Effect Of Interface Modification Research Articles

Effect of interface modification in polymer solar cells: An in-depth investigation of the structural variation of organic dye for interlayer material

In order to investigate the effect of the structural variation of interlayer materials on the photovoltaic properties of polymer solar cells (PSCs) in depth, we designed and synthesized three types of small-molecule dyes with a structure of 1,1′-bis(1-alkyl)-4,4′-bipyridine-1,1′-diium benzenesulfonate (V-alkyl-OTs). Here, the alkyl groups were butyl, hexyl, and dodecyl, which denoted as C4, C6, and C12, respectively. The magnitudes dipole moments will be in the order of V–C4-OTs < V–C6-OTs < V–C12-OTs due to the increased the alkyl chain length from C4 to C12. The work function of the ZnO layer with V-alkyl-OTs is exhibited to depend on the alkyl chain length, indicating that a Schottky barrier can be tuned by the size of cation part. Thus, The power conversion efficiencies (PCEs) of the PSCs based on the blend of PTB7 and PC71BM as the photoactive layer with V-alkyl-OTs were improved over for the device with pristine ZnO (without V-Alkyl-OTs) from 7.6% (short circuit current (Jsc) = 16.0 mA/cm2, open circuit voltage (Voc) = 0.72 V, fill factor (FF) = 65.6%) to 8.1% (V–C4-OTs, Jsc = 16.8 mA/cm2, Voc = 0.73 V, FF = 65.9%), 8.3% (V–C6-OTs, Jsc = 17.2 mA/cm2, Voc = 0.72 V, FF = 67.3%), and 8.6% (V–C12-OTs, Jsc = 18.0 mA/cm2, Voc = 0.72 V, FF = 66.4%). The enhancement of the PCE is strongly related to the alkyl chain length, and the major contribution was by the improvement of the Jsc due to the reduction in the energy offset at the cathode interface.

The effect of oxygen pretreatment at hetero-interface on the photovoltaic properties of MoS2/Si heterojunction solar cells

In this work, we modify the n-type MoS2/p-type Si heterojunction interface by oxygen pretreatment at the initial stage of MoS2 films deposition. Such a facile pretreatment process has effective effect on the defects recombination reduction and band alignment at the MoS2/Si heterojunction interface. By adding the O2 into the sputtering gases and lasting 3-10 s, the oxygen vacancy defects at the hetero-interface significantly decreased and the built-in electric field greatly increased and exceeded 600 mV, which was benefit for reducing defects recombination losses and improving carrier extraction at MoS2/Si interface. Hence, the enhanced MoS2/Si heterojunction solar cells performance (Voc of 243 mV, FF of 58.71 and Jsc of 32.35 mA/cm2) were obtained with the optimized conversion efficiency of 4.62%. While, if the pre-sputtering time was over 20 s, the interface vacancy defects increased instead and the built-in potential was reduced to 582.7 mV, which leads to the poor carrier transport at MoS2/Si interface and adversely affects the cells electrical performance. The results demonstrate that the appropriate oxygen pretreatment could be a new and efficient way to enhance the photovoltaic properties of the MoS2/Si heterojunction solar cells by the interface modification effect.

Enhanced photovoltaic property and stability of perovskite solar cells using the interfacial modified layer of anatase TiO2 nanocuboids

The substrates were significant for fabricating the high performance and outstandingly stable perovskite solar cells (PSCs) due to the influences of films growth and pores filling. In this paper, we study the effects of interface modification with TiO2 nanoparticles (NPs) and nanocuboids (NCs) synthesized by the TiCl4 and NaF/TiCl4 solution, prepared on nanorods (NRs) substrates, on the PSCs performance. The devices modified with NPs and NCs exhibit power conversion efficiency (PCE) of 12.97% and 15.56%, respectively, which are 1.3 and 1.5 times greater than that of the untreated cell (10.29%). By carefully analyze the photovoltaic parameters, the improvements in the open-circuit voltage (Voc) and fill factor (FF) can be attributed to the optimization of the interfacial properties of perovskite-titania and the quality of perovskite films after the surface treatment. The novel TiO2 NCs obtained by NaF/TiCl4 treatment were found to expose highly reactive (001) facets, which may promote the absorption of perovskite materials due to the more effective area, resulting in the increment of short-circuit current density (Jsc) compared to simplex TiCl4 treatment. In addition, the device modified by the NCs shows the higher stability in the air atmosphere than other devices.

Combined effects of interface modification and nano‐reinforcement via nano‐enhanced interphase in hybrid‐fabric composites for tribological applications

Hybrid Nomex/PTFE (Polytetrafluoroethylene) fabric composites have demonstrated sufficient potential in tribological field due to their prominent mechanical and self‐lubricating capabilities. However, the poor fabric‐matrix interfacial adhesion and weak bonding of transfer‐film to counterface are still the bottlenecks for practical applications of these materials. Herein, growth of ZnO nanowires onto the surface of hybrid Nomex/PTFE fabric based on air‐plasma treatment was developed, aiming at enhancing the fabric‐matrix interfacial performance using a mild hydrothermal method. Mechanical testing showed significant improvement in the interfacial adhesion strength, while retaining the full mechanical strength and flexibility of pristine hybrid‐fabric. More importantly, the ZnO nanowires, released onto the interface during sliding process, participated in the tribo‐physical actions contributing to the formation of a uniform and tenacious transfer‐film. It is thought, therefore, that the ZnO‐enhanced interphase has the dual effects of interface modification and nano‐reinforcement of transfer‐film. As a result, the tribological performance of hybrid‐fabric–ZnO nanowires composites presented a considerable enhancement under varied load conditions. POLYM. COMPOS., 40:3383–3392, 2019. © 2019 Society of Plastics Engineers

Germanene Growth on Al(111): A Case Study of Interface Effect

Using density functional theory calculations, we have studied germanene growth on Al(111) in detail. According to the polygons in GeN (N = 1–12) structures on a substrate, three structural growth modes are studied, which would lead to the growths of single-atom-thick hexagonal lattice, Kagome lattice, and buckled hexagonal superlattice germanenes. The buckled superlattices grown on pure Al(111) could reproduce the experimental scanning tunneling microscopy images, which however do not have good energetic and thermal stabilities. Detailed energy analyses suggest the possibility of forming an Al2Ge surface alloy, on which the growths of the buckled superlattices turn to be preferable. Furthermore, such superlattice configurations become energetically and thermally stable. Their adhesive energy is ∼83 meV/A2, which could be further decreased by hydrogenation to facilitate their separations from the Al2Ge substrate. These studies highlight the effects of interface modification on tuning two-dimensional materi...

Large Scale Coarse-Grained Molecular Dynamics Simulations of Void Formations in Rubbers for Tires

Because wear-resistant is one of the demanded properties of tires used for motor cars due to the growing demand for resource saving, industrial developments toward such a direction have been attempted. However, attrition of rubber has not been fully elucidated yet. In this study, we have performed large scale coarse-grained molecular dynamics simulations of rubber to analyze the fracture that occurs inside the rubber from molecular level. In our model, the polymer molecules were represented by the coarse-grained beads-spring model. The filler particles were represented as clusters of beads, and their dispersion was reconstructed from the three-dimensional transmission electron microscope images of actual rubber. We added the coupling agent between polymers and particles to see the effect of interface modification. To reasonably accommodate the particle dispersion, we construct the large simulation box containing more than 130 million beads. After the sufficient equilibration, instantaneous stretch toward one direction was applied, whereas the box dimension for the other directions was fixed. During the relaxation process, dynamics of void formation was observed. As a result, we have found that a specific coupling agent can suppress the void formation at the interface. Owing to the result, we have developed the new tire product with high wear-resistance.

Enhancing the efficiency of low-temperature planar perovskite solar cells by modifying the interface between perovskite and hole transport layer with polymers

In this work, planar perovskite solar cells (PSCs) based on CH3NH3PbI3 perovskite layer and low-temperature processed TiO2 have been fabricated. Polymers including poly(methylmethacrylate) (PMMA), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-pheny- lenevinylene] (MEH-PPV) and polyethylene glycol (PEG) in chlorobenzene solution have been selected to modify the interface between perovskite and hole transport layer (HTL), respectively. The concentrations of the three polymer solutions have been optimized. The effect of interfacial modification by different polymer solutions on the photoelectric properties of perovskite layer and the performance of PSCs has been systematically investigated. The microstructure and photoelectric properties of the modified perovskite films has been systematically studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), conducting force microscopy (CFM) and Kelvin probe force microscopy (KPFM). The results reveal that the modified perovskite films with tetrahedral perovskite structure have lager grain size, lower roughness and better photoelectric properties compared with the reference sample. The electron trap state density (Dtrap), charge extraction, carrier transfer and recombination process in the PSCs have been investigated by current-voltage (I-V) characteristic curves, steady-state photoluminescence (PL), photo-voltage decay and electrochemical impedance spectroscopy (EIS). The results indicate that the polymeric interface modification at the optimum concentration can reduce the Dtrap, promote the charge transfer and suppress carrier recombination, resulting in the improved performance of PSCs. All of the modified PSCs at an optimum concentration exhibit the improved fill factor (FF) and open circuit voltage (Voc), thus the power conversion efficiency (PCE) is enhanced to over 17% from 15.49%.

Hybrid silane-treated glass fabric/epoxy composites: tensile properties by micromechanical approach

The effect of interface modification on the interfacial adhesion and tensile properties of glass fabric/epoxy composites was evaluated in two directions of 0° and +45°. Herein, the glass fabric surface was modified by colloidal nanosilica particles and by a new blend of silane-coupling agents including both reactive and non-reactive silanes. Composite samples with high strength and toughness were obtained. A simultaneous improvement of tensile strength and toughness was observed for an epoxy composite reinforced with a hybrid-sized glass fabric including silane mixture and nanosilica. In fact, the incorporation of colloidal silica into the hybrid sizing dramatically modified the fiber surface texture and created mechanical interlocking between the glass fabric and resin. The results were analyzed by the rule of mixtures (ROM), Halpin–Tsai (H–T), and Chamis equations. It was found that the ROM equations provided approximate upper bound values for all investigated composite samples. In the samples containing nanosilica, the shear and elastic moduli values calculated by the Chamis and ROM equations showed good agreement with those obtained from experiments. However, in other samples, the values calculated by the H–T equation showed a better agreement with the experimental data. The analysis of fracture surfaces indicated that both silane and nanosilica particles had influence on the mode of failures at the interface.

Effects of interface modification on electrical and optoelectronic properties of p-type CuAlO2/n-type Si heterojunction devices

The effect of interface modification on the electrical properties of heterojunction diodes based on the p-type CuAlO2 and n-type Si is investigated. Compared with the CuAlO2/Si device without H2O2 treatment, the CuAlO2/Si device with H2O2 treatment exhibits a better rectification behavior. The forward-bias current–voltage characteristics can be explained on the basis of the space charge limited current theory for CuAlO2/Si device without H2O2 treatment. However, the thermionic emission model is the dominant process in this fabricated CuAlO2/Si device with H2O2 treatment. The enhanced device performance is mainly the result of the formation of Si–O bonds that serves to reduce the number of interface states. The effect of H2O2 treatment on the sensitivity to solar irradiation and the response time for CuAlO2/Si devices is also studied. An increase in the values of photocurrent and photosensitivity is attributed to the rectification performance improvement that results from interface passivation.

Enhanced Charge Transport in ZnO Nanocomposite Through Interface Control Using Multiwall Carbon Nanotubes

Hybrid strategy of ZnO with carbon nanotube (CNT) has been attempted, and synergistic effects have been demonstrated in ZnO‐CNT hybrid nanostructures owing to the advantageous effects of interface modification on the charge transport process. Here, we report the effects of interface control using multiwall CNTs (MWCNTs) on the charge transport properties in Al‐doped ZnO (AZO) nanocomposite. Although the AZO‐MWCNT nanocomposite is composed of numerous nanograins, it shows single crystalline charge transport behavior due to significantly weakened grain‐boundary scattering at room temperature. The dominant charge transport mechanism is converted from lattice vibration scattering to grain‐boundary scattering at 873 K due to the variation in the charge distribution at the grain boundary. The results demonstrate that interface control using carbon nanomaterials has a significant effect on the charge transport behavior in AZO nanocomposite.

Effect of interface modification by Cu-coated W powders on the microstructure evolution and properties improvement for Cu–W composites

Abstract The effects of interfacial bond and homogeneous microstructure on the physical properties of Cu–W composites have been investigated. To acquire strong interfacial bond and homogeneous microstructure, different modified W powders have been designed, which W powders were coated with different Cu contents using electroless plating method. The results showed that by increasing the Cu content of the coating, the microstructure of Cu–W composites becomes homogeneous, and the physical properties, including thermal, electrical and mechanical properties, improved greatly. When 20Cu@W composite powders were used to fabricate Cu–W composites, the physical properties reached the optimal values: The thermal conductivity was 239 W/(m·K) which was close to the theoretical vaule of 240 W/(m·K), the electrical conductivity was 50.6%IACS, coefficient of thermal expansion was the minimum value of 7.3 × 10 − 6 /K, the bending strength and Vickers hardness were 976.7 MPa and 224.8 HV, respectively. These optimal values were much higher than those of mixed Cu–W composites. The properties enhancement of Cu–W composites is attributed to the strong interfacial bond between Cu and W and homogeneous microstructure. This enhancement effect was strengthened by increasing the coating's Cu content, resulting in the continuous improvement of the physical properties.

Biocomposites Based on Rice Husk Flour and Recycled Polymer Blend: Effects of Interfacial Modification and High Fibre Loading

Biocomposites were prepared with rice husk flour (RHF) (raw and alkali-treated) in a recycled polymer blend (RPB) using a co-rotating twin screw extruder. Modifications to the composite were carried out through fibre surface treatment with 4 wt.% sodium hydroxide (NaOH) and 3 wt.% maleic anhydride polyethylene (MAPE) coupling agent. Fourier transform infrared (FTIR) analyses of raw and NaOH-treated RHF were performed. The effects of the interfacial modification (MAPE or/and NaOH) and filler loading (50 to 80 wt.%) on the mechanical, physical, and morphological properties were investigated. Improvements in the tensile strength and Young's modulus as well as reduction in water absorption and water loss were observed for raw RHF composites incorporated with MAPE. Alkalisation of fibres resulted only in an enhancement in elongation and impact strength. The composite with 70 wt.% RHF modified with only MAPE exhibited the highest tensile strength and modulus, 22.2 and 711.6 MPa, respectively. The general trend of the composite results exhibited some decrease in water absorption and water loss from untreated RHF composites with only MAPE modification as compared to the NaOH-treated composite, although a rougher surface for the treated fibres was revealed in SEM images.

Effects of interface modification with self-assembled monolayers on the photovoltaic performance of CdS quantum dots sensitized solar cells

We employ 3-PPA, BPA and APPA as self-assembled monolayers (SAMs), who owns the same phosphonic acid headgroup but different tail group, to modify the surface of ZnO nanorods. Their effects on the photovoltaic performance of quantum dots sensitized soar cells are systematically investigated. The results indicate that the deposition of SAMs not only passivates the surface defects of ZnO nanorods, but also tunes their surface work function to adjust the band alignment of solar cells. In particular, the 3-PPA modification exhibits the best passivation effect and makes the surface work function of ZnO decreases by 1.04eV to realize a better band alignment due to its electron-withdrawing tailgroup, which results in an enhancement in photovoltaic conversion efficiency of solar cells.

Tuning the light response of organic field-effect transistors using fluorographene nanosheets as an interface modification layer

High-performance organic phototransistors (OPTs) have been successfully constructed using bitriisopropylsilylethynyl tetraceno[2,3-b]thiophenes (TIPSEthiotet) or pentacene as a semiconductor layer. Fluorographene (FG) nanosheets were used to modify the interface between an organic semiconductor layer and gate dielectric. The effects of interface modification were investigated. It was found that enhanced photoresponsivity and a boosted photocurrent/dark-current ratio could be easily achieved after the implantation of modification layers. The constructed FG-modified devices based on TIPSEthiotet showed a maximum photoresponsivity of 21.83 A W−1 and a photocurrent/dark-current ratio of 1.85 × 106 under white light irradiation. Meanwhile, for the FG-modified OPT device based on pentacene, a high photoresponsivity of 144 A W−1 was obtained under white light irradiation with an optical power of as low as 25 μW cm−2. This photoresponsivity datum is higher than that of most OPTs based on pentacene reported under the same conditions. In addition, the mobilities of the devices could also be increased distinctly after the introduction of the FG-modified layer. The experimental facts indicate that the strong electron trapping ability of the fluorine atoms in the FG nanosheets and the well-known photovoltaic effect play an important role in these interesting results.

Effects of Fibre Loading and Interfacial Modification on Physical Properties of Rice Husk/PE Composites

In this study, the physical properties of thermoplastic composites manufactured from linear medium density polyethylene (LMDPE), rice husk (RH) and maleic anhydride polyethylene (MAPE) were evaluated. Composites were manufactured with RH loadings of 15 wt%, 30 wt% and 50 wt% with 1 wt% of MAPE to investigate the effect of RH loading on the physical properties (water absorption and thickness swelling) of the composites. The results show that the water absorption and the corresponding thickness swelling increased with an increase in RH loading. Further manufacturing was carried out with 50 wt% of RH and 1wt%, 3.5 wt% and 6 wt% of MAPE to evaluate the effects of interfacial modification on the physical properties of the composites. The results show that the composites with 3.5 wt% of MAPE had least water absorption and the corresponding thickness swelling, whereas the composites having 1 wt% of MAPE had maximum water absorption and the thickness swelling. It can be concluded from these experiments that fibre loading as well as interfacial modification play a significant role in determining the physical properties of the composites.

Effect of interface modification on PMMA/graphene nanocomposites

Graphene platelets (GnPs) were surface modified with a long-chain surfactant B200, and then compounded with polymethyl methacrylate (PMMA). B200 provided an anchor into GnPs and a bridge into the matrix, thus creating molecular entanglement between matrix and GnPs. The interface modification promoted the dispersion of GnPs, as no aggregates of GnPs were observed on the fracture surface of the modified composites, in sharp contrast with the unmodified composites. Although GnPs formed clusters in the matrix, bilayer graphene was readily observed under TEM in randomly selected regions; it showed high structural integrity under diffraction pattern. The addition of 2.7 vol% m-GnPs produced 32.8 % improvement in the flexural modulus of PMMA as compared to 9.0 % by unmodified GnPs. At 1.1 vol%, the interface-modified composite showed a 19.6 % improvement in the absorption resistance to ethanol, in comparison with 3.8 % for the unmodified composites. The addition of 2.7 vol% m-GnPs improved fracture toughness of PMMA by 79.2 %, while GnPs enhanced it by 23.9 %.

Effect of interface modification on mechanical and thermal properties of high-density polyethylene/silvergrass composites

This study is aimed at utilizing the gramineae to reinforced polyethylene (PE). The interface modification was performed by treatment of silvergrass (SV) fibers with sodium hydroxide (NaOH) and polymeric methylene diphenyldiisocyanate (PMDI). The modified fibers were characterized by Fourier transform infrared spectroscopy. Composites were fabricated with different fiber loadings (10%, 20%, 30%, 40%, 50%, and 60%) of SV fibers by injection molding. The properties of the composites were studied by mechanical property, thermogravimetric analysis, and differential scanning calorimetry. The mechanical properties of the treated composites were compared well with those of untreated composites. A marked improvement of 49.0% in tensile strength and 47.35% in flexural strength for 40% SV fibers-reinforced high-density PE composites was noticed. It is also found that the treated fiber is acting as a nucleating agent. It can be deduced that the thermal stability of the wood–plastic composites can be improved when SV fibers were treated by NaOH and PMDI.

Effect of interface modifications on voltage fade in 0.5Li2MnO3·0.5LiNi0.375Mn0.375Co0.25O2 cathode materials

The effects of the coatings Al2O3, LiAlOx, ZrO2, TiO2, AlPO4, and LiPON and of the electrolyte additives 3-hexylthiophene and lithium difluoro (oxalato)borate (LiDFOB) on the voltage fade phenomenon in 0.5Li2MnO3·0.5LiNi0.375Mn0.375Co0.25O2 cathodes were investigated. Cells containing these materials or additives were cycled according to a standard protocol at room temperature between 2.0 and 4.7 V vs. Li+/Li. As expected, the cells containing either an additive or a coated cathode displayed less capacity loss than cells containing an uncoated cathode and no additive. The voltage fade phenomenon was quantified in terms of changes in the average cell voltage (Wh/Ah). The results indicate that, within experimental error, all of the coatings and additives produced little-to-no effect on voltage fade.

The Interface Modification of Low-Voltage Pentacene-Based Organic Phototransistors

Low-voltage organic phototransistors (OPTs) are promising for flexible optoelectronic applications such as photosensors and memories. In this paper, the effects of interface modification on the pentacene-based OPT are investigated. Commonly used polymer materials, polymethyl methacrylate, with different thicknesses are adopted on the high transparency and high permittivity tantalum pentaoxide (Ta2O5) gate dielectric layer. It is found that the thickness of the modifier layer can successfully tune the photosensitive characteristics of the low-voltage OPT. Through analysis of the energy level, the mechanism of the tuning is proposed that the polymeric layer acts as a tunneling layer for high-energy electrons and a blocking layer for low-energy electrons. Our study verifies that interface modification benefits not only the improvement of OPT performance but also the control of its applications in different fields.

Effects of interface modification by H2O2 treatment on the electrical properties of n-type ZnO/p-type Si diodes

The fabrication and detailed electrical properties of heterojunction diodes based on n-type ZnO and p-type Si were reported. The effect of interface modification by H2O2 treatment on the electrical properties of n-type ZnO/p-type Si diodes was investigated. The n-type ZnO/p-type Si diode without H2O2 treatment showed a poor rectifying behavior with an ideality factor (n) of 2.5 and high leakage, indicating that the interfacial ZnSixOy layer influenced the electronic conduction through the device. However, the n-type ZnO/p-type Si diode with H2O2 treatment showed a good rectifying behavior with n of 1.3 and low leakage. This is because the thin SiOx layer acts as a thermodynamically stable buffer layer to suppress interfacial reaction between ZnO and Si. In addition, the enhanced photo-responsivity can be interpreted by the device rectifying performance and interface passivation.