Search Results (15)

Titanium dioxide (TiO₂) is a wide-bandgap semiconductor material with broad application potential, known for its excellent photocatalytic performance, high chemical stability, low cost, and non-toxicity. These properties make it highly attractive for applications in photovoltaic energy, environmental remediation, and optoelectronic devices. For instance, TiO₂ is widely used as a photocatalyst for hydrogen production via water splitting and for degrading organic pollutants, thanks to its efficient photo-generated electron–hole separation. Additionally, TiO₂ exhibits remarkable performance in dye-sensitized solar cells and photodetectors, providing critical support for advancements in green energy and photoelectric conversion technologies. Boron-doped diamond (BDD) is renowned for its exceptional electrical conductivity, high hardness, wide electrochemical window, and outstanding chemical inertness. These unique characteristics enable its extensive use in fields such as electrochemical analysis, electrocatalysis, sensors, and biomedicine. For example, BDD electrodes exhibit high sensitivity and stability in detecting trace chemicals and pollutants, while also demonstrating excellent performance in electrocatalytic water splitting and industrial wastewater treatment. Its chemical stability and biocompatibility make it an ideal material for biosensors and implantable devices. Research indicates that the combination of TiO₂ nanostructures and BDD into heterostructures can exhibit unexpected optical and electrical performance and transport behavior, opening up new possibilities for photoluminescence and rectifier diode devices. However, applications based on this heterostructure still face challenges, particularly in terms of photodetector, photoelectric emitter, optical modulator, and optical fiber devices under high-temperature conditions. This article explores the potential and prospects of their combined heterostructures in the field of optoelectronic devices such as photodetector, light emitting diode (LED), memory, field effect transistor (FET) and sensing. TiO₂/BDD heterojunction can enhance photoresponsivity and extend the spectral detection range which enables stability in high-temperature and harsh environments due to BDD’s thermal conductivity. This article proposes future research directions and prospects to facilitate the development of TiO₂ nanostructured materials and BDD-based heterostructures, providing a foundation for enhancing photoresponsivity and extending the spectral detection range enables stability in high-temperature and high-frequency optoelectronic devices field. Further research and exploration of optoelectronic devices based on TiO₂-BDD heterostructures hold significant importance, offering new breakthroughs and innovations for the future development of optoelectronic technology. Full article

The complex of hypofluorous acid with acetonitrile—HOF•CH₃CN—is the only substance possessing a truly electrophilic oxygen. This fact makes it the only tool suitable for transferring oxygen atoms to sites that are not accessible to this vital element. We will review here most of the known organic reactions with this complex, which is easily made by bubbling dilute fluorine through aqueous acetonitrile. The reactions of HOF•CH₃CN with double bonds produce epoxides in a matter of minutes at room temperature, even when the olefin is electron-depleted and cannot be epoxidized by any other means. The electrophilic oxygen can also substitute deactivated tertiary C-H bonds via electrophilic substitution, proceeding with full retention of configuration. Using this complex enables transferring oxygen atoms to a carbonyl and oxidizing alcohols and ethers to ketones. The latter could be oxidized to esters via the Baeyer–Villiger reaction, proving once again the validity of the original Baeyer mechanism. Azines are usually avoided as protecting groups for carbonyl since their removal is problematic. HOF•CH₃CN solves this problem, as it is very effective in recreating carbonyls from the respective azines. A bonus of the last reaction is the ability to replace the common ¹⁶O isotope of the carbonyl with the heavier ¹⁷O or ¹⁸O in the simplest and cheapest possible way. The reagent can transfer oxygen to most nitrogen-containing molecules. Thus, it turns practically any azide or amine into nitro compounds, including amino acids. This helps to produce novel α-alkylamino acids. It also attaches oxygen atoms to most tertiary nitrogen atoms, including certain aromatic ones, which could not be obtained before. HOF•CH₃CN was also used to make five-member cyclic poly-NO derivatives, many of them intended to be highly energetic materials. The nucleophilic sulfur atom also reacts very smoothly with the reagent in a wide range of compounds to form sulfone derivatives. While common sulfides are easily converted to sulfones by many orthodox reagents, electron-depleted ones, such as R_f-S-Ar, can be oxidized to R_f-SO₂-Ar only with this reagent. The mild reaction conditions also make it possible to synthesize a whole range of novel episulfones and offer, as a bonus, a very easy way to make S^xO₂, x being any isotope variation of oxygen. These mild conditions also helped to oxidize thiophene to thiophen-S,S-dioxide without the Diels–Alder dimerizations, which usually follow such dioxide formation. The latter reaction was a prelude to a series of preparations of [all]-S,S-dioxo-oligothiophenes, which are important for the efficient preparation of active layers in field-effect transistors (FETs), as such oligomers are considered to be important for organic semiconductors for light-emitting diodes (LEDs). Several types of these oligothiophenes were prepared, including partly or fully oxygenated ones, star-oligothiophenes, and fused ones. Several [all]-S,S-dioxo-oligo-thienylenevinylenes were also successfully prepared despite the fact that they also possess carbon–carbon p centers in their molecules. All oxygenated derivatives have been prepared for the first time and have lower HOMO-LUMO gaps compared to their parent compounds. HOF•CH₃CN was also used to oxidize the surface of the nanoparticles of oligothiophenes, leaving the core of the nanoparticle unchanged. Several highly interesting features have been detected, including their ability to photostimulate the retinal neurons, especially the inner retinal ones. HOF•CH₃CN was also used on elements other than carbon, such as selenium and phosphor. Various selenides were oxidized to the respective selenodioxide derivatives (not a trivial task), while various phosphines were converted efficiently to the corresponding phosphine oxides. Full article

In this paper, a pixel circuit consists of four MOSFETs and one capacitor is proposed for Organic Light-Emitting Diode on Silicon (OLEDoS) microdisplays. The proposed pixel circuit enhances luminance uniformity by compensating for the threshold voltage variation of the driving transistors by the capacitive coupling effect. Even with a threshold voltage variation of ±20 mV, the HSPICE simulation results reveal that the driving current offset stays between −0.89 and 0.70 LSB, which is more than seven times smaller than that of the conventional 2T1C pixel circuit. Additionally, a two-stage DAC driving scheme has been utilized to achieve 256 gray levels, aiming to reduce the accuracy requirements for the DAC circuit. The proposed pixel circuit demonstrates significant potential in high-performance OLEDoS microdisplay applications. Full article

Metal oxide semiconductors, such as indium gallium zinc oxide (IGZO), have attracted significant attention from researchers in the fields of liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs) for decades. This interest is driven by their high electron mobility of over ~10 cm²/V·s and excellent transmittance of more than ~80%. Amorphous IGZO (a-IGZO) offers additional advantages, including compatibility with various processes and flexibility making it suitable for applications in flexible and wearable devices. Furthermore, IGZO-based thin-film transistors (TFTs) exhibit high uniformity and high-speed switching behavior, resulting in low power consumption due to their low leakage current. These advantages position IGZO not only as a key material in display technologies but also as a candidate for various next-generation electronic devices. This review paper provides a comprehensive overview of IGZO-based electronics, including applications in gas sensors, biosensors, and photosensors. Additionally, it emphasizes the potential of IGZO for implementing logic gates. Finally, the paper discusses IGZO-based neuromorphic devices and their promise in overcoming the limitations of the conventional von Neumann computing architecture. Full article

Macrocycles have attracted significant attention from academia due to their various applications in organic field-effect transistors, organic light-emitting diodes, organic photovoltaics, and dye-sensitized solar cells. Despite the existence of reports on the application of macrocycles in organic optoelectronic devices, these reports are mainly limited to analyzing the structure–property relationship of a particular type of macrocyclic structure, and a systematic discussion on the structure–property is still lacking. Herein, we conducted a comprehensive analysis of a series of macrocycle structures to identify the key factors that affect the structure–property relationship between macrocycles and their optoelectronic device properties, including energy level structure, structural stability, film-forming property, skeleton rigidity, inherent pore structure, spatial hindrance, exclusion of perturbing end-effects, macrocycle size-dependent effects, and fullerene-like charge transport characteristics. These macrocycles exhibit thin-film and single-crystal hole mobility up to 10 and 26.8 cm² V⁻¹ s⁻¹, respectively, as well as a unique macrocyclization-induced emission enhancement property. A clear understanding of the structure–property relationship between macrocycles and optoelectronic device performance, as well as the creation of novel macrocycle structures such as organic nanogridarenes, may pave the way for high-performance organic optoelectronic devices. Full article

In recent years, the active-matrix organic light-emitting diode (AMOLED) displays have been greatly required. A voltage compensation pixel circuit based on an amorphous indium gallium zinc oxide thin-film transistor is presented for AMOLED displays. The circuit is composed of five transistors–two capacitors (5T2C) in combination with an OLED. In the circuit, the threshold voltages of both the transistor and the OLED are extracted simultaneously in the threshold voltage extraction stage, and the mobility-related discharge voltage is generated in the data input stage. The circuit not only can compensate the electrical characteristics variation, i.e., the threshold voltage variation and mobility variation, but also can compensate the OLED degradation. Furthermore, the circuit can prevent the OLED flicker, and can achieve the wide data voltage range. The circuit simulation results show that the OLED current error rates (CERs) are lower than 3.89% when the transistor’s threshold voltage variation is ±0.5V, lower than 3.49% when the mobility variation is ±30%. Full article

This review article covers the synthesis and design of conjugated polymers for carefully adjusting energy levels and energy band gap (EBG) to achieve the desired photovoltaic performance. The formation of bonds and the delocalization of electrons over conjugated chains are both explained by the molecular orbital theory (MOT). The intrinsic characteristics that classify conjugated polymers as semiconducting materials come from the EBG of organic molecules. A quinoid mesomeric structure (D-A ↔ D⁺ = A⁻) forms across the major backbones of the polymer as a result of alternating donor–acceptor segments contributing to the pull–push driving force between neighboring units, resulting in a smaller optical EBG. Furthermore, one of the most crucial factors in achieving excellent performance of the polymer is improving the morphology of the active layer. In order to improve exciton diffusion, dissociation, and charge transport, the nanoscale morphology ensures nanometer phase separation between donor and acceptor components in the active layer. It was demonstrated that because of the exciton’s short lifetime, only small diffusion distances (10–20 nm) are needed for all photo-generated excitons to reach the interfacial region where they can separate into free charge carriers. There is a comprehensive explanation of the architecture of organic solar cells using single layer, bilayer, and bulk heterojunction (BHJ) devices. The short circuit current density (J_sc), open circuit voltage (V_oc), and fill factor (FF) all have a significant impact on the performance of organic solar cells (OSCs). Since the BHJ concept was first proposed, significant advancement and quick configuration development of these devices have been accomplished. Due to their ability to combine great optical and electronic properties with strong thermal and chemical stability, conjugated polymers are unique semiconducting materials that are used in a wide range of applications. According to the fundamental operating theories of OSCs, unlike inorganic semiconductors such as silicon solar cells, organic photovoltaic devices are unable to produce free carrier charges (holes and electrons). To overcome the Coulombic attraction and separate the excitons into free charges in the interfacial region, organic semiconductors require an additional thermodynamic driving force. From the molecular engineering of conjugated polymers, it was discovered that the most crucial obstacles to achieving the most desirable properties are the design and synthesis of conjugated polymers toward optimal p-type materials. Along with plastic solar cells (PSCs), these materials have extended to a number of different applications such as light-emitting diodes (LEDs) and field-effect transistors (FETs). Additionally, the topics of fluorene and carbazole as donor units in conjugated polymers are covered. The Stille, Suzuki, and Sonogashira coupling reactions widely used to synthesize alternating D–A copolymers are also presented. Moreover, conjugated polymers based on anthracene that can be used in solar cells are covered. Full article

This paper proposes a new 6T1C pixel circuit based on low-temperature polycrystalline oxide (LTPO) technology for portable active-matrix organic light-emitting diode (AMOLED) displays with variable refresh rates ranging from 1 to 120 Hz. The proposed circuit has a simple structure and is based on the design of sharing lines of switch-controlling signals. It also provides low-voltage driving and immunity to OLED degeneration issues. The calculation and analysis of programming time are discussed, and the optimal storage capacitor for the proposed circuit’s high-speed driving is selected. The results of the simulation reveal that threshold voltage variations in driving thin-film transistors of ±0.33 V can be well sensed and compensated with a 1.8% average shift of OLED currents in high-frame-rate operation (120 Hz), while the maximum variation in OLED currents within all gray levels is only 3.56 nA in low-frame-rate operation (1 Hz). As a result, the proposed 6T1C pixel circuit is a good candidate for use in portable AMOLED displays. Full article

Organic light emitting transistors (OLETs) combine, in the same device, the function of an electrical switch with the capability of generating light under appropriate bias conditions. In this work, we demonstrate how engineering the dielectric layer based on high-k polyvinylidene fluoride (PVDF)-based polymers can lead to a drastic reduction of device driving voltages and the improvement of its optoelectronic properties. We first investigated the morphology and the dielectric response of these polymer dielectrics in terms of polymer (P(VDF-TrFE) and P(VDF-TrFE-CFE)) and solvent content (cyclopentanone, methylethylketone). Implementing these high-k PVDF-based dielectrics enabled low-bias ambipolar organic light emitting transistors, with reduced threshold voltages (<20 V) and enhanced light output (compared to conventional polymer reference), along with an overall improvement of the device efficiency. Further, we preliminary transferred these fluorinated high-k dielectric films onto a plastic substrate to enable flexible light emitting transistors. These findings hold potential for broader exploitation of the OLET platform, where the device can now be driven by commercially available electronics, thus enabling flexible low-bias organic electronic devices. Full article

Ladder-type molecules, which possess an extended aromatic backbone, are particularly sought within the optoelectronic field. In view of the potential of the 14H-bis[1]benzothieno[3,2-b:2’,3’-h]carbazole core as a p-type semiconductor, herein we studied a set of two derivatives featuring a different alkylation patterning. The followed synthetic route, involving various sulfurated carbazole-based molecules, also resulted in a source of fluorophores with different emitting behaviors. Surprisingly, the sulfoxide-containing fluorophores substantially increased their blue fluorescence with respect to the nearly non-emitting sulfur counterparts. On this basis, we could shed light on the relationship between their chemical structure and their emission as an approach for future applications. Considering the performance in organic thin-film transistors, both bisbenzothienocarbazole derivatives displayed p-type characteristics, with hole mobility values up to 1.1 × 10⁻³ cm² V⁻¹ s⁻¹ and considerable air stability. Moreover, the role of the structural design has been correlated with the device performance by means of X-ray analysis and the elucidation of the corresponding single crystal structures. Full article

Organic light-emitting field-effect transistors (LEFETs) provide the possibility of simplifying the display pixilation design as they integrate the drive-transistor and the light emission in a single architecture. However, in p-type LEFETs, simultaneously achieving higher external quantum efficiency (EQE) at higher brightness, larger and stable emission area, and high switching speed are the limiting factors for to realise their applications. Herein, we present a p-type polymer heterostructure-based LEFET architecture with electron and hole injection interlayers to improve the charge injection into the light-emitting layer, which leads to better recombination. This device structure provides access to hole mobility of ~2.1 cm² V⁻¹ s⁻¹ and EQE of 1.6% at a luminance of 2600 cd m⁻². Most importantly, we observed a large area emission under the entire drain electrode, which was spatially stable (emission area is not dependent on the gate voltage and current density). These results show an important advancement in polymer-based LEFET technology toward realizing new digital display applications. Full article

In this review paper, we present a comprehensive summary of the different organic solar cell (OSC) families. Pure and doped conjugated polymers are described. The band structure, electronic properties, and charge separation process in conjugated polymers are briefly described. Various techniques for the preparation of conjugated polymers are presented in detail. The applications of conductive polymers for organic light emitting diodes (OLEDs), organic field effect transistors (OFETs), and organic photovoltaics (OPVs) are explained thoroughly. The architecture of organic polymer solar cells including single layer, bilayer planar heterojunction, and bulk heterojunction (BHJ) are described. Moreover, designing conjugated polymers for photovoltaic applications and optimizations of highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energy levels are discussed. Principles of bulk heterojunction polymer solar cells are addressed. Finally, strategies for band gap tuning and characteristics of solar cell are presented. In this article, several processing parameters such as the choice of solvent(s) for spin casting film, thermal and solvent annealing, solvent additive, and blend composition that affect the nano-morphology of the photoactive layer are reviewed. Full article

In recent years, active-matrix organic light-emitting diodes (AMOLEDs) has been the most popular display for portable application. To satisfy the requirement for the application of the portable display, the design of the compensating pixel circuit with the low-voltage driving and low-power consumption will be requested. In addition to the circuit with the design of the low-voltage driving, high-mobility thin-film transistors as driving device will be also necessary in order to supply larger driving current at low-voltage driving. Therefore, the study presents a new low-voltage driving AMOLED pixel circuit with high-mobility amorphous indium–zinc–tin–oxide (a-IZTO) thin-film transistors (TFTs) as driving device for portable displays with high resolution. The proposed pixel circuit can simultaneously compensate for the threshold voltage variation of driving TFT (ΔV_{TH_TFT}), OLED degradation (ΔV_{TH_OLED}), and the I-R drop of a power line (ΔV_DD). By using AIM-Spice for simulation based on fabricated a-IZTO TFTs with mobility of 70 cm²V⁻¹S⁻¹ as driving devices, we discovered that the error rates of the driving current were all lower than 5.71% for all input data when ΔV_{TH_TFT} = ±1 V, ΔV_DD = 0.5 V, and ΔV_{TH_OLED} = 0.5 V were all considered simultaneously. We revealed that the proposed 5T2C pixel circuit containing a high-mobility a-IZTO TFT as a driving device was suitable for high-resolution portable displays. Full article

An active-mode organic light-emitting diode (AMOLED) display on a fabric substrate is expected to be a prominent textile display for e-textile applications. However, the large surface roughness of the fabric substrate limits the aperture ratio—the area ratio of the organic light-emitting diode (OLED) to the total pixel area. In this study, the aperture ratio of the AMOLED panel fabricated on the polyethylene terephthalate fabric substrate was enhanced by applying a stacked-pixel structure, in which the OLED was deposited above the organic thin-film transistor (OTFT) pixel circuit layer. The stacked pixels were achieved using the following three key technologies. First, the planarization process of the fabric substrate was performed by sequentially depositing a polyurethane and photo-acryl layer, improving the surface roughness from 10 μm to 0.3 μm. Second, a protection layer consisting of three polymer layers, a water-soluble poly-vinyl alcohol, dichromated-polyvinylalcohol (PVA), and photo acryl, formed by a spin-coating processes was inserted between the OTFT circuit and the OLED layer. Third, a high mobility of 0.98 cm²/V∙s was achieved at the panel scale by using hybrid carbon nano-tube (CNT)/Au (5 nm) electrodes for the S/D contacts and the photo-acryl (PA) for the gate dielectric, enabling the supply of a sufficiently large current (40 μA @ V_GS = −10 V) to the OLED. The aperture ratio of the AMOLED panel using the stacked-pixel structure was improved to 48%, which was about two times larger than the 19% of the side-by-side pixel, placing the OLED just beside the OTFTs on the same plane. Full article

A facile solution-processing strategy toward well-ordered one-dimensional nanostructures of conjugated polymers via a non-solvent vapor treatment was demonstrated, which resulted in enhancements to the charge transport characteristics of the polymers. The amount of crystalline poly(3-hexylthiophene) (P3HT) nanofibers was precisely controlled by simply varying the exposure time of solutions of P3HT solutions to non-solvent vapor. The effects of non-solvent vapor exposure on the molecular ordering and morphologies of the resultant P3HT films were systematically investigated using ultraviolet-visible (UV-vis) spectroscopy, polarized optical microscopy (POM), grazing incidence X-ray diffraction (GIXRD), and atomic force microscopy (AFM). The non-solvent vapor facilitates the π–π stacking in P3HT to minimize unfavorable interactions between the poor solvent molecules and P3HT chains. P3HT films deposited from the non-solvent vapor-treated P3HT solutions exhibited an approximately 5.6-fold improvement in charge carrier mobility as compared to that of pristine P3HT films (7.8 × 10⁻² cm² V⁻¹ s⁻¹ vs. 1.4 × 10⁻² cm² V⁻¹ s⁻¹). The robust and facile strategy presented herein would be applicable in various opto-electronics applications requiring precise control of the molecular assembly, such as organic photovoltaic cells, field-effect transistors, light-emitting diodes, and sensors. Full article