing the charge-diffusion lengths. The solvent-annealed (BA)2(MA)3Pb4I13 thin-film solar cell prepared by single-source thermal evaporation shows an efficiency range of 2.54–4.67%. Thus, the proposed method can be used to prepare efficient large-area 2D perovskite solar cells.

High-performance bismuth telluride thermoelectric thin films fabricated by using the two-step single-source thermal evaporation

Bismuth telluride (Bi2Te3) is an efficient thermoelectric material, and fabricating Bi2Te3 thin films with good thermoelectric properties is a prerequisite to realizing the potential of these materials in microdevice application. Controllable content deposition and low-negative thermal treatment are the two main challenges in preparing high-performance thin films. In this study, stoichiometric Bi2Te3 thin films were successfully fabricated via the two-step thermal vapor process with a single evaporation source. Then, the rapid thermal process, which could avoid component loss, was used to further improve the crystallinity and thermoelectric properties of thin films. The Seebeck coefficient of Bi2Te3 thin films clearly increased after rapid heat treatment, leading to enhanced power factor and good flexibility. Such thin films exhibited low thermal conductivity due to their nano-sized grains, resulting in high ZT of flexible Bi2Te3 thin films.

High-Quality Perovskite CH₃NH₃PbI₃ Thin Films for Solar Cells Prepared by Single-Source Thermal Evaporation Combined with Solvent Treatment.

In this work, solvent annealing process for CH3NH3PbI3 thin film prepared by single source evaporation was reported. Characterized by the scanning electron microscope (SEM), X-ray diffractometer (XRD), energy dispersive spectroscope (EDS), ultraviolet-visible (UV) spectrophotometer, and the photoluminescence (PL) spectrometer, our method ensured higher quality film with crystallinity, composition, well-defined grain structure, and reproducibility. The optimized solar cell device based on the structure of ITO/PEDOT:PSS/CH3NH3PbI3/PCBM/Ag achieved better performance in power conversion efficiency from 2.64% to 9.92%, providing an effective method to optimize the quality of perovskite film for solar cell application.

The influence of Ag doping and annealing on phase, structural and carrier transport characteristics of CIS thin films

Abstracts The un-doped and Ag-CIS thin films were deposited on quartz glass substrates by single source thermal evaporation method. Then, some CIS films were annealed in vacuum or N2 atmosphere from 350 °C to 550 °C. The results of XRD patterns showed the phase compositions of CIS thin films were changed with the increase of annealing temperature. Meanwhile, the results of Raman measurement confirmed a dramatic transition from CA phase to CH phase. Furthermore, the Ag atoms could promote the recrystallization process and the transition from CA phase to CH phase, which might result in the improvement of optical-electrical properties of CIS film. The transient photocurrent of the CIS-3 sample annealed at 450 °C was higher than those of other samples, which might be related to the good crystal quality. The results of I-V curves confirmed the N-type conduction of CIS-3 films, which was consistent with the results of EDS measurement. The C-V results of CIS-2 films also were the same as the results of EDS measurement. Furthermore, for the CIS-2 samples, with increase of annealing temperature, the change of conduction type may be related to the S element volatilization under vacuum situation and the decomposition of the substitutional defects AgIn.

Highly Uniform Large-Area (100 cm2) Perovskite CH3NH3PbI3 Thin-Films Prepared by Single-Source Thermal Evaporation

In this work, we report the reproducible preparation method of highly uniform large-area perovskite CH3NH3PbI3 thin films by scalable single-source thermal evaporation with the area of 100 cm2. The microstructural and optical properties of large-area CH3NH3PbI3 thin films were investigated. The dense, uniform, smooth, high crystallinity of large-area perovskite thin film was obtained. The element ratio of Pb/I was close to the ideal stoichiometric ratio of CH3NH3PbI3 thin film. These films show a favorable bandgap of 1.58 eV, long and balanced carrier-diffusion lengths. The CH3NH3PbI3 thin film perovskite solar cell shows a stable efficiency of 7.73% with almost no hysteresis, indicating a single-source thermal evaporation that is suitable for a large area perovskite solar cell.

Microstructural and optical properties of HC(NH2)2PbI3 thin films prepared by single source thermal evaporation

The HC(NH2)2PbI3 thin films as the perovskite solar cells absorption layer were prepared by single-source thermal evaporation. The stoichiometric ratio effects of HC(NH2)2I/PbI2 precursors on the properties of HC(NH2)2PbI3 thin films were investigated. The microstructure, surface morphology and optical properties of HC(NH2)2PbI3 thin films were characterized by X-ray diffraction (XRD), energy dispersive spectroscope, scanning electron microscopy and spectrophotometer respectively. The results show that, with stoichiometric ratio of FAI/PbI2 3:1, the XRD results of formamidine lead iodine thin films prepared by single source thermal evaporation indicated the typical peaks of HC(NH2)2PbI3 thin films with few impurities. The dense and uniform films were formed with large crystal grains on the surface and high crystallization. The Pb/I element ratio was approximate to the ideal stoichiometric ratio of HC(NH2)2PbI3 thin films. The band gap of the HC(NH2)2PbI3 thin film calculated was 1.5 eV, which satisfied the optical properties requirement of absorbers for perovskite solar cell applications, making them potential applicable for large-area efficient perovskite solar cells.

Substrate temperature dependence of structural, morphological and optical properties of Sn4Sb6S13 thin films deposited by vacuum thermal evaporation

In this work, structural and morphological properties of Sn4Sb6S13 thin films grown by single source thermal evaporation were investigated. The films were deposited onto glass substrates heated in the temperature range 30–200°C then characterized by XRD, AFM, SEM and Raman spectroscopy. The films are preferentially oriented along the (6¯11) plane. Analysis of the surface morphology reveals that the films had an average roughness increasing from 2.81 to 8.23nm as the substrate temperature increases from 30 to 200°C. The variations of the microstructural parameters, such as crystallite size (D), dislocation density (δ), the number of crystallites per unit area (N), the stacking fault probability (P) and strain (ε) with substrate temperature were investigated. Raman measurement was used to obtain more information about structural changes of Sn4Sb6S13 films. The optical parameters were deduced by using Forouhi-Bloomer models.

Synthesis and Characterization of HC(NH 2 ) 2 PbI 3 perovskite thin film prepared by single source thermal evaporation

Synthesis and Characterization of HC(NH ₂ ) ₂ PbI ₃ perovskite thin film prepared by single source thermal evaporation

Characterization of CuInS2 thin films prepared from materials grown by using the mechanochemical method and their photovoltaic applications

Cu–In–S thin films were deposited on glass substrates using single-source thermal evaporation with ternary compounds as source materials. Polycrystalline CuInS2 powder grown using the mechanochemical method was employed as the source material. After deposition, the films were annealed in H2S gas at different temperatures from 250 to 500 °C for 60 min. X-ray diffraction patterns indicated that single-phase CuInS2 was formed when annealed above 400 °C. The grain size of the crystals in thin films was approximately 0.2 to 2.0 µm. The best Al/ZnO:Al/ZnO/CdS/CuInS2/Mo solar cell had an open-circuit voltage of 360 mV, a short-circuit current density of 18.6 mA/cm2, and a fill factor of 35.5%, resulting in 2.38% efficiency.

Effects of sulfurization temperature on Cu2ZnSnS4 thin film deposited by single source thermal evaporation method

In this study, the effects of sulfurization temperature on the properties of thermally evaporated Cu2ZnSnS4 (CZTS) thin films were investigated. Molybdenum (Mo) coated soda lime glass (SLG) was used as substrates and stoichiometric CZTS powder (99.95%) was used as the source material. XRD patterns showed that CZTS were formed with preferential orientations of (112) > (220) > (312) for all the investigated films. The intensity of (112) peak is found increasing until a certain temperature indicating that the highest degree of crystallinity is achieved together with secondary phases such as ZnS and SnS. It was confirmed by raman shift at 338 cm−1 from Raman spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM) results showed a trend for surface roughness as well as morphology. From Hall effect measurement, all deposited films exhibited p-type conductivity. From UV–vis spectroscopy measurement, the optical band gap of all the films are found in the range of potential absorbers for CZTS based thin film solar cells.

Effect of intentional Na-incorporation on the structural, optical and electrical properties of CuInS2:Na thin films for solar energy conversion

Na-doped CuInS2 material is obtained by the incorporation of the sodium of an atomic percentage in amounts of 0, 0.1, 0.5, 1, 2 and 3% with a stoechiometric mixture of the elements copper, indium and sulfur taken in the stoechiometric proportions. We have investigated in this work the effect of intentional Na-incorporation on the structural, optical and electrical properties of CuInS2:Na-doped thin films grown by the single source thermal evaporation method. In the resulting Bridgman-grown ingots brittleness were increased with increased Na and measured hot point probe changed sign from p- to n-type in stoechiometric ingots above 0.5at.%. The samples having a low Na atomic percentage exhibit better crystallinity that shows the effect of the sodium for the larger percentage to degrade the crystallinity of layers (atomic percentage greater than 2at.%). The film conductivity was strongly affected by Na-doping, which increased from 10−6 to 10−3S/cm by increasing [Na]/[CuInS2] ratio from 0.1 to 3at.%. Indeed for an atomic percentage Na of 1% we obtained the biggest thickness (1μm) corresponds to the lowest refractive index value (2.08).

Growth, structural and optical properties of copper indium diselenide thin films deposited by thermal evaporation method

Copper indium diselenide (CuInSe 2) compound was synthesized by reacting its constituent’s elements copper, indium and selenium in near stoichiometric proportions (i.e. 1:1:2 with 5% excess selenium) in an evacuated quartz ampoule. Synthesized pulverized compound material was used as an evaporant material to deposit thin films of CuInSe 2 onto organically cleaned sodalime glass substrates, held at different temperatures (300–573 K), by means of single source thermal evaporation method. The phase structure and the composition of chemical constituents present in the synthesized compound and thin films have been investigated using X-ray diffraction and energy dispersive X-ray analysis, respectively. The investigations show that CuInSe 2 thin films grown above 423 K are single phase, having preferred orientation of grains along the (112) direction, and having near stoichiometric composition of elements. The surface morphology of CuInSe 2 films, deposited at different substrate temperatures, has been studied using the atomic force microscopy to estimate its surface roughness. An analysis of the transmission spectra of CuInSe 2 films, recorded in the wavelength range of 500–1500 nm, revealed that the optical absorption coefficient and the energy band gap for CuInSe 2 films, deposited at different substrate temperatures, are ∼10 4 cm −1 and 1.01–1.06 eV, respectively. The transmission spectrum was analyzed using iterative method to calculate the refractive index and the extinction coefficient of CuInSe 2 thin film deposited at 523 K. The Hall effect measurements and the temperature dependence of the electrical conductivity of CuInSe 2 thin films, deposited at different substrate temperatures, revealed that the films had electrical resistivity in the range of 0.15–20 ohm cm, and the activation energy 82–42 meV, both being influenced by the substrate temperature.

Growth and vacuum post-annealing effect on the properties of the new absorber CuSbS 2 thin films

Post-growth treatments in vacuum atmosphere were performed on CuSbS 2 films prepared by the single-source thermal evaporation method on glass substrates. The films were annealed in vacuum atmosphere for 2 h in temperature range 130–200 °C. The effect of this thermal treatment on the structural, optical and electrical properties of the films was studied. X-ray diffraction (XRD) patterns indicated that the films exhibited an amorphous structure for annealing temperature below 200 °C and a polycrystalline structure with CuSbS 2 principal phase. For the films annealed at temperatures below 200 °C one direct optical transition in range 1.8–2 eV was found. For the films annealed at 200 °C, two optical direct transitions emerged at 1.3 and 1.79 eV corresponding to the CuSbS 2 and Sb 2S 3 values respectively. The electrical measurements showed a conversion from low resistivities (3.10 − 2 –9.10 − 2 ) Ω cm for the samples annealed at temperatures below 200 °C to relatively high resistivities (2 Ω cm) for the samples annealed at 200 °C. In all cases the samples exhibited p-Ztype conductivity.

Structural, morphological and optical properties of thermal annealed TiO thin films

Structural, morphological and optical properties of TiO thin films grown by single source thermal evaporation method were studied. The films were annealed from 300 to 520 °C in air after evaporation. Qualitative film analysis was performed with X-ray diffraction, atomic force microscopy and optical transmittance and reflectance spectra. A correlation was established between the optical properties, surface roughness and growth morphology of the evaporated TiO thin films. The X-ray diffraction spectra indicated the presence of the TiO2 phase for the annealing temperature above 400 °C.

Role of oxygen in enhancing N-type conductivity of CuInS 2 thin films

Post-growth treatments in air atmosphere were performed on CuInS 2 films prepared by the single-source thermal evaporation method. Their effect on the structural, optical and electrical properties of the films was studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), optical reflection and transmission and resistance measurements. The films were annealed from 100 to 350 °C in air. The stability of the observed N-type conductivity after annealing depends strongly on the annealing temperature. Indeed it is shown that for annealing temperatures above 200 °C the N-type conductivity is stable. The resistance of the N-CuInS 2 thin films correlates well with the corresponding annealing temperature. The samples after annealing have direct bandgap energies of 1.45–1.50 eV.

Structural, electrical and optical properties of Bi‐doped CuInS 2 thin films grown by vacuum evaporation method

Structural, electrical and optical properties of Bi-doped CuInS2 thin films prepared by a single-source thermal evaporation method were investigated. The as-deposited films were annealed in the temperature range between 100 and 500 °C for 10 min in air. The film of chalcopyrite CuInS2 single phase was obtained by annealing at 200 °C successfully. It was found that Bi atoms enhanced the growth of CuInS2 single phase at lower temperature. Furthermore, the crystalline quality of doped films was higher compared with the non-doped ones. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)