Inorganic Films Research Articles

Reaction mechanisms of α,ω-bifunctional molecules toward atomic layer deposition versus molecular layer deposition

Atomic layer deposition (ALD) and molecular layer deposition (MLD) are key techniques used to fabricate high-quality thin films. Organic α,ω-bifunctional precursors often exhibit different growth behaviors depending on the functional groups as well as the chain length of the molecular backbone, so that some organic precursors produce thin films of organic-inorganic hybrid materials, while others may deposit purely inorganic thin films without incorporation of the hydrocarbon moiety. In this study, we investigated the surface reaction mechanisms of α,ω-bifunctional molecules (X(CH2)nX, n = 2, 3, 4, 5, 6, and X = OH, SH, NH2) with diethylzinc toward MLD and ALD using density functional theory (DFT) calculations. It was found that the length of the aliphatic alkyl chain and the terminal functional groups of bifunctional organic precursors significantly influences their reactivity, resulting in the possibility toward removal or incorporation of the organic moiety in the product. Bifunctional reactants with longer alkyl backbones (n > 4) showed higher reactivity for removal of the hydrocarbon chain, facilitated by a ω-2 hydrogen transfer reaction. Furthermore, a reactivity trend of SH > OH > NH2 for removal of the hydrocarbon chains was observed. Our study provides in-depth theoretical insights into the adsorption reaction mechanisms occurring when bifunctional molecules are employed as organic reactants in ALD and MLD processes.

In situ temperature synthesis and characterization of ferroelectric PZN-4.5PT nanoparticles’ thin films using synchrotron light source

ABSTRACT Despite the excellent properties of Pb(Zn1/3Nb2/3)O3-4.5PbTiO3 (PZN-4.5PT) single crystals, the greatest difficulty for their application on electronic devices is to make them to thin layers related to the difficulty to make them as ceramic materials. In this paper, we use the combined USAXS/SAXS/WAXS instrument at 9ID beamline at APS-ANL for in situ characterization of PZN-4.5PT inorganic perovskite nanoparticles thin films deposited on nanotextured silicon to understand the phase transitions and determine the observed microcrystals' structure. The sample was annealed from ambient to 1000°C. The results revealed structure changes in the nanoparticles' thin films which could be explained by the new phase that can be assigned to the Pb3(PO4)2-based component. The peak at 31° indicates the presence of the rhombohedral phase perovskites assigned to the nanoparticles. WAXS characterization permitted to identification of many transitions during thermal annealing like dehydration or dihydroxylation of phosphorus gel –OH bonds and internal water.

Photocurrent Enhancement by Copper Incorporation in Chemical-Solution-Synthesized Inorganic Lead Perovskite Thin Films.

Perovskite thin films are at the forefront of highly promising photovoltaic technologies due to their remarkable optoelectronic properties. Herein, we explore a low-cost, reproducible, and industry-scalable methodology to synthesize an all-inorganic CsPbI1.5Br1.5 perovskite thin film with additional incorporation of copper and chloride ions into the lattice structure. The synthesis process involves chemical bath deposition of PbS, followed by a gas-solid iodination reaction to yield PbI2. Subsequently, dip-coating incorporates Cs+, Cu2+, Br-, and Cl- ions into PbI2, and annealing at 270 °C produces perovskite thin films. The results show a large coverage area and a uniform thickness of each perovskite thin film. Comprehensive characterization, including X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and photoluminescence, provides the structural, chemical, and optical properties of the synthesized thin films. To evaluate the practical implications of our methodology, we fabricated photodetectors employing CsPbI1.5Br1.5 and (Cs0.95:Cu0.01)PbI1.5Br1.3Cl0.1 perovskite films. A comparative analysis unequivocally demonstrates a significant increase in photodetector performance when utilizing (Cs0.95:Cu0.01)PbI1.5Br1.3Cl0.1 perovskite films. While our findings quantitatively assess the tangible enhancement in photocurrent, we acknowledge the potential for improvement in device fabrication to enhance the overall performance. This study not only affirms the successful low-cost synthesis of perovskite thin films but also emphasizes the pivotal role of Cu2+ and Cl- ions in enhancing the performance of perovskite-based optoelectronic devices.

Inorganic Multilayer Film with High Infrared Selective Emission Enhanced by SiNx for Daytime Radiative Cooling

Inorganic Multilayer Film with High Infrared Selective Emission Enhanced by SiN_<i>x</i> for Daytime Radiative Cooling

Ultrahigh thermoelectric properties of p‐type BixSb2−xTe3 thin films with exceptional flexibility for wearable energy harvesting

AbstractUse of a flexible thermoelectric source is a feasible approach to realizing self‐powered wearable electronics and the Internet of Things. Inorganic thin films are promising candidates for fabricating flexible power supply, but obtaining high‐thermoelectric‐performance thin films remains a big challenge. In the present work, a p‐type BixSb2−xTe3 thin film is designed with a high figure of merit of 1.11 at 393 K and exceptional flexibility (less than 5% increase in resistance after 1000 cycles of bending at a radius of ∼5 mm). The favorable comprehensive performance of the BixSb2−xTe3 flexible thin film is due to its excellent crystallinity, optimized carrier concentration, and low elastic modulus, which have been verified by experiments and theoretical calculations. Further, a flexible device is fabricated using the prepared p‐type BixSb2−xTe3 and n‐type Ag2Se thin films. Consequently, an outstanding power density of ∼1028 μW cm−2 is achieved at a temperature difference of 25 K. This work extends a novel concept to the fabrication of high‐performance flexible thin films and devices for wearable energy harvesting.

High stability visible-light photoresponse of flexible heterostructures based on LaCoO3 epitaxial films

The research of high-speed photodetector and high-speed optical receiver garners significant attention due to their indispensable properties in many fields including high-temperature event monitoring, security, and ad hoc network wireless communication. Inorganic perovskite oxides LaCoO3 films showcase an extensive prospect in this area owing to their remarkable photoconductive effect. Up to present, however, LaCoO3 films are mostly grown on rigid instead of flexible substrates, greatly limiting their applications to wearable optoelectronic sensors. In this work, we fabricated some flexible LaCoO3 thin films to study their photoresponse. By inserting SrTiO3 and BaTiO3 as buffer layers, we find that LaCoO3 thin films could epitaxially grow on the fluorphlogopite surface and show a stable photoresponse to visible-light. Nevertheless, we also found that the epitaxial strain and the content of surface-adsorbed oxygen could impact the photoconductivity. The mechanical strain generated by bending the fluorphlogopite substrate has been confirmed to has a tunable effect on the photoresponse. Moreover, with the fatigue tests of 105 bending cycles, the flexible LaCoO3 thin films maintain a good photoresponse without any essentially weakening, proving a superior mechanical durability and stability. This work not only indicates the feasibility of the LaCoO3 films applied for flexible photodetectors but also opens a path for other perovskite films applications for flexible substrate.

Enhancing grain growth of caesium-formamidinium-based lead halide perovskite thin films through PbI2 precursor engineering in vapor-solid reaction

Vapor-solid reaction methods are highly regarded as potential solutions for large-scale production of perovskite thin films due to their scalability, compatibility with silicon tandem technology, and lack of solvents. However, the limited penetration of organic vapor through the solid inorganic film results in a slow growth rate of perovskite, leading to poor crystallinity and small grain size. This high defect density in the grain boundaries hinders the enhancement of device performance. In this study, we used 1,3-diaminoguanidine monohydrochloride as an additive in the PbI2 precursor films, which effectively improved perovskite grain growth in the vapor-solid reaction process. After optimization, we achieved high-quality perovskite thin films with a large grain size exceeding 5 μm. Notably, solar devices based on these large-grain perovskite thin films achieved a high power conversion efficiency up to 21.13%.

Effective surface passivation for stable and high-performance inverted CsPbI2Br perovskite solar cells with efficiency over 15%

Inverted CsPbI2Br perovskite solar cells (PSCs) still suffer from substantially non-radiative recombination losses at the perovskite interface, which limits the future advancement of CsPbI2Br perovskite-based single- and multi-junction photovoltaic cells. Interfacial defect passivation of perovskite films is an effective approach for enhancing the performance of PSCs. In this study, we introduce thiophene halide salts with different side groups on the surface of CsPbI2Br films to passivate the inorganic perovskite film and investigate their passivation effects. Our studies show that the 2-thiophenemethylammonium iodide (TM) passivator with –CH2NH3I side group effectively mitigates the trap density of the perovskite film by forming coordination bonding with Pb2+ ions, thus significantly inhibiting the non-radiative recombination in the resulting PSC. In addition, after the TM treatment, the better energy-level alignment between the CsPbI2Br/[6,6]-Phenyl C61 butyric acid methyl ester (PCBM) interface is achieved, thus enhancing the charge extraction from perovskite to the charge transport layer. The resulting inverted CsPbI2Br device demonstrates a significantly enhanced champion efficiency of 15.07% with a Voc of 1.16 V, Jsc of 16.42 mA/cm2, and FF of 79.11%, compared to the 11.19% efficiency of the control device, and maintains >97% of the initial efficiency after being stored for over 1700 h in N2 atmosphere. This work confirms the importance of substituent groups on surface passivation molecules for effective passivation of defects and optimization of energy levels, particularly for Voc improvement.

Ultrathin, Transferred Layers of Silicon Oxynitrides as Tunable Biofluid Barriers for Bioresorbable Electronic Systems.

Bio/ecoresorbable electronic systems create unique opportunities in implantable medical devices that serve a need over a finite time period and then disappear naturally to eliminate the need for extraction surgeries. A critical challenge in the development of this type of technology is in materials that can serve as thin, stable barriers to surrounding ground water or biofluids, yet ultimately dissolve completely to benign end products. This paper describes a class of inorganic material (silicon oxynitride, SiON) that can be formed in thin films by plasma-enhanced chemical vapor deposition for this purpose. In vitro studies suggest that SiON and its dissolution products are biocompatible, indicating the potential for its use in implantable devices. A facile process to fabricate flexible, wafer-scale multilayer films bypasses limitations associated with the mechanical fragility of inorganic thin films. Systematic computational, analytical, and experimental studies highlight the essential materials aspects. Demonstrations in wireless light-emitting diodes both in vitro and in vivo illustrate the practical use of these materials strategies. The ability to select degradation rates and water permeability through fine tuning of chemical compositions and thicknesses provides the opportunity to obtain a range of functional lifetimes to meet different application requirements.

Thermal engineering control of inorganic perovskite CsPbIBr2 film and optimization of photoelectric performance

Thermal engineering control of inorganic perovskite CsPbIBr2 film and optimization of photoelectric performance

Technology for obtaining VO2 films from the gas phase during thermal decomposition

The paper considers the process of obtaining films of vanadium dioxide by the method of deposition of inorganic coatings and films from the vapor phase during the thermal decomposition of organometallic compounds. In recent years, there has been a growing interest in the practical use of organometallic compounds. This has led to the development of many devices that include various vapor deposition techniques. This technology is currently being used as the latest technology. The design of the technological installation for pyrometric film deposition is presented and the principle of operation is given. In the course of the study, film samples were obtained and experimental work was carried out. The results obtained are presented in the form of graphs.

Pulse irradiation synthesis of metal chalcogenides on flexible substrates for enhanced photothermoelectric performance

High synthesis temperatures and specific growth substrates are typically required to obtain crystalline or oriented inorganic functional thin films, posing a significant challenge for their utilization in large-scale, low-cost (opto-)electronic applications on conventional flexible substrates. Here, we explore a pulse irradiation synthesis (PIS) to prepare thermoelectric metal chalcogenide (e.g., Bi2Se3, SnSe2, and Bi2Te3) films on multiple polymeric substrates. The self-propagating combustion process enables PIS to achieve a synthesis temperature as low as 150 °C, with an ultrafast reaction completed within one second. Beyond the photothermoelectric (PTE) property, the thermal coupling between polymeric substrates and bismuth selenide films is also examined to enhance the PTE performance, resulting in a responsivity of 71.9 V/W and a response time of less than 50 ms at 1550 nm, surpassing most of its counterparts. This PIS platform offers a promising route for realizing flexible PTE or thermoelectric devices in an energy-, time-, and cost-efficient manner.

Ultrastable and high-performance amplified spontaneous emission in centimeter-scale inorganic CsPbBr3 single-crystal thin films

In this work, high-quality and centimeter-scale CsPbBr3 perovskite single-crystal thin films were grown using the metal-organic chemical vapor deposition method. Extremely flat surfaces without distinct grain boundaries were observed throughout the thin films. A high polarized degree of approximately 0.52 was measured from the single-crystal thin films by analyzing the polarization of the photoluminescence emission spectra. Low threshold amplified spontaneous emissions with an optical gain coefficient of 1215 cm−1 under the excitation energy of 301 μJ/cm2 and the highest value of 2857 cm−1 under the excitation energy of 1.08 mJ/cm2 were investigated under the excitation of a nanosecond laser at 266 nm. The CsPbBr3 single-crystal thin films showed excellent stability where the optical gain coefficient could be maintained over 1800 cm−1 after exposure to air for ten months. The results of this study not only provide high-quality single-crystal films for laser applications but also put forward a feasible scheme to improve the stability of the materials.

Intense pulsed light annealing of solution-based indium–gallium–zinc–oxide semiconductors with printed Ag source and drain electrodes for bottom gate thin film transistors

In this study, an intense pulsed light (IPL) annealing process for a printed multi-layered indium–gallium–zinc–oxide (IGZO) and silver (Ag) electrode structure was developed for a high performance all-printed inorganic thin film transistor (TFT). Through a solution process using IGZO precursor and Ag ink, the bottom gate structure TFT was fabricated. The spin coating method was used to form the IGZO semiconductor layer on a heavily-doped silicon wafer covered with thermally grown silicon dioxide. The annealing process of the IGZO layer utilized an optimized IPL irradiation process. The Ag inks were printed on the IGZO layer by screen printing to form the source and drain (S/D) pattern. This S/D pattern was dried by near infrared radiation (NIR) and the dried S/D pattern was sintered with intense pulsed light by varying the irradiation energy. The performances of the all-printed TFT such as the field effect mobility and on–off ratio electrical transfer properties were measured by a parameter analyzer. The interfacial analysis including the contact resistance and cross-sectional microstructure analysis is essential because diffusion phenomenon can occur during the annealing and sintering process. Consequently, this TFT device showed noteworthy performance (field effect mobility: 7.96 cm2/V s, on/off ratio: 107). This is similar performance compared to a conventional TFT, which is expected to open a new path in the printed metal oxide-based TFT field.

Manual shaking exfoliation of large‐size two‐dimensional LiInP2S6 nanosheets with exponential change in ionic conductivity for water detection

AbstractLarge‐sized and atomically thin two‐dimensional metal thiophosphate materials have been widely exploited in detectors due to their rich physical/chemical properties of high surface area and massive adjustable sites. However, existing production methods are limited in terms of meeting the demanding challenges in achieving the scalable fabrication of high‐quality nanomaterials under mild conditions. Here, we develop a facile intercalation–exfoliation method that can fabricate large lateral size (&gt;23 μm) and few‐layer LiInP2S6 nanosheets with high crystalline quality fast. Due to the advantage of hydrophilicity of lithium, swelled interlayer spacing can be obtained, which enables the rapid exfoliation by only slight manual shaking within tens of seconds. Concomitantly, the inorganic LiInP2S6 film manufactured by nanosheets has inter‐connected ionic channels, which can be adjusted on the basis of the water content, enabling tunable ionic conductivity. As a result, ionic conductor films using ions as charge carriers can achieve high water response with good repeatability and excellent long‐term stability in a wide moisture range. Moreover, the as‐prepared detector has excellent capability in real‐time noncontact human–machine interfacing. This study, not only is a powerful strategy for the fabrication of large‐sized and high‐quality nanosheets presented but also proof for the promising development of iontronic devices in new applications.

A facile in-situ reaction method for preparing flexible Sb2Te3 thermoelectric thin films

Inorganic p-type Sb2Te3 flexible thin films (f-TFs) with eco-friendly and high thermoelectric performance have attracted wide research interest and potential for commercial applications. This study employs a facile in-situ reaction method to prepare flexible Sb2Te3 thin films by rationally adjusting the synthesized temperature. The prepared thin films show good crystallinity, which enhances the electrical conductivity of ~1,440 S·cm-1 due to the weakened carrier scattering. Simultaneously, the optimized carrier concentration, through adjusting the synthesis temperature, causes the intermediate Seebeck coefficient. Consequently, a high-power factor (16.0 μW·cm-1·K-2 at 300 K) is achieved for Sb2Te3 f-TFs prepared at 623 K. Besides, the f-TFs also exhibit good flexibility due to the slight change in resistance after bending. This study specifies that the in-situ reaction method is an effective route to prepare Sb2Te3 f-TFs with high thermoelectric performance.

Recent Advances and Prospects of Solution‐Processed Efficient Sb2S3 Solar Cells

AbstractSolar cells comprising earth‐abundant and non‐toxic elements with applicable bandgaps and high absorption coefficients have attracted considerable interest over the past several decades and are important devices for addressing the future demand for clean and renewable energy. Antimony sulfide (Sb2S3) crystal material effectively meets these requirements owing to its suitable bandgap, high absorption coefficient, high electron and hole mobilities, earth abundance, and excellent stability. Solution‐processed Sb2S3 films are essential to facilitate the fabrication of low‐cost, large‐scale, and high‐efficiency photovoltaic devices, but suffer from several shortcomings of large intrinsic defects, high interfacial barrier, and atomic mismatch, uncontrollable film thickness, and crystal orientation. In this review, a systematic overview of the fundamental properties of solution‐processed Sb2S3 materials is presented, and then interface engineering, defect passivation and control strategies, crystal orientation and modulation methods, device structure, and the performance of Sb2S3 solar cells are focused, highlighting the primary advancements and major challenges based on this technology. Finally, several creative perspectives and constructive innovation strategies for future research on Sb2S3 photovoltaic devices are provided, indicating a roadmap for the practical application of other inorganic semiconductor heterojunction thin film solar cells.

A layering technique for achieving pinhole-free organic–inorganic halide perovskite thin films through the vapor–solid reaction

A multi-stage vapor–solid reaction technique was introduced to form segmented perovskite thin films. The triple-layer film exhibited a dense, pinhole-free structure. Solar cells made from it achieved a champion power conversion efficiency of 21.09%.

Chemical nanoimaging of octylphosphonic acid molecular additives on hybrid organic–inorganic perovskite films

By employing AFM-IR, this work uncovered the passivation mechanism of the OPA additive on perovskite films.

Molecular design direction of organic spacer cations for low-dimensional organic–inorganic hybrid perovskite thin film transistors

Organic spacer cations in low-dimensional organic–inorganic hybrid perovskites (LDPVKs) significantly affect the performance of perovskite materials and devices. Herein, we systematically examine the effects of four distinct organic spacer cations on the properties of materials and perovskite thin film transistors (TFTs). Our study explores the consequences of varying chain lengths, including butylamine (BA) and octylamine (OA), and also considers the impact of incorporating benzene rings, such as phenethylamine (PEA), as well as the influence of fluorine-substituted benzene ring side chains, as represented by fluorine-substituted phenethylamine (FPEA), within these organic spacer cations. The results show that long-chain organic cations such as alkyl-chain cations improve the stability of TFTs but does not improve its field effect mobility. Because it provides π-π stacking, the benzene ring cation improves the carrier mobility performance of LDPVKs. This significantly improves the electrical performance and stability of LDPVK TFTs, affording a field-effect mobility of 7.47 cm2/(V·s) and the threshold voltage difference between the positive and negative sweep (ΔVTH) of 0.25 V. Therefore, when designing provide a molecular design direction for selecting organic spacer cations in low-dimensional for organic–inorganic hybrid perovskites, various factors should be considered to optimized. This work study guides the designing LDPVKs and improving the performances of field-effect devices in the future.