Organic Interfacial Layer Research Articles

Frequency-dependent capacitance and conductance characteristics and current transport mechanisms of Schottky diodes with TPA-IFA organic interfacial layer

In this study, a Schottky barrier diode with an Al/TPA-IFA/p-Si structure was fabricated using spin coating and thermal evaporation methods. Using forward and reverse bias I–V measurement, we examined the key electrical characteristics of the Al/TPA-IFA/p-Si diode, including Φb, n, Rs, and Nss; we also estimated VD, NA, EF, ∆Φb, WD, Φb and Nss using C–V measurements under the different frequencies (10, 50, 100, 500 kHz, and 1 MHz) at room temperature. Using I–V data and the Thermionic Emission (TE) theory, basic electrical parameters such as ideality factor ( n ), and barrier height ( Φb ) values were computed as 3.01 and 0.716 eV. The fundamental diode parameters are highly frequency-dependent. It was also found that the series Resistance ( Rs ) values reduced with increasing frequency, but the barrier height ( Φb ) and the width of the depletion layer ( WD ) increased. It was found that when frequency increased, the diode capacitance reduced for our new Schottky-type diode. The diode’s potential conduction mechanisms were examined through the utilization of reverse lnI−V0.5 and forward lnI−V graphs. The transport properties of Al/TPA-IFA/p-Si diode are primarily governed by ohmic conduction, Space Charge Limited Current (SCLC), and Trap Charge Limited Current (TCLC) mechanisms at low, moderate, and high voltages, respectively. It was concluded that the Poole–Frenkel Emission (PFE) mechanism was dominant for the Al/TPA-IFA/p-Si diode. Ultimately, the findings confirmed that the TPA-IFA-based diode could be obtained for the electronic application.

Investigation of illumination-dependent electrical and photodiode properties and conduction mechanism of the Al/p-Si contact with Schiff base compound (Pyr-Pic) interlayer

In this paper, an organic semiconductor, N-(2-((pyren-4-yl)methyleneamino)ethyl)-5- nitropyridin-2-amine (Pyr-Pic), was synthesized and was used as an interfacial organic layer to fabrication of Al/Pyr-Pic/p-Si/Al diode. The device’s characteristic parameters were determined under various operating situations using current–voltage (I-V) measurements. Thermionic emission theory (TE), the Cheung methodology, and Norde functions were the three methods used to determine the device’s electrical properties, such as the ideality factor, barrier height, and series resistance. Based on the I-V measurements conducted under illumination circumstances, the fabricated device exhibits photoresponse properties in the reverse bias region. An examination of the forward log(I)-log(V) plot of the Al/Pyr-Pic/p-Si diode indicated that ohmic conduction dominates carrier transport in the lower bias regions, while the space-charge-limited current (SCLC) governs transport in the medium bias regions, and the trap-charge limit current (TCLC) mechanism is responsible for transport in the higher bias regions. The current voltage mechanisms in the reverse bias area can be characterized by using Poole–Frenkel emission (PFE) and Schottky emission (SE) theories. The device exhibits photovoltaic characteristics when it is illuminated through an Al electrode. The typical photovoltaic parameters were estimated at room temperature and under illumination conditions.

Dendrite‐free Zn deposition initiated by nanoscale inorganic–organic coating‐modified 3D host for stable Zn‐ion battery

AbstractA 3D nanostructured scaffold as the host for zinc enables effective inhibition of anodic dendrite growth. However, the increased electrode/electrolyte interface area provided by using 3D matrices exacerbates the passivation and localized corrosion of the Zn anode, ultimately bringing about the degradation of the electrochemical performance. Herein, a nanoscale coating of inorganic–organic hybrid (α‐In2Se3‐Nafion) onto a flexible carbon nanotubes (CNTs) framework (ISNF@CNTs) is designed as a Zn plating/stripping scaffold to ensure uniform Zn nucleation, thus achieving a dendrite‐free and durable Zn anode. The introduced inorganic–organic interfacial layer is dense and sturdy, which hinders the direct exposure of deposited Zn to electrolytes and mitigates the side reactions. Meanwhile, the zincophilic nature of ISNF can largely reduce the nucleation energy barrier and promote the ion‐diffusion transportation. Consequently, the ISNF@CNTs@Zn electrode exhibits a low‐voltage hysteresis and a superior cycling life (over 1500 h), with dendrite‐free Zn‐plating behaviors in a typical symmetrical cell test. Additionally, the superior feature of ISNF@CNTs@Zn anode is further demonstrated by Zn‐MnO2 cells in both coin and flexible quasi‐solid‐state configurations. This work puts forward an inspired remedy for advanced Zn‐ion batteries.

A novel organic interface layer material to improve the efficiency of solar cells

Compared with the mature inorganic silicon solar cells[1] and perovskite solar cells[2], OSC is slightly obviously immature in terms of short service life and bad power conversion efficiency (PCE)[3]. Therefore, how to improve its durability and PCE to promote its development has become the main research direction. For solar cells, one of the most effective methods to improve their performance is to introduce different materials to optimize the electron transport layer to improve the charge transport characteristics inside the cell[4]. For organic solar cells, it is to modify the existing materials, introducing organic[5] (e.g. conductive polymer or polyelectrolyte) and inorganic[6][7][8] (e.g. metal oxide) interface modification layers to optimize this layer, so as to realize the regulation of interface energy level and improve PCE.In this work, the method of introducing an organic interface modified layer and reasonable experimental steps is used to synthesize non-conjugated polymer polyimide derivatives (BDI-RO). Combined with various photoelectric test methods and according to the work function and optical band gap of the modified interface layer, the effect of using BDI-RO as a cathode interlayer on the performance of OSC is studied and discussed.

Silicon distyryl-BODIPY hybrid photodiode: moving a step ahead from organic interface layer to type II band alignment

Organic-inorganic heterojunctions are becoming an attractive topic of research for their applications in hybrid photodetectors, solar cells, resistive switching memory devices etc. The easy chemical synthesis and low-cost fabrication for organic thin films come with the benefit of high light absorptivity, high fluorescence quantum yield and band gap tunability along with high charge carrier lifetime that could be combined with the existing silicon-based technology. In this aspect, various organic dyes utilised as an interfacial layer with silicon Schottky junction are reported earlier. However, the photo responses are quite limited. Here, in this report, a Type II Silicon/Distyryl-BODIPY p-n junction has been proposed as an organic-inorganic hybrid photodetector which has not been explored extensively yet. The transformation from a mere organic interfacial layer to band aligned junction enhances the charge carrier separation providing higher photo-responsive behaviour. With the simple spin-coating technique, the Distyryl-BODIPY derivative with phenolic functionalities is coated to fabricate the p-n junction diode. To further improve the performance, pyramidal surface texturization on silicon is deployed using wet chemical etching that supplements the light absorption with internal reflections. Both the devices have been investigated for their photo-response characteristic where a high photo-responsivity of 4353 A W−1 is attained for the textured device as compared to 118 A W−1 for the planar silicon device at a − 3 V bias with an ultra-high specific detectivity of 1012 Jones and 1010 Jones respectively. The behaviours of interfacial states have been demonstrated using the capacitance (C), conductance (G) and series resistance (RS) vs voltage (V) curves at different frequencies. Further calculations of interfacial state density revealed the existence of 1000 times higher interfacial states in planar device leading to lower performance as compared to pyramidal device. The findings in this report suggest that dye-based organic-inorganic heterostructures find potential applications in photodetectors and other optoelectronic devices.

Characterization of the electrical properties of MPS schottky structures incorporating Fe doped polyvinyl chloride (PVC)

This paper explores the effects of the organic interfacial layer on the electrophysical characteristics of Schottky barrier diodes (SBDs). Three types of SBDs were fabricated: Au-Si (referred to as MS), Au/PVC/Si (referred to as MPS1), and Au-/PVC:Fe/Si (referred to as MPS2). Fe nanopowders were subjected to analysis using XRD, SEM, and EDX techniques to investigate their structural and optical characteristics. To investigate the conduction mechanisms of these diodes, I-V characteristics were examined using thermionic-emission (TE), Cheung, and Norde functions. The surface-state density (N ss ) distribution of energy was determined by analyzing the current–voltage (IF-VF) curve under forward bias conditions. This analysis considered the voltage-dependent barrier height (BH) and ideality factor (n(V)). The results demonstrated that the polymeric interlayer without Fe nanoparticles reduced N ss by a factor of 7, while the presence of Fe nanoparticles led to a two-order magnitude decrease, resulting in improved efficiency in comparison with MS structures. The obtained results indicated that including a polymeric layer in MPS structure enhanced their electrophysical features compared to MS diodes, and significantly increased rectification by 15–45 times. In summary, the existence of an organic interfacial layer significantly altered the conduction mechanisms and electrophysical characteristics of MPS diodes. It was found that the addition of Fe nanoparticles in the interlayer resulted in substantial improvements in N ss , efficiency, rectification, and conduction characteristics compared to MS diodes.

Structural and electronic characterization of silicon based MIS contact by xanthene dye molecules (Erythrosine B)

The effect of erythrosine B (ERY) organic material as an interface layer on the electronic characteristics of the Al/p-Si junction is examined in the present work. AFM, NMR, UV–Vis and FTIR measurements have been conducted on the ERY dye molecule. The ERY film on the surface of the substrate is coated with nanoparticles, according to the surface analysis performed using the AFM technique. The basic diode parameters of Al/p-Si and Al/ERY/p-Si junctions were measured by utilizing current-voltage (I–V) and capacitance-voltage (C-V) techniques. The junctions with and without organic interfacial layers were found to have ideality factors of 1.931 and 1.925, respectively. For MS and MIS contacts, the estimated values of barrier height were 0.592 eV and 0.937 eV, respectively. Additionally, the series resistances for the MS and MIS structures by utilizing Norde function, were determined to be 0.14 kΩ and 322.85 kΩ, respectively. In addition, the reverse bias 1/C2-V characteristics were used to analyze the barrier height values and compare the findings to those from I-V method. The experimental findings demonstrated that the Al/ERY/p-Si MIS diode has a barrier height that is remarkably greater than that of the reference Al/p-Si junction. Placement of the ERY dye interlayer between a metal and a semiconductor could enhance and regulate the performance and characteristic of these types of junctions.

Spectroscopic analysis and device application of molecular organic dye layer in the Al/p-Si MIS contacts

In this paper, the effect of 1-phenylazo-2-naphthol (1PA2N) dye molecules used as an organic interfacial layer on the electronic features of Al/p-Si contact was investigated. An Al/1PA2N/p-Si junction was fabricated using the spin coating method. The 1PA2N dye molecule was investigated using nuclear magnetic resonance, Fourier transform infrared, ultraviolet–visible (UV–vis) spectroscopy, and atomic force microscopy (AFM) analyses. The 1PA2N dye in methanol had optical direct band energy values of 2.33 eV (Q band) and 3.70 eV (B band) according to UV–vis absorption measurements. Surface analysis using AFM indicated that the 1PA2N film on the substrate was covered in nanoparticles. Also, several junction parameters of the Al/1PA2N/p-Si structure were determined utilizing current–voltage measurements based on the thermionic emission mechanism. Moreover, the interfacial state density for the Al/1PA2N/p-Si structure ranged within 1.516 × 1013 to 1.880 × 1012 eV−1 cm−2 in darkness and 1.699 × 1013 to 1.823 × 1012 eV−1 cm−2 under light.

An Advanced Alkaline Al-Air Fuel Cell Using l-Ascorbic Acid Interface Layer upon Al Anode via Gradient Anti-corrosion

Al metal is considered as an excellent anode material for metal-air fuel cells thanks to the advantages in terms of capacity and energy density. However, the anodic parasitic corrosion has brought great obstacles to the performance breakthrough of Al-air fuel cells. Herein, we innovatively develop an advanced organic interface layer on an Al anode via gradient anti-corrosion, wherein low-cost, nontoxic, and high-ionized l-ascorbic acid is used to modify two basic research systems, 4 M KOH and 4 M KOH electrolyte containing 0.3 M ZnO. The results show that the relative anti-corrosion efficiency of Al and Zn@Al anodes can be gradually enhanced with the increase of l-ascorbic acid concentration. The optimal modification concentration of l-ascorbic acid is 0.35 M. The capacity and anode utilization of the cell increase to 479.50 mAh/g and 16.09% at 20 mA/cm2 after the l-ascorbic acid modification of 4 M KOH, respectively, while an excellent capacity of 2208.39 mAh/g and an anode utilization of 74.09% can be achieved for the cell using an l-ascorbic acid interface layer on a Zn@Al anode at the same current density. The density functional theory reveals that the groups of O–C═C–O and C═O in the layer molecules tend to accept the electrons provided by the Al and Zn@Al surfaces and release more adsorption energy than free H2O. l-ascorbic acid molecules are adsorbed on the anode surface as a stable interface layer, achieving Al self-corrosion inhibition and promoting the sustainable development of Al-air fuel cells.

The light detection performance of the congo red dye in a Schottky type photodiode

The Congo red (CR) (3,3′-[(1,1′,-biphenyl)-4,4′-diyl)bis(4-amino-1 amino naphthalene sulphonic)]) is usually used for staining of amyloidosis diseases in the diagnostic application. It shows dichroic behavior, and thus can be employed in optoelectronic applications. In this study, commercially purchased congo red dye was used as an interfacial organic layer for Schottky type photodiode to understand its sensitivity to light. The surface morphology of the CR interlayer was investigated by scanning electron microscopy (SEM), and almost uniform surface was obtained. While cobalt (Co) element was employed as metallic contact, the n-type Si and aluminum (Al) were used as a semiconductor and ohmic contact, respectively. Thus, Co/CR/n-Si device was fabricated by a spin coating and thermal evaporation technique, and characterized by I-V measurements under dark and various light power intensities. The results revealed that the congo red dye can be improved and employed for optoelectronic applications.

Graphene/Si Heterostructure with an Organic Interfacial Layer for a Self-Powered Photodetector with a High ON/OFF Ratio

Graphene/Si Heterostructure with an Organic Interfacial Layer for a Self-Powered Photodetector with a High ON/OFF Ratio

Improving the performance of QSEDLCs by modulating the properties of electrolytes from bulk to interfaces.

A strategy through the combination of a polyzwitterion matrix, salt mixture, and interfacial organic solvent layer is proposed to achieve an improvement in the performance of gel polymer electrolyte-based quasi-solid-state electrical double-layer capacitors by modulating the properties of the electrolytes from bulk to interfaces.

Optical and Electrical Properties of Pyrene–Imine Organic Interface Layer Based on p-Si

Optical and Electrical Properties of Pyrene–Imine Organic Interface Layer Based on p-Si

Investigation of electrical and photovoltaic properties of Au/n-Si Schottky diode with BOD-Z-EN interlayer

4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) based BOD-Z-EN compound was used as an interfacial organic layer to fabrication of Au/BOD-Z-EN/n-Si/In diode. The electrical parameters of Au/BOD-Z-EN/n-Si/In diode such as ideality factor (n), barrier height (Φb) and series resistance (Rs) have been investigated through current–voltage (I–V) studies at dark and under various illumination intensities to understand the effect of interlayer on the device properties. The values found for the n varied from 2.33 to 1.55 and the Φb ranged from 0.86 to 0.90 eV as the illumination condition changed from dark to 100 mW/cm2. Series resistance (Rs) values calculated using Cheung’s method were found to decrease with increasing illumination level. The forward bias I–V characteristics of the diode were explained by the space charge limited current theory. The main photovoltaic parameters such as open circuit voltage (Voc), short circuit current density (Jsc) and fill factor (FF) were determined for various light intensity. The Au/BOD-Z-EN/n-Si/In diode exhibits a photovoltaic behavior with a Voc of 150 mV and Jsc of 10 µA/cm2 under 100 mw/cm2. In addition, photosensitivity and photoresponsivity properties of the diode were determined. All these results indicate that Au/BOD-Z-EN/n-Si/In device can be used as photosensor in optoelectronic applications.

Multi-dimensional interfacial engineering for a practical large-area transparent flexible organic photovoltaics

Although the efficiency improvement by the research of interlayer and photo-active layer in the field of organic photovoltaics has been achieved, the practical research for commercialization to be applied in a large area, flexible and transparent module is still rare and lagging behind. Herein, we present a flexible and semitransparent large area photovoltaic with a high-performance by engineering the charge transport with a molecular linker as an organic interfacial layer. The insertion of a molecular linker between the electron transporting layer and the organic active layer led to a considerable increase in power conversion efficiency as well as an improvement in stability and flexibility. We also compared the device performance after 100 days, there is an 80% decrease in photovoltaic efficiency. However, after the inclusion of the molecular linker, there is only a 10% decrease. The molecular linker can bond well the electron transporting layer and photo-active layer to improve mechanical durability. We also tested with various photo-active layer conditions (thickness) and module types (area and number of cells). After charge transport engineering, we obtained improved results for all conditions. Finally, with this charge transport engineering, we obtained a remarkably high figure of merit for transparent flexible organic photovoltaic mini-modules which has 41.45% transmittance with an efficiency of 8.22% for sub-(50 mm × 70 mm) and 6.43% for sub-(100 mm × 100 mm) modules. This FOM is higher than the reported studies. For application we made a convergence module (100 mm × 100 mm) which composed electrochromic and photovoltaic. As a result, there is a self-powered EC-PV convergence module well-operated under the light. It could potentially be applied to smart window systems.

Enhanced flexible optoelectronic devices by controlling the wettability of an organic bifacial interlayer

Solution-processed flexible organic optoelectronic devices have great potential as low-cost organic photovoltaics for energy harvesting, and in organic light-emitting diodes as a lighting source. However, a major challenge for improving device performance and stability is the different interfacial characteristics of the hydrophobic organic layers and hydrophilic transparent electrodes, particularly for flexible devices. Surface wetting controlled interfacial engineering can provide a useful method to develop highly efficient flexible organic devices. Here, an unsaturated fatty acid-modified ethoxylated polyethyleneimine organic interfacial layer is designed, which is hydrophobic or hydrophilic on different interfaces. This interlayer results in a power conversion efficiency of 10.57% for rigid and 9.04% for flexible photovoltaic devices. Furthermore, the long-term air storage stability for 250 h is substantially improved, retaining 87.75% efficiency without encapsulation, due to the wettability driven improvement of the optical and electronic properties of the cathode interfacial layer. The performance of organic light emitting diodes also benefitted from the interlayer. This study provides a strategy to simultaneously improve efficiency and stability by controlling the wettability of the interfacial layer.

The investigation of the fundamental electrical parameters of Ag/n-Si hybrid structure based on functional organic dye

The electrical parameters of Ag/n-Si contact and the hybrid structure has been investigated due to their possible usage in optoelectronic device applications. In this study, the hybrid structure was fabricated using the brilliant blue film as an organic interlayer formed via spin coating method. The electrical parameters of both devices have been determined and compared using the current-voltage (I-V) and capacitance-voltage (C-V) measurements at room temperature. The experimental results confirmed that the barrier height of hybrid structure is considerably affected; and its performance and quality can be modified/controlled by the functional interfacial organic layer.

Complex dielectric, complex electric modulus, and electrical conductivity in Al/(Graphene-PVA)/p-Si (metal-polymer-semiconductor) structures

In this study, the real and imaginary components of the complex dielectric (ε* = ε′ - jε'′), complex electric modulus (M* = M′ + jM'′), and electrical conductivity (σac) were investigated for fabricated Al/(5% graphene (Gr)-PVA)/p-Si (metal-polymer-semiconductor (MPS)) type structures in wide frequency (5 kHz–5 MHz) and voltage (±4 V) ranges by using impedance (Y = 1/Z = G + jωC) measurements. To determine more charges/energy in a capacitor, a high dielectric (5% Gr-PVA) organic interface layer was used for growth by using the electrospinning method. We observed that the capacitance of the MPS was increased considerably by using this interlayer. As the frequency increased from 5 kHz to 5 MHz, the ε′ values changed from 32.586 to 1.132 due to the presence of surface/dipole polarization and the number of surface states (Nss). The lower M′ values observed at low frequencies were related to the long-range mobility of charge carriers. The magnitudes and positions of the peaks observed in the tanδ-V and M″-V plots varied with the frequency. Furthermore, the observed magnitudes and positions of the peaks in the tanδ-V and M″-V plots changed with the frequency. Thus, we showed that a (5% Gr-PVA) organic interlayer should be preferred to an insulator obtained with the traditional method because of its flexibility, low energy consumption, and simple grown process.

Gaining Insight into the Effect of Organic Interface Layer on Suppressing Ion Migration Induced Interfacial Degradation in Perovskite Solar Cells

AbstractIon migration induced interfacial degradation is a detrimental factor for the stability of perovskite solar cells (PSCs) and hence requires special attention to address this issue for the development of efficient PSCs with improved stability. Here, an “S‐shaped, hook‐like” organic small molecule, naphthalene diimide derivative (NDI‐BN), is employed as a cathode interface layer (CIL) to tailor the [6,6]‐phenylC61‐butyric acid methylester (PCBM)/Ag interface in inverted PSCs. By realizing enhanced electron extraction capability via the incorporation of NDI‐BN, a peak power conversion efficiency of 21.32% is achieved. Capacitance–voltage measurements and X‐ray photoelectron spectroscopy analysis confirmed an obvious role of this new organic CIL in successfully blocking ionic diffusion pathways toward the Ag cathode, thereby preventing interfacial degradation and improving device stability. The molecular packing motif of NDI‐BN further unveils its densely packed structure with π–π stacking force which has the ability to effectually hinder ion migration. Furthermore, theoretical calculations reveal that intercalation of decomposed perovskite species into the NDI clusters is considerably more difficult compared with the PCBM counterparts. This substantial contrast between NDI‐BN and PCBM molecules in terms of their structures and packing fashion determines the different tendencies of ion migration and unveils the superior potential of NDI‐BN in curtailing interfacial degradation.

Engineering anisotropic magnetoresistance of Hall bars with interfacial organic layers

Tuning the magnetoresistance behavior of heterostructures composed of nonmagnetic and ferromagnetic (FM) materials is crucial for improving their applicability in electronic and spintronic devices. In this study, we investigate whether the integration of organic layers to NiFe/Pt junctions can result in the modification of the magnetic moment of the FM layer using iron phthalocyanines (FePc) and copper phthalocyanines (CuPc) as the interfacial layers for controlling the spin-charge conversion. Relaxation of the out-of-plane magnetic hard axis of the NiFe/Pt junctions is observed, as a result of the modification of the interfacial magnetic structure. The transport measurements of the fabricated hybrid Hall bar junctions with NiFe/FePc/Pt and NiFe/CuPc/Pt reveal that although the intrinsic anisotropic magnetoresistance of the present Hall bar is maintained with the integration of interfacial metal phthalocyanine (MPc) layers, a change in the magnetic response along the axis perpendicular to the in-plane of Hall bars is observed, owing to the insertion of the interfacial MPc layers. The present method of interface engineering via integration of organic interfacial layers can act as a model system for controlling the spin-charge conversion behavior of magnetic heterojunction toward the development of multifunctional molecular-engineered spintronic devices.