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Dynamically Switching the Electronic and Electrostatic Properties of Indium Tin Oxide Electrodes with Photochromic Monolayers: Toward Photo-Switchable Optoelectronic Devices
摘要： The chemical modification of electrodes with organic materials is a common approach to tune the electronic and electrostatic landscape between interlayers in optoelectronic devices, thus facilitating charge injection at the electrode/semiconductor interfaces and improving their performance. The use of photochromic molecules for the surface modification allows dynamic control of the electronic and electrostatic properties of the electrode and thereby enables additional functionalities in such devices. Here, we show that the electronic properties of a transparent indium tin oxide (ITO) electrode are reversibly and dynamically modified by depositing organic photochromic switches (diarylethenes) in the form of self-assembled monolayers (SAMs). By combining a range of surface characterization and density functional theory calculations, we present a detailed picture of the SAM binding onto ITO, the packing density of molecules, their orientation, as well as the work function modification of the ITO surface due to the SAM deposition. Upon illumination with ultraviolet and green light, we observe a reversible shift of the frontier occupied levels by 0.7 eV, and concomitantly a reversible work function change of ca. 60 meV. Our results prove the viability of dynamic switching of the electronic properties of the electrode with external light stimuli upon modification with a monolayer of photochromic molecules, which could be used to fabricate ITO-based photo-switchable optoelectronic devices.
关键词： self-assembled monolayer,diarylethene,ITO,photochromic switch,interface electronic properties
更新于2025-11-14 14:32:36
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Hybrid bilayer gate dielectric-based organic thin film transistors
摘要： Organic thin film transistors (OTFTs) are key building blocks for flexible, low cost electronics systems. They provide a viable alternative for silicon-based electronics with added advantages of low cost and flexibility. However, few issues like high-operating voltage, low-switching speed, high-leakage current and reliability are still a challenge. The overall performance of an OTFT depends on organic semiconductors and gate dielectric interface. In this paper, we review the current status and trends in the choice of dielectric layer for OTFTs. As a starting point, the performance parameters of an OTFT and their dependence on the dielectric layer are briefly discussed. A variety of dielectric materials which includes high-k inorganic, organic, surface coated inorganics and nanocomposites are also presented. The advantages and drawbacks of each of these materials are discussed in detail. We reviewed the latest developments in the dielectric materials especially, self-assembled monolayers (SAMs), hybrid bilayers and nanocomposites. SAM-based OTFTs offer several advantages but shift in the threshold voltage remains a concern. Nanocomposites are a latest addition to the dielectric materials, which offer advantages like solution processing and improved dielectric constant but have a rough surface. A hybrid bilayer that incorporates the inorganic dielectric as a base layer and a thin polymer layer over it to improve the surface properties offers several desirable characteristics over the other choices. Hence, we propose that hybrid bilayer gate dielectrics shall play a pivotal role in improving the OTFT performance.
关键词： low-k organic,high-k inorganic,Organic thin film transistor,self-assembled monolayer,gate dielectric,hybrid bilayer
更新于2025-09-23 15:23:52
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Performance enhancement of inverted perovskite solar cells through interface engineering by TPD based bidentate self-assembled monolayers
摘要： Perovskite solar cells (PSCs) have recently appeared as a promising photovoltaic technology and attracted great interest in both photovoltaic industry and academic community. Numerous active researches related to the material processing and operational aspects of device fabrication are under progress since PSCs have a great potential for attaining higher performance compared to that of other solar cell technologies. In particular, interfacial engineering is a crucial issue for obtaining high efficiency in solar cells where perovskite absorber layer is deposited between hole and electron transport layers. In inverted type architecture, PEDOT:PSS is used as both hole transport layer and surface modifier; but unfortunately, this material bears instability due to its acidic nature. Thus, self-assembled monolayers (SAMs) not only are considered as suitable alternative, but also their application is regarded as an efficient and cost effective method to modify electrode surface since it provides a robust and stable surface coverage. In this context, we have employed two novel N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD) based SAM molecules to customize indium tin oxide (ITO) surface in inverted type PSCs. Furthermore, fine-tuning of spacer groups enables us to study device performance depending on molecular structure. This study proposes promising materials for anode interface engineering and provides a feasible approach for production of organic semiconductor based SAMs to achieve high performance PSCs.
关键词： Interface,ITO,TPD,Bidentate,Self-assembled monolayer,Perovskite solar cell
更新于2025-09-23 15:21:01
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Effect of the Interface Improved by Self-Assembled Aromatic Organic Semiconductor Molecules on Performance of OLED
摘要： This work focuses on characterization the performance of enhanced interface of organic light emitting diode (OLED) device by Self-assembled Monolayer (SAM) technique. SAM technique is popular in order to overcome the weak bonding at the organic/inorganic interface in OLED. New generation of SAM molecules, phenyl-benzoic-acid (PBA, 4-(9H-carbazol-9-il) benzoic acid (MZ39), 4-(2,5-di-2thienyl-1H-pyrrol-1-il) benzoic acid (MZ25) were coated on between Indium Tin Oxide (ITO). The two con?guration of ITO/SAM/TPD/Al and ITO/TPD/Al diode were fabricated as hole-only device to show the contribution of SAM layer on the hole mobility calculated by Space Charge Limited Current (SCLC) technique. The optical characterization of OLED devices with con?guration ITO/TPD/Alq3/Al and ITO/SAM/TPD/Alq3/Al was performed to see the effect of aromatic SAM molecules on the luminance and quantum ef?ciency. Especially, the SAM modi?ed OLED has a maximum luminance of 397 cd m?2. All devices containing SAM layer showed better performance than reference one.
关键词： Indium Tin Oxide (ITO),quantum efficiency,OLED,luminance,Space Charge Limited Current (SCLC),Self-assembled Monolayer (SAM)
更新于2025-09-23 15:21:01
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Choline Chloride-modified SnO2 Achieving High Output Voltage in MAPbI3 Perovskite Solar Cells
摘要： Choline chloride as a photosynthesis promoter is important for increasing plant yield, and we have found that it has a similar effect in perovskite solar cells (PSCs). Here, we propose the innovation of using molecular self-assembly methods to produce a choline chloride monolayer on the surface of the SnO2; this monolayer works as a passivation layer that reduces the surface oxygen vacancies and improves the performance of CH3NH3PbI3 (MAPbI3) PSCs. The MAPbI3 PSC based on SnO2 modified by choline chloride (Chol-SnO2) electron transport layer (ETL) achieves an optimal power conversion efficiency (PCE) of 18.90% under one solar illumination. The PCE is increased by 10% ~ 25% compared to the device without modification, and hysteresis is significantly reduced by eliminating the charge accumulation between the interface of the perovskite and ETL. More importantly, the MAPbI3 PSC based on Chol-SnO2 ETL exhibits a higher open-circuit voltage (VOC) of 1.145 V compared to the control device (1.071 V). This work provides a very simple and effective way to improve PSC performance, which has long-term significance for the sustainable development of energy.
关键词： self-assembled monolayer,choline chloride,SnO2,electron transporting layer,perovskite solar cells
更新于2025-09-23 15:21:01
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A new SERS substrate of self-assembled monolayer film of gold nanoparticles on silicon wafer for the rapid detection of polycyclic aromatic hydrocarbons
摘要： A facile and rapid method for the SERS detection of polycyclic aromatic hydrocarbons (PAHs) was reported. The Au colloids assemble to form gold nanoparticles (Au NPs) monolayer film at the air/water interface through the modification of n-dodecanethiol (DT), and then the film was directly transferred by tilt-lifting onto the silicon wafer to fabricate uniformed SERS substrate. PAHs could be preconcentrated into DT layer on the surface of the SERS substrate through the hydrophobic interaction, and detected by SERS. The linear range of detection for Benzo[a]-pyrene (B[a]P) is from 10-8 to 10-5 mol/L with a linearity (R2) of 0.92 to 0.99. The recovery rates range from 89.5% to 103.7%. The detection limit can reach the ng/L level. Pyrene (Pyr) and Chrysene (Chr) were also detected by SERS. The substrate had good stability, uniformity, reproducibility and reusability, which demonstrated that the DT-functionalized Au NPs film prepared by the self-assembly method at the air/water interface could be used as a reliable SERS candidate for the rapid analysis of PAHs.
关键词： self-assembled monolayer (SAM),air/water interface,SERS,polycyclic aromatic hydrocarbons (PAHs),gold nanoparticles (Au NPs)
更新于2025-09-23 15:21:01
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[IEEE ESSDERC 2018 - 48th European Solid-State Device Research Conference (ESSDERC) - Dresden, Germany (2018.9.3-2018.9.6)] 2018 48th European Solid-State Device Research Conference (ESSDERC) - Gated Four-Probe Method to Evaluate the Impact of SAM Gate Dielectric on Mobility in MoS2 FET
摘要： This study reports the interfacial engineering by means of SAM (Self-assembled monolayer)-based gate dielectric on channel mobility in molybdenum disulfide (MoS2) field-effect transistors (FETs). A gated four-probe method was implemented to eliminate the effect of contact resistance on channel mobility. The formation of SAM significantly plays an important role in the improvement of channel mobility as high as 19 cm2/Vs in MoS2 FETs because the superior interfacial properties can be realized in MoS2/SAM structure. This study opens up interesting direction of interface engineering for research in the applications and developments of 2-dimensional materials-based thin film devices.
关键词： FETs,Interface properties,Channel mobility,Self-assembled monolayer,MoS2
更新于2025-09-23 15:21:01
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Sensitive Detection of Dengue Virus Type 2 E-Proteins Signals Using Self-Assembled Monolayers/Reduced Graphene Oxide-PAMAM Dendrimer Thin Film-SPR Optical Sensor
摘要： In this work, sensitive detection of dengue virus type 2 E-proteins (DENV-2 E-proteins) was performed in the range of 0.08 pM to 0.5 pM. The successful DENV detection at very low concentration is a matter of concern for targeting the early detection after the onset of dengue symptoms. Here, we developed a SPR sensor based on self-assembled monolayer/reduced graphene oxide-polyamidoamine dendrimer (SAM/NH2rGO/PAMAM) thin film to detect DENV-2 E-proteins. Surface characterizations involving X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirms the incorporation of NH2rGO-PAMAM nanoparticles in the prepared sensor films. The specificity, sensitivity, binding affinity, and selectivity of the SPR sensor were then evaluated. Results indicated that the variation of the sensing layer due to different spin speed, time incubation, and concentration provided a better interaction between the analyte and sensing layer. The linear dependence of the SPR sensor showed good linearity (R2 = 0.92) with the lowest detection of 0.08 pM DENV-2 E-proteins. By using the Langmuir model, the equilibrium association constant was obtained at very high value of 6.6844 TM?1 (R2 = 0.99). High selectivity of the SPR sensor towards DENV-2 E-proteins was achieved in the presence of other competitors.
关键词： optical sensor,E-proteins,SPR sensor,PAMAM dendrimer,reduced graphene oxide,dengue virus,self-assembled monolayer
更新于2025-09-23 15:19:57
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Tuning the Emission Colors of Self-Assembled Quantum Dot Monolayers via One-Step Heat Treatment for Display Applications
摘要： Homogeneously self-assembled colloidal semiconductor quantum dot monolayers (QD-SAMs) over large areas are promising materials for thin film optoelectronic device applications, especially for display. Although tuning of emission colors from QDs is generally achieved during wet chemical synthesis and before monolayer formation, we propose in this study a simple and effective method to adjust emission colors after the formation of QD-SAMs by a simple one-step heat treatment. CdSe-based core/shell or core/double shell structured QDs (CdSe/ZnS, CdSe/CdZnS, and CdSe/CdS/ZnS) covered with an optimal set of hydrophobic ligands can form homogeneous and stable QD-SAMs at the air-water interface. The QD-SAMs are subsequently transferred onto hydrophobized glass substrates by the Langmuir-Schaefer (LS) method and thermally treated in air. We found a blueshift of more than 35 nm for the emission wavelength (red to green) by a thermal treatment at 280 °C for 150 min with CdSe/ZnS QD-SAMs. The color can be adjusted by changing the heating temperature and the treatment time. The wavelength shift is in the order of CdSe/ZnS(4L) > CdSe/ZnS(6L) = (CdSe/CdZnS) > (CdSe/CdS/ZnS). The energy dispersive X-ray (EDX) microanalysis of a single QD reveals that the blueshift is mainly caused by atomic diffusion-induced alloying of core/shell type QDs. The main problem of this method is the decreasing emission intensity caused by oxidation during the heat treatment; however, this problem can be solved by use of a SiO2 protective coating on the QD-SAMs. We believe that this simple technique is useful for manufacturing RGB-colored ultrathin QD-SAM films for QDs displays such as QD film display, QD color-filter display, and QD light emitting diode.
关键词： QD Display,Quantum dots,Color tuning,Self-assembled monolayer,atomic diffusion-induced alloying,Thermal treatment
更新于2025-09-23 15:19:57
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Immobilization of DNA on Quartz Crystal Microbalance Sensor Modified with Self-Assembled Monolayer of Thiol Derivative
摘要： In this study, we investigated the direct detection of DNA, without pretreatment, using a quartz crystal microbalance (QCM) sensor. This sensor is modified by a self-assembled monolayer of a thiol derivative that has an amino group as the terminal functional group. Contact angle values and the attenuated total reflectance Fourier transform infrared (ATR/FT-IR) spectra of the QCM sensors after immersion into an ethanol solution of thiol derivatives clearly showed that self-assembled monolayers of the derivatives were formed on the QCM sensors. Although QCM measurements using unmodified and carboxylic group-modified sensors could not detect DNA-Na salt, the sensor modified with amino groups could detect the DNA. This system can be used for the analysis of the interaction between DNA and DNA-binding proteins.
关键词： DNA,thiol derivative,quartz crystal microbalance,self-assembled monolayer
更新于2025-09-23 15:19:57