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Impedance Spectroscopy: A Versatile Technique to Understand Solution-Processed Optoelectronic Devices
摘要： Solution-processed optoelectronic devices based on conjugated polymers, colloidal quantum dots (CQDs), halide perovskites, and so on are now emerging as a new-generation semiconductor technology which prevails its conventional counterparts in terms of low fabrication cost, ease of scalable manufacturing, and abundant material designability. However, the solution-processed thin films obtained through spin-coating, spray, inkjet printing, and doctor blading usually suffer from low film quality and a high defect density especially at the interfaces of different functional layers. Currently, the most significant subject is to address the non-ideal interfaces for achieving improved performance of the devices. Impedance spectroscopy (IS) is a universal technique that can help to examine the charge behavior at the interfaces in an electrochemical or solid-state multilayered device. Owing to its ability to elucidate the charge transfer, charge transport, and accumulation within the interfaces of electrochemical or multilayered devices with minimal effects to the devices themselves, the use of IS has increased vividly in the last decades. This review provides the basic principles of IS and its applications on solution-processed optoelectronic devices.
关键词： optoelectronic devices,metal halide perovskites,quantum dots,impedance spectroscopy,solution processing
更新于2025-09-23 15:22:29
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<i>(Invited)</i> Fabrication Technique for Low-Temperature Aqueous Solution-Processed Oxide Thin-Film Transistors
摘要： Solution-processing of oxide semiconductor is a promising technique for the simple and low-cost fabrication of oxide thin-film transistors (TFTs). We demonstrate improved TFT characteristics by application of a hydrogen injection and oxidation (HIO) process to the fabrication of high-performance low-temperature oxide TFTs. The compatibility of this technique for flexible substrates was also confirmed when the HIO method was applied to solution-processed metal oxide TFTs.
关键词： solution-processing,flexible substrates,low-temperature fabrication,oxide thin-film transistors,hydrogen injection and oxidation
更新于2025-09-23 15:21:21
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Hybrid Ligand Exchange of Cu(In,Ga)S <sub/>2</sub> Nanoparticles for Carbon Impurity Removal in Solution Processed Photovoltaics
摘要： The solution processing of Cu(In,Ga)(S,Se)2 photovoltaics from colloidal nanoparticles has long suffered from deleterious carbonaceous residues originating from long chain native ligands. This impurity carbon has been observed to hinder grain formation during selenization and leave a discrete residue layer between the absorber layer and the back contact. In this work, organic and inorganic ligand exchanges were investigated to remove tightly bound native oleylamine ligands from Cu(In,Ga)S2 nanoparticles, thereby removing the source of carbon contamination. However, incomplete ligand removal, poor colloidal stability, and/or selective metal etching was observed for these methods. As such, an exhaustive hybrid organic/inorganic ligand exchange was developed to bypass the limitations of individual methods. A combination of microwave-assisted solvothermal pyridine ligand stripping followed by inorganic capping with diammonium sulfide was developed and yielded greater than 98% removal of native ligands via a rapid process. Despite the aggressive ligand removal, the nanoparticle stoichiometry remained largely unaffected when making use of the hybrid ligand exchange. Furthermore, highly stable colloidal ink formulations using non-toxic dimethyl sulfoxide were developed, supporting stable nanoparticle mass concentrations exceeding 200 mg/mL. Scalable blade coating of the ligand exchanged nanoparticle inks yielded remarkably smooth and microcrack free films with RMS roughness less than 7 nm. Selenization of ligand exchanged nanoparticle films afforded substantially improved grain growth as compared to conventional non-ligand exchanged methods yielding an absolute improvement in device efficiency of 2.8%. Hybrid ligand exchange nanoparticle based devices reached total-area power conversion efficiencies of 12.0%, demonstrating the feasibility and promise of ligand exchanged colloidal nanoparticles for the solution processing of Cu(In,Ga)(S,Se)2 photovoltaics.
关键词： hybrid ligand exchange,blade coating,diammonium sulfide,carbon impurity removal,photovoltaics,grain growth,Cu(In,Ga)(S,Se)2,solution processing,ligand exchange,selenization,microwave-assisted solvothermal,colloidal nanoparticles,device efficiency
更新于2025-09-23 15:21:01
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Si-doping effect on solution-processed In-O thin-film transistors
摘要： In this work, silicon-doped indium oxide thin-film transistors (TFTs) have been fabricated for the first time by a solution processing method. By varying the Si concentration in the In2O3-SiO2 binary oxide structure up to 15 at.%, the thicknesses, densities, and crystallinity of the resulting In-Si-O (ISO) thin films were investigated by X-ray reflectivity (XRR) and X-ray diffraction techniques, while the produced TFTs were characterized by a conventional three-probe method. The results of XRR analysis revealed that the increase in the content of Si dopant increased the thickness of the produced film and reduced its density, and that all the Si-doped ISO thin films contained only a single amorphous phase even after annealing at temperatures as high as 800 °C. The manufactured ISO TFTs exhibited a reduction in the absolute value of threshold voltage VT close to 0 V and low current in the off-state, as compared to those of the non-doped indium oxide films, due to the reduced number of oxygen defects, which was consistent with the behavior of ISO TFTs fabricated by a sputtering method. The ISO TFT with a Si content of 3 at.% annealed at 400 °C demonstrated the smallest subthreshold swing of 0.5 V/dec, VT of ?5 V, mobility of 0.21 cm2/Vs, and on/off current ratio of about 2×107.
关键词： silicon-doped indium oxide,solution processing,amorphous oxide semiconductor,thin-film transistor,spin coating
更新于2025-09-23 15:21:01
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High‐Performance Solution‐Processable Flexible SnSe Nanosheet Films for Lower Grade Waste Heat Recovery
摘要： Lower grade waste heat recovery near room temperature is limited due to multiple technology challenges including low efficiency, high cost, and scalability. Here, a low-cost and scalable solution process is reported to fabricate a nanostructured SnSe thin film, and a high thermoelectric performance near room temperature is demonstrated. This transport study reveals strong phonon scattering near the interfaces between SnSe nanosheets that introduces a large thermal boundary resistance and an ultralow thermal conductivity of 0.09 W m?1 K?1. Moreover, it is demonstrated that the SnSe thin film can be readily implemented on flexible plastic substrates and preserve the high thermoelectric performance over 1000 bending cycles. Together, this study demonstrates a low-cost and scalable approach to achieve high-performance flexible thin film energy harvesting devices to power electronics and sensors near room temperature.
关键词： energy efficiency,2D van der Waals materials,solution-processing,thermoelectrics,thermal energy harvesting,phonons,nanostructures,flexible electronics
更新于2025-09-19 17:15:36
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Laser induced ultrafast combustion synthesis of solution-based AlO <sub/>x</sub> for thin film transistors
摘要： Solution processing of amorphous metal oxides using excimer laser annealing (ELA) has been lately used as a viable option to implement large-area electronics, offering high quality materials at a reduced associated cost and process time. However, the research has been focused on semiconductor and transparent conductive oxide layers rather than on the insulator layer. In this work we present amorphous aluminum oxide (AlOx) thin films produced at low temperature (≤150 °C) via combustion synthesis triggered by ELA, for oxide thin film transistors (TFTs) suitable for manufacturing flexible electronics. The study showed that combining ELA and combustion synthesis leads to an improvement in the dielectric thin film’s densification in a shorter time (≤15 min). Optimized dielectric layers were obtained combining a short drying cycle at 150 °C followed by ELA treatment. High breakdown voltage (4 MV cm?1) and optimal dielectric constant (9) was attained. In general, TFT devices comprising the AlOx fabricated with a drying cycle of 15 min followed by ELA presented great TFT properties, a high saturation mobility (20.4 ± 0.9 cm2 V?1 s?1), a small subthreshold slope (0.10 ± 0.01 V dec?1) and a turn-on voltage ≈0 V. ELA is shown to provide excellent quality solution-based high-k AlOx dielectric, that surpass other methods, like hot plate annealing and deep ultraviolet (DUV) curing. The results achieved are promising and expected to be of high value to the printed electronic industry due to the ultra-fast film densification and the surface/area selective nature of ELA.
关键词： thin film transistors,excimer laser annealing,solution processing,amorphous metal oxides,combustion synthesis,flexible electronics
更新于2025-09-19 17:13:59
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Keratin Film as Natural and Eco‐Friendly Support for Organic Optoelectronic Devices
摘要： This work describes the preparation of a novel substrate based on keratin extracted from wool and its application as potential support for solution-processed organic solar cells. Optically transparent, free-standing, and resistant keratin films are successfully prepared, starting from water solution, and characterized in terms of morphology, structure, thermal and mechanical properties. The effect of solvents and thermal annealing is also investigated in order to mimic and evaluate the impact of the processing conditions used for devices fabrication. Thermally annealed keratin films exhibit enhanced optical transparency (>87%) in the visible region of the spectrum, a transition from α-helix to β-sheet and turn structures, improved thermal stability and Young’s modulus. The good transparency, flatness, and resistance of as-cast substrates allow the successful preparation of organic solar cells. Photovoltaic performances similar to those reported for other natural/biobased supports are achieved, confirming the potential of keratin film as an alternative and promising support material for eco-friendly, fully printable, sustainable, and inexpensive optoelectronic devices.
关键词： natural support,optoelectronic devices,eco-friendly systems,keratin film,solution processing
更新于2025-09-19 17:13:59
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In Situ Light-Initiated Ligands Crosslinking Enables Efficient All-Solution-Processed Perovskite Light-Emitting Diodes
摘要： Solution process has been considered to be an effective method to fabricate emitting layer (EML) in light-emitting diodes (LEDs). However, the fabrication of charge transport layer (CTL) above the perovskite EML by solution processing is challenging. Herein, we incorporated polymerizable molecules, conjugated linoleic acid (CLA), as surface ligands to passivate perovskite QDs. The polymerized CLA can create a crosslinked QD film, which allows the solution deposition of subsequent CTLs. The theoretical calculations reveal that the binding energy of polymerized CLA with QDs increased, and the strong ligands binding state can better passivate the surface and improve the stability of QDs. As a result, all-solution-processed multilayer perovskite LEDs were fabricated with performance of a max luminance of 2470 cd/m2 for CsPbBr3-based devices, and a peak EQE of 2.67% for CsPbI3-based devices. These results demonstrate that the in situ light-initiated ligands crosslinking can be an effective strategy in all-solution-processed optoelectronic devices.
关键词： optoelectronic devices,light-emitting diodes,solution processing,perovskite quantum dots,ligands crosslinking
更新于2025-09-16 10:30:52
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Starburst-type triarylphosphine oxide trimers forming a stable amorphous n-type layer in solution-processed multilayer OLED
摘要： Novel starburst-type triphenylphosphine oxide trimers PO-1 and PO-2 were synthesized aimed at application as an electron-transporting material for multilayer organic light-emitting diodes (OLEDs). They showed high glass transition temperatures (Tg; 175 and 205 (cid:1)C, respectively) and high lowest triplet energies (T1; 2.81 and 2.78 eV, respectively). Their high solubility in 2-propanol allowed us to fabricate multilayer OLEDs by solution processing, and a double-emitting layer OLED consisting of poly(9-vinylcarbazole)-based p-type and PO-1-based n-type layers doped with a phosphorescent material (FIrpic) showed efficient sky-blue electroluminescence with a maximum external quantum efficiency of 9.33%.
关键词： Solution processing,Organic light-emitting diode,Phosphine oxide,Double emitting layer,Multilayer,Electron-transporting material
更新于2025-09-16 10:30:52
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Efficient and Stable PbS Quantum Dot Solar Cells by Triple-Cation Perovskite Passivation
摘要： Solution-processed quantum dots (QDs) have a high potential for fabricating low cost, flexible and large-scale solar energy harvesting devices. It has recently been demonstrated that hybrid devices employing a single monovalent cation perovskite solution for PbS QD surface passivation exhibit enhanced photovoltaic performance when compared to standard ligand passivation. Herein we demonstrate that the use of a triple cation Cs0.05(MA0.17FA0.83)0.95Pb(I0.9Br0.1)3 perovskite composition for surface passivation of the quantum dots results in highly efficient solar cells, which maintain 96 % of their initial performance after 1200h shelf storage. We confirm perovskite shell formation around the PbS nanocrystals by a range of spectroscopic techniques as well as high-resolution transmission electron microscopy. We find that the triple cation shell results in a favorable energetic alignment to the core of the dot, resulting in reduced recombination due to charge confinement without limiting transport in the active layer. Consequently, photovoltaic devices fabricated via a single-step film deposition reached a maximum AM1.5G power conversion efficiency of 11.3 % surpassing most previous reports of PbS solar cells employing perovskite passivation.
关键词： quantum dots,solution-processing,triple cation,solar cells,hybrid perovskite
更新于2025-09-12 10:27:22