Interfacial Modification of NiO_(x)by Self-assembled Monolayer for Efficient and Stable Inverted Perovskite Solar Cells

NiO_(x)as a hole transport material for inverted perovskite solar cells has received great attention owing to its high transparency,low fabrication temperature,and superior stability.However,the mismatched energy levels and possible redox reactions at the NiO_(x)/perovskite interface severely limit the performance of NiO_(x) based inverted perovskite solar cells.Herein,we introduce a p-type self-assembled monolayer between NiO_(x)and perovskite layers to modify the interface and block the undesirable redox reaction between perovskite and NiO_(x)The selfassembled monolayer molecules all contain phosphoric acid function groups,which can be anchored onto the NiOr surface and passivate the surface defect.Moreover,the introduction of self-assembled monolayers can regulate the energy level structure of NiO_(x),reduce the interfacial band energy offset,and hence promote the hole transport from perovskite to NiO_(x)layer.Consequently,the device performance is significantly enhanced in terms of both power conversion efficiency and stability.

Factors resisting protein adsorption on hydrophilic/hydrophobic self-assembled monolayers terminated with hydrophilic hydroxyl groups

The hydroxyl-terminated self-assembled monolayer(OH-SAM),as a surface resistant to protein adsorption,exhibits substantial potential in applications such as ship navigation and medical implants,and the appropriate strategies for designing anti-fouling surfaces are crucial.Here,we employ molecular dynamics simulations and alchemical free energy calculations to systematically analyze the factors influencing resistance to protein adsorption on the SAMs terminated with single or double OH groups at three packing densities(∑=2.0 nm^(-2),4.5 nm^(-2),and 6.5 nm^(-2)),respectively.For the first time,we observed that the compactness and order of interfacial water enhance its physical barrier effect,subsequently enhancing the resistance of SAM to protein adsorption.Notably,the spatial hindrance effect of SAM leads to the embedding of protein into SAM,resulting in a lack of resistance of SAM towards protein.Furthermore,the number of hydroxyl groups per unit area of double OH-terminated SAM at ∑=6.5 nm^(-2) is approximately 2 to 3 times that of single OH-terminated SAM at ∑=6.5 nm^(-2) and 4.5 nm^(-2),consequently yielding a weaker resistance of double OH-terminated SAM towards protein.Meanwhile,due to the structure of SAM itself,i.e.,the formation of a nearly perfect ice-like hydrogen bond structure,the SAM exhibits the weakest resistance towards protein.This study will complement and improve the mechanism of OH-SAM resistance to protein adsorption,especially the traditional barrier effect of interfacial water.

Dimethyl acridine-based self-assembled monolayer as a hole transport layer for highly efficient inverted perovskite solar cells

Self-assembled monolayers(SAMs)have recently emerged as excellent hole transport materials in inverted perovskite solar cells(PSCs)owing to their ability to minimize parasitic absorption,regulate energy level alignment,and passivate perovskite defects.Herein,we design and synthesize a novel dimethyl acridinebased SAM,[2-(9,10-dihydro-9,9-dimethylacridine-10-yl)ethyl]phosphonic acid(2PADmA),and employ it as a hole-transporting layer in inverted PSCs.Experimental results show that the 2PADmA SAM can modulate perovskite crystallization,facilitate carrier transport,passivate perovskite defects,and reduce nonradiative recombination.Consequently,the 2PADmA-based device achieves an enhanced power conversion efficiency(PCE)of 24.01%and an improved fill factor(FF)of 83.92%compared to the commonly reported[2-(9H-carbazol-9-yl)ethyl]phosphonic acid(2PACz)-based control device with a PCE of 22.32%and FF of 78.42%,while both devices exhibit comparable open-circuit voltage and short-circuit current density.In addition,2PADmA-based devices exhibit outstanding dark storage and thermal stabilities,retaining approximately~98%and 87%of their initial PCEs after 1080 h of dark storage and 400 h of heating at 85°C,respectively,both considerably superior to the control device.

Preparation and Characterization of SrTiO_3 Thin Film on Functional Organic Self-Assembled Monolayers

SrTiO3 thin film was successfully prepared on the functionalized organic self-assembled monolayers（SAMs） by the Liquid Phase Deposition（LPD） method.The as-prepared samples were characterized by X-ray diffraction（XRD）,atomic force microscope（AFM）,scanning electron microscopy（SEM） and metallographic microscope.Measurement of contact angle showed that the hydrophobe substrate was changed into hydrophile by UV irradiation.AFM photographs of octadecyl-trichloro-silane self-assembled monolayer（OTS-SAM） surface approved that UV irradiation did change the morphology of OTS monolayer and provided evidence for the conversion of hydrophilic characteristic.Photographs of Metallographic Microscope showed that OTS-SAM had an active effect on the deposition of SrTiO3 thin film.XRD and SEM indicated that the thin film was of pure cubic phase SrTiO3 and composed of nanosized grains with a size in the range of 100-500 nm.The formation mechanism of the SrTiO3 film was proposed.

Dielectric Properties of Self-assembled Monolayers of Dithiols

Dielectric properties of dithiol self-assemble monolayers （SAMs） under ac electric field were presented, Using a Hg-SAM/SAM-Ⅱg junction, the ac impedances of dithiol SAMs were measured using a sinusoidal perturbation of 30 mV （peak to-peak） with the frequency ranging from 1 Hz to 1 MHz at zero bias. The contributions from dithiol SAMs and solvent interlayers were separated due to their different behaviors at ac impedance. The peak position in the loss spectra （the plot; of tgδ vs. frequency） moves to low frequcney with the incrcase of chain length of dithiols. Using a correlation of peak position with the chain length, the active energies of 23-39 meV for dithiol SAMs of C6-C10 under an ac electric field were derived,

Chitosan/Sodium Alginate Multilayer pH-Sensitive Films Based on Layer-by-Layer Self-Assembly for Intelligent Packaging

The abuse of plastic food packaging has brought about severe white pollution issues around the world.Developing green and sustainable biomass packaging is an effective way to solve this problem.Hence,a chitosan/sodium alginate-based multilayer film is fabricated via a layer-by-layer(LBL)self-assembly method.With the help of superior interaction between the layers,the multilayer film possesses excellent mechanical properties(with a tensile strength of 50 MPa).Besides,the film displays outstanding water retention property(blocking moisture of 97.56%)and ultraviolet blocking property.Anthocyanin is introduced into the film to detect the food quality since it is one natural plant polyphenol that is sensitive to the pH changes ranging from 1 to 13 in food when spoilage occurs.It is noted that the film is also bacteriostatic which is desired for food packaging.This study describes a simple technique for the development of advanced multifunctional and fully biodegradable food packaging film and it is a sustainable alternative to plastic packaging.

Tunneling Electron Induced Fluorescence from Single Porphyrin Molecules Decoupled by Striped-Phase Octanethiol Self-assembled Monolayer

We investigate tunneling electron induced luminescence from isolated single porphyrin molecules that are decoupled by striped-phase self-assembled monolayer of octanethiol from the underneath Au（111） substrate. Intrinsic single-molecule electroluminescence has been realized by such decoupling at both bias polarities. The photon emission intensity acquired from the molecular lobe is found stronger than that from the molecular center. These re- sults provide useful information on the understanding of electroluminescent behavior and mechanism in molecular tunnel junctions.

Novel self-assembled films of La-based phosphonate 3-aminopropyltriethoxysilane

Silane coupling reagent (3-aminopropyltriethoxysilane (APTES)) was prepared on single-crystal silicon substrates to form two-dimensional self-assembled monolayer (SAM). The terminal-NH2 groups in the film were in situ phosphorylated to -PO(OH)2 group to endow the film with good chemisorption ability. Then La-based thin films were deposited on phosphorylated APTES-SAM in order to make good use of the chemisorption ability of -PO(OH)2 groups. The thickness of the film was determined with ellipsometer, while phase transformation and surface morphology, surface energy, phase composition were analyzed by means of atomic force microscope (AFM), contact angle measurements and X-ray photoelectron spectroscopy (XPS). The results indicated that the terminal-NH2 groups could be completely transformed into desirable-PO(OH)2 groups after phosphorylation of APTES-SAM. Detailed XPS analysis of the La3+ peaks revealed that lanthanum element existed in the films in different states. As a result, conclusion could be made that lanthanum reacted with -PO(OH)2 groups on the surface of the substrate by chemical bond which would improve the bonding strength between the film and silicon substrate. Since the La-based thin films were well adhered to the silicon substrate, it might find promising application in the surface-modification of single-crystal Si and SiC in microelectromechanical systems (MEMS).

The lipase monolayer film self-assembly on the negatively charged poly(ethylene terephthalate) substrate

The PET-CO2- film was prepared and the lipase was assembled on the surface of the PET-CO2- substrate The structure at the surface and activity of lipase/PET monolayer were studied by ATR-FTIR and AFM, and other methods.

Self-assembly to monolayer graphene film with high electrical conductivity

Monolayer chemically converted graphene （CCG） nanosheets can be homogeneously self-assembled onto silicon wafer modified by 3-aminopr- opyl triethoxysilane （APTES） to form very thin graphene film. The CCG film was characterized by FT-IR, XRD, SEM, TEM and AFM. Results show that CCG sheets formed monolayer film after assembled onto silicon wafer and there is a very tight chemical bond between sheets and wafer. Furthermore, the electrical measurements revealed that the monolayer graphene film has an excellent electrical conductivity.

Attachment of tyrosinase on mixed self-assembled monolayers for the construction of electrochemical biosensor

A mixed self-assembled monolayers （SAMs） of thioctic acid （T-COOH） and thioctic acid amide （T-NH2） were used to immobilize tyrosinase for fabricating biosensor. The results showed that the mixed SAMs prepared from solution at the ratio of 1：4 provided an excellent microenvironment for enzymatic reaction between tyrosinase and substrate. The biosensor exhibited a fast response and high sensitivity for sensing substrate.

Preparation and characterization of 3-mercaptopropyl trimethoxysilane self-assembled monolayers

Silane coupling regent （3-mercaptopropyl trimethoxysilane （MPTS）） was prepared on the single-crystal silicon substrate to form 2-dimensional self-assembled monolayers （SAMs）. The growth behavior of SAMs formed from 3-MPTS was investigated using atomic force microscopy （AFM）, contact angle measurements, ellipsometry, and X-ray photoelectron spectroscopy （XPS）. The formation behavior of MPTS SAMs was investigated by a series of AFM images and the roughness of MPTS SAMs on silicon substrates with the assembling time from 1 min to 24 h. The water contact angle measurements indicated the growth behavior of MPTS that correlated with the AFM measurements at different immersion times, too. The chemical states of the typical elements in the MPTS SAMs were analyzed using X-ray photoelectron spectroscopy. The results show that MPTS is self-assembled on the substrate.

FABRICATION AND AFM/FFM STUDIES OF C_(60)-CONTAINING POLYELECTROLYTE SELF-ASSEMBLED FILMS

An initial investigation on the roughness and frictional properties of the self-assembled thin films from polyelectrolytes is presented. Star-shaped C-60-Poly(styrene-maleic anhydride) was successful prepared. The multilayer thin films have been fabricated on mica with diazoresin as the cationic polyelectrolyte and hydrolyzed star-shaped C-60-poly(styrene-maleic anhydride) as the anionic polyelectrolyte via self-assembly technique. The crosslinking structure of the films is formed from the conversion of ionic bond to covalent bond after UV irradiation. AFM/FFM investigations provide insights into the roughness and frictional properties on a microscale. The roughness depends strongly on the number of film layers in the case of C-60-containing films. The frictional forces of the films exhibited a well behaved non-linear relationship in response to the change of applied load. It supports the prediction of enhanced load-bearing property Of C60-containing thin films.

Enhanced Hole-Injection Property in an OLED with a Self-assembled Monolayer of Hole-Transporting TPD on Thin Au as the Anode

A thioester-functionalized triphenylamine hole-transporting molecule （TPD-SAc） was synthesized and self-assembled to form a monolayer on an ultra-thin Au film supported on indium-tin oxide glass. The modified surface was characterized by aqueous contact angle, ellipsometer, atomic force microscopy, X-ray photoelectron spectroscopy, and ultraviolet pho- toelectron spectrometer to substantiate the formation of compact and pinhole-free monolayers. The modified organic light emitting diode device [indium-tin oxide/Au （5 nm）/self-assembled monolayers （SAM）/TPD （50 nm）/Alq3 （40 nm）/TPBI （15 nm）/LiF （1 nm）/A1 （100 nm）] showed a luminance of 7303.90 cd/m^2 and a current efficiency of 8.49 cd/A with 1.78 and 2.29-fold increase, respectively, compared to the control device without SAM. The improvements were attributed to the enhanced compatibility of the organic-inorganic interface, matched energy level by introduction of an energy mediating step and superior hole-injection property of SAM molecules.

Characterization and tribological investigation of self-assembled trimethoxysilyl-functionalized poly(phthalazinone ether ketone)thin films on glass substrates

Trimethoxysilyl-functionalized PPEK（PKGS） films had been designed to serve as wear resistant coatings for silicon surfaces. These surface films were formed by a dip-coating technique applied to self-assembled monolayers（SAMs）.The formation and wetting behavior of PKGS films were characterized by means of contact angle measurement.The friction coefficient of the film prepared is very low（about 0.1）,and the anti-wear behavior is good,with a lack of failure after sliding over 1800 s.

Electrochemical Behavior and Determination of Trifluoperazine at Decanethiol Self-Assembled Monolayer Modified Gold Electrodes

The electrochemical behavior of trifluoperazine at decanethiol self-assembledmonolayer (SAM) modified gold electrodes (i. e. C_(10) H_(21) SH/Au) has been studied,Trifluoperazine can effectively accumulate on C_(10) H_(21) SH/Au electrodes and generate asensitive anodic peak at about 0.63 V (vs. SCE) in 0.05 mol/L pH 9.4 Na_2 B_4 O_7 buffer solution.Under the selected conditions, the anodic peak current was linear to trifluoperazine concentrationin the range of 5.0 X 10^(-7)-3.O X 10^(-3) mol/Lwith correlation coefficient of 0.997, thedetection limit was 3.0 X 10^(-5) mol/L. This method was applied to the determination oftrifluoperazine in drug samples and the recovery was 97.3%-104.0% It was found that sodium dodecylsulfate (SDS) could make the anodic peak current increase. In the presence of SDS, the peak at about0.63 V turned into two peaks, resulting from the change of the electrochemical mechanism.

The Molecular Recognition Characteristics of ω-MercaptoMethoxy Poly(Ethylene Glycol) Self-assembled Monolayer at Gold Electrode and the Detection of Dopamine in Serum

Self assembled monolayers (SAMs) of to-mercapto methoxy poly(ethylene glycol)(MPEG) on gold electrode were used as a means to detect dopamine. Dopamine (DA) had good response at the MPEG film electrode and ascorbic acid (AA) was repelled from the SAMs. TheMPEG film is a biocompatible film, there was no adsorption of biosample and no inactivation atelectrode surface when it was used to detect DA in biosamples.

Characterization of Self-assembled Monolayers on Gold Electrode Using Electrochemical Quartz Crystal Microbalance

The electrochemical quartz crystal microbalance (EQCM) is used to investigate the characteristics of the thiolated self-assembled monolayer(SAM) on gold surface.A 5MHz QCM element serves as both the mass-sensitive sensor and the working electrode of the electrochemical system.The 6-mecapto-1-hexanol and and the 16-mer oligonucleotide with a mercaptohexyl group at the 5'-phosphate end are utilized to form the SAM on the gold electrode.The frequency response of the QCM during cyclic voltammetry (CV) scanning and cbronoamperometry are recorded together with the electrochemical current.The experimental results indicates that the frequency response is more sensitive to the surface coverage.Therefore,the response of the EQCM reveals more details of the SAM on gold electrode.It is especially useful for analysing the immobilization quality,such as probe orientation and coverage,of the SAM.

Characterization and tribological investigation of self-assembled MPTS-MPTES/RE composite films

γ-mercapto-propyl trimethoxysilane （MPTS） and γ-methacryloxy propyltrimethoxysilane （MPTES） were self-assembled on a hy- droxylated glass substrate to form a two-dimensional organic monolayer （MPTS-MPTES SAM）. The terminal thiol groups （-SH） in the MPTS-MPTES SAM were in-situ oxidized into sulfonic acid groups （-SO3H） to endow the film with good chemisorption ability. Then rare earth （RE） （lanthanum-based） composite thin films were prepared by self-assembly technique based on the as-prepared SAM, taking advantage of the chemisorption ability of the sulfonic acid groups. Automatic force microscope （AFM）, X-ray photoelectron spectrometry （XPS）, contact angle measurement and ellipsometer were used to characterize MPTS-MPTES/RE composite films. The macrofriction and wear behaviors of the films sliding against an AISI-52100 steel ball were examined on a unidirectional friction and wear tester, and the worn surface morphologies were observed on an AFM. The results showed that MPTS-MPTES/RE films had a low friction coefficient （0.09） and a long wear life （5980 sliding pass） at a light load （50 mN）. It indicated that the superior tribological properties of the MPTS-MPTES/RE composite films were attributed to the special characteristic of RE elements, the mobility of the films and good bonding strength.

Self-Assembled Monolayer of Lipoic Acid on Gold and Its Application to Rapid Determination of 2, 3, 7, 8-Tetrachlorodibenzo-p-Dioxin

Lipoic acid (LA) has received great attention in the area of gold surface functionalization. In this study, LA was employed as a linker for the attachment of antibody to the gold surface of surface plasmon resonance (SPR) chip. By using this chip in a homemade SPR immunosensor, low molecular weight compound 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) can be detected at a low level of 0.01 ng/mL. There is a good linear relationship(R2 =0.943 1) between the results of SPR biosensor and enzyme-linked immunosorbent assay(ELISA).