Hybrid Heterojunction Research Articles

Amorphous Silicon Particles/Polyaniline Composites for Hybrid Photovoltaic Solar Cell: an Experimental Feasibility Study

Hybrid heterojunctions of Polyaniline/Amorphous Silicon (PAni / a-Si:H) were synthesized in order to fabricate the active layer of the polymeric solar cells. For this purpose, amorphous silicon nanoparticles were blended with polyaniline which was synthesized through oxidative polymerization. Then the resultant nanocomposite was applied on FTO in the FTO/ZnO/PANI:a-Si/Ag structure using the spin coating method. The effect of amorphous silicon content on light-harvesting efficiency was studied using the UV-VIS spectroscopy data, electrochemical impedance spectroscopy (EIS), and the incident photon to current efficiency (IPCE) analysis. PAni / a-Si:H nanocomposites were characterized structurally and morphologically using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD) analysis. Current-Voltage measurements of the photovoltaic cells based on PAni / a-Si:H nanocomposites show that increasing the amount of a-Si:H in the active layer up to 40%Wt, the efficiency of the cell increases 2k times compared to the cell made with pure PAni. Also, in general, cell efficiencies increase slightly with decreasing the size of amorphous silicon nanoparticles at a constant PAni / a-Si:H weight ratio. The impact of a-Si:H weight percent is more significant in the case of smaller silicon particles.

Hybrid PEDOT:PSS/SiC heterojunction UV photodetector with superior self-powered responsivity over A/W level

In this Letter, an ultraviolet photodetector constructed on a simple vertical PEDOT:PSS/SiC hybrid heterojunction with superior self-powered performance was reported. Benefitting from the abundant charge carrier concentration in 4H-SiC substrate and the large built-in field at PEDOT:PSS/SiC heterointerface, the SiC based photodetector (PD) realized self-powered responsivity over A/W level, even comparable with many reported 4H-SiC avalanche photodiodes. Upon illumination with deep-UV wavelength at 254 nm, the responsivity, detectivity, and external quantum efficiency of the fabricated PD reached up to 2.15 A/W, 1.9 × 1013 Jones, and 1053%, respectively. Furthermore, the rise/decay time was as fast as 58.6/41.5 ms, the on–off switching ratio was as large as 8.73 × 103, the spectral rejection ratio (R254/R390) was as high as 4.3 × 103, and the lifetime reliability was over 195 days. Serving as a sensing pixel, the designed heterojunction PD demonstrated excellent imaging capability in homemade UV imaging system, showing promising applications in future energy-conservation photoelectronic system.

Engineering of a Hybrid g-C3N4/ZnO-W/Cox Heterojunction Photocatalyst for the Removal of Methylene Blue Dye

Robust hybrid g-C3N4/ZnO-W/Cox heterojunction composites were synthesized using graphitic carbon nitride (g-C3N4) and ZnO-W nanoparticles (NPs) and different concentrations of Co dopant. The hybrid heterojunction composites were prepared by simple and low-cost coprecipitation methods. The fabricated catalyst was explored and investigated using various characterization techniques such as FTIR, XRD, FESEM and EDX. The surface morphology of the as-prepared hybrid nanocomposites with particle sizes in the range of 15–16 nm was validated by SEM analysis. The elemental composition of the synthesized composites was confirmed by EDS analysis. Photocatalysis using a photon as the sole energy source is considered a challenging approach for organic transformations under ambient conditions. The photocatalytic activity of the heterojunctions was tested by photodegrading methylene blue (MB) dye in the presence of sunlight. The reduced band gap of the heterojunction composite of 3.22–2.28 eV revealed that the incorporation of metal ions played an imperative role in modulating the light absorption range for photocatalytic applications. The as-synthesized g-C3N4/ZnO-W/Co0.010 composite suppressed the charge recombination ability during the photocatalytic degradation of methylene blue (MB) dye. The ternary heterojunction C3N4/ZnO-W/Co0.010 composite showed an impressive photocatalytic performance with 90% degradation of MB under visible light within 90 min of irradiation, compared to the outcomes achieved with the other compositions. Lastly, the synthesized composites showed good recyclability and mechanical stability over five cycles, confirming them as promising photocatalyst options in the future.

Bifunctional S-scheme hybrid heterojunction comprising CdS nanorods and BiOIO3 nanosheets for efficient solar-induced antibiotic degradation and highly-selective CO2 reduction

The development of a bifunctional photocatalyst that can be utilized for both energy conversion and environmental remediation is of great practical significance. In addition, an S-scheme charge transfer process can assist a photocatalyst in efficiently separating photoexcited electrons and holes while maintaining the strong reducibility and oxidizability of the former and the latter, respectively. We developed a bifunctional S-scheme hybrid photocatalyst comprising CdS nanorods and BiOIO3 (BIO) nanosheets for efficient antibiotic degradation and cocatalyst- and sacrificial reagent-free CO2 reduction. The combination of visible-light-responsive one-dimensional (1D) CdS and UV-light-responsive 2D BIO resulted in a CdS/BIO hybrid photocatalyst with effective 1D/2D (line) interfacial contact and a broadened optical absorption range. Notably, the CdS/BIO hybrid exhibited exceptional diclofenac degradation and mineralization as well as outstanding CO2 reduction activity for CO production, with 95.4% CO selectivity over H2 production. The exceptional performance of the hybrid catalyst is primarily attributed to the accelerated photoexcited charge transfer caused by the 1D/2D line interfacial contact and the high charge separation and strong redox power of the separated charges, both of which stem from the effective S-scheme charge transfer process. In addition, photocorrosion of CdS was substantially mitigated, resulting in the high photocatalytic performance of the hybrid catalyst even after repeated test runs. This study provides insight into the rational design of bifunctional S-scheme hybrid photocatalysts for CO2 reduction and pollutant degradation.

Study on the Fabrication of PEDOT:PSS/Si Hybrid Solar Cells Incorporated with F4TCNQ and VTMO

Poly(3,4-ethylenedioxythiophene) (PEDOT):polystyrenesulfonate (PSS)/Si hybrid heterojunction solar cells (HHSCs) are fabricated by a solution-based synthesis method which combines the advantages of PEDOT:PSS and the superior performance of crystalline silicon. The optimized PEDOT:PSS–2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) hole transport layer (HTL) was used to prepare organosilicon solar cells with a short-circuit current density (Jsc) of 33.33 mA/cm2 and a photoelectric conversion efficiency (η) of 13.23%. The HTL films were found to have increased conductivity by the addition of an electron-accepting dopant (F4TCNQ), obtaining well-defined crystallinity and few defects. In addition, an one-step combination of F4TCNQ with a silane coupling agent (vinyltrimethoxysilane, VTMO) was used to improve the textured device, with a notable efficiency of 14.46% and a Jsc of 33.88 mA/cm2. Our study provides an alternative and easy way to establish organic–inorganic hybrid applications with excellent optoelectronic properties and to gain a deeper understanding of organic semiconductors.

Temperature dependent characteristics of flexible p-PANI/n-ZnO based hybrid heterojunction diode

This study aims to develop and characterize a flexible p-PANI/n-ZnO heterojunction diode developed from a combination of electrochemical and sputtering technique. Investigation of structural properties and morphology of the thin films has been done from XRD and SEM analysis. To study the temperature effect on the electrical properties of the diode, current–voltage–temperature (I–V–T) measurements were done for the temperature range 25–300 K. Applying the ideal thermionic emission theory, various diode parameters like reverse saturation current, quality factor, series resistance and barrier height were computed utilizing the semilogarithmic plot of I–V curve and Cheungs’ method. Barrier height, reverse saturation current and quality factor calculated from ln(I) versus V curve were observed to vary from 0.0627–0.725 eV, 0.236–98.8 nA and 54.43–3.29 respectively over the temperature range 25–300 K. It has been found that the series resistance falls with a rise in temperature. The barrier height, series resistance and ideality factor were observed to vary from 0.0628–0.692 eV, 15 900–46.8 Kohm and 41.88–2.27 respectively for the temperature range 25–300 K. The activation energy estimated from Arrhenius plot was observed to be 14.51 meV. Additionally, the fabricated PANI/ZnO diode was mechanically robust that can be bent without affecting its performance.

Nanoengineered lanthanum niobate nanocaviar anchored carbon nanofibers for trace level detection of menadione in environmental samples

An innovative sensor is prepared by electrode modification through a nano-ranged electrode modifier composed of LaNbO4 nano caviars decorated on the enmeshed carbon nanofibers to identify excess vitamins in animal feed. Menadione (Vitamins K3) is a micronutrient fundamentally required in precise quantities for animal health upkeep. Still, its exploitation has recently resulted in water reservoir contamination through waste generated from animal husbandry. Sustainable prevention of water contamination makes menadione detection highly imperative and flickered the attention of researchers. Considering these aspects, a novel menadione sensing platform is designed by interdisciplinary incorporation of nanoscience and electrochemical engineering. The structural and crystallographic features and the electrode modifier's morphological insights were keenly investigated. The hierarchal arrangement of individual constituents in nanocomposite is benefited through hybrid heterojunction and quantum confinement that synchronously activate the menadione detection with a LOD of 68.5 nM and 67.49 nM for oxidation and reduction, respectively. The as-prepared sensor has a wide linear range (0.1–173.6 μM), high sensitivity, good selectivity, and stability. The application of this sensor is extended to a water sample to monitor the consistency of the proposed sensor.

Facile Synthesis, Characterization, and Photocatalytic Performance of BiOF/BiFeO3 Hybrid Heterojunction for Benzylamine Coupling under Simulated Light Irradiation

Under simulated light irradiation, the aerobic oxidation of benzylamine to N,N-benzylidenebenzylamine was carried out as a model reaction to investigate the photocatalytic activity of a hydrothermally prepared composite based on BiOF and BiFeO3 materials. The prepared photocatalysts were characterized using several spectroscopic techniques, such as powder X-ray diffraction (PXRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR). Band gap analysis showed that the composite exhibits a band gap that lies in the UV region (3.5 eV). Nonetheless, pristine BiOF and BiFeO3 exhibited band gaps of 3.8 eV and 2.15 eV, respectively. N,N-benzylidenebenzylamine was selectively achieved with a high conversion yield of ~80% under atmospheric conditions in which the product was confirmed using 1H-NMR, 13C-NMR, and FTIR spectroscopic techniques. Various control experiments were conducted to further confirm the enhanced photocatalytic performance of the reported composite.

Hybrid 2D/3D Graphitic Carbon Nitride‐Based High‐Temperature Position‐Sensitive Detector

Ultraviolet position‐sensitive detectors (PSDs) are expected to undergo harsh environments, such as high temperatures, for a wide variety of applications in military, civilian, and aerospace. However, no report on relevant PSDs operating at high temperatures can be found up to now. Herein, we design a new 2D/3D graphitic carbon nitride (g‐C3N4)/gallium nitride (GaN) hybrid heterojunction to construct the ultraviolet high‐temperature‐resistant PSD. The g‐C3N4/GaN PSD exhibits a high position sensitivity of 355 mV mm−1, a rise/fall response time of 1.7/2.3 ms, and a nonlinearity of 0.5% at room temperature. The ultralow formation energy of −0.917 eV atom−1 has been obtained via the thermodynamic phase stability calculations, which endows g‐C3N4 with robust stability against heat. By merits of the strong built‐in electric field of the 2D/3D hybrid heterojunction and robust thermo‐stability of g‐C3N4, the g‐C3N4/GaN PSD delivers an excellent position sensitivity and angle detection nonlinearity of 315 mV mm−1 and 1.4%, respectively, with high repeatability at a high temperature up to 700 K, outperforming most of the other counterparts and even commercial silicon‐based devices. This work unveils the high‐temperature PSD, and pioneers a new path to constructing g‐C3N4‐based harsh‐environment‐tolerant optoelectronic devices.

Synergistic Effect of Hybrid CdSe Nanobelt/PbI2 Flake Heterojunction Toward Drastic Performance Flexible Photodetectors.

Despite numerous studies on broadband photodetectors, the problematic query that remains unaddressed is the limited photoresponsivity while broadening the spectral regime. Here, for the first time, a rational design of a hybrid 1D CdSe nanobelt/2D PbI2 flake heterojunction device is constructed, which substantially boosts the photocurrent while significantly attenuating the dark current, resulting in improved photodetector figures-of-merit. Thanks to the excellent quality of the nanobelt/flake and built-in electric field at the CdSe/PbI2 interface heterojunction, photogenerated carriers are promptly segregated and more photoexcitons are accumulated by the respective electrodes, enabling a high responsivity of ∼106 A/W, making this one of the highest values among similar reported hybrid heterojunction photodetectors, together with a large linear dynamic range, superior sensitivity, excellent detectivity and external quantum efficiency, an ultrafast response, and a broadband spectral response range. The similar 1D/2D hybrid heterojunction device architecture assembled on the flexible polyimide tape substrate exhibits excellent folding endurance and mechanical, flexural, and long-term environmental stability. The present device architecture and robust operational stability in an ambient environment reveals that the combination of the present 1D/2D hybrid heterojunction has incredible potential for future flexible photoelectronic devices.

Strong Photocurrent from Solution‐Processed Ruddlesden–Popper 2D Perovskite–MoS2 Hybrid Heterojunctions

AbstractThis study reports overall improvement in structural, morphological, and optoelectronic properties of Ruddlesden–Popper (RP) perovskites of type (BA)2(MA)n−1PbnI3n+1 by forming their bulk heterojunction hybrids with few‐layer MoS2 nanoflakes. RP perovskite–MoS2 hybrid thin films have shown significantly improved packing and crystallinity compared to pristine perovskites. The presence of MoS2 at RP perovskite interface has improved the quantum confinement effects and transport of photogenerated charge carriers from perovskite to MoS2, due to suitable conduction band of MoS2 and more number of decay channels. The optoelectronic properties of RP perovskite–MoS2 hybrids are studied for various MoS2 concentrations (4.2–25.6 × 10−3 m) and at optimum concentration (12.8 × 10−3 m) the photodetectors (n = 2, 4) have shown strong, sharp, and highly stable photocurrent response. At 0.0 V bias, the RP perovskite (n = 4) and MoS2 (12.8 × 10−3 m) hybrid‐based photodetectors, prepared without any encapsulation, have shown strong photocurrent density of ≈9.8 µA cm−2 under 1 sun illumination, which is ≈17 times higher compared to the pristine RP perovskites‐based photodetector (0.6 µA cm−2). Further transient photocurrent, performed over 200 cycles for hybrid (n = 4+MoS2) thin film photodetector under laser (λex ≈ 405 nm, ≈630 mW cm−2) illumination and ambient air conditions has shown highly stable photocurrent with only ≈9.6% reduction in the peak photocurrent density.

Achieving low contact resistivity in PEDOT:PSS/n-Si solar cells

Good conductivity and transparency in the visible spectrum along with low processing temperatures and ease of fabrication make Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) a widely accepted polymer for organic-inorganic hybrid heterojunction solar cells. Although the overall conductivity of the PEDOT:PSS is high, the PSS segregates more at the surfaces of the deposited film. This leads to high contact resistivity of PEDOT:PSS film with metal and silicon. In this report, we explore the effect of the spin coating rates on the contact resistivity of PEDOT:PSS with the metal and silicon and the associated performance of PEDOT:PSS/n-Si solar cells. Two different spin speeds of 1000 rpm and 4000 rpm were used to deposit the PEDOT:PSS films over silicon. The PEDOT:PSS films were also deposited in single- and double-layer forms. We could achieve very low contact resistivity of PEDOT:PSS with silicon through spin speed optimizations. Hence, the overall performance of the PEDOT:PSS/n-Si solar cells improves with the spin speed for both single- and double-layer PEDOT:PSS film depositions.

Mediation of Interface Dipoles on SiOx/Si Nanowire Based Inorganic/Organic Hybrid Photodetectors with Enhanced Wavelength‐Selective Sensing Performances

AbstractThe promising hybrid photodetector design is realized through the incorporation of PEDOT:PSS layer with SiOx/Si nanowires (SiNWs), which went beyond the intrinsic limitation of band‐gap associated photosensing characteristics of conventional Si semiconductors toward revolutionarily turning into wavelength‐selective features. These can be interpreted by two determining effects. First, the effective trapping of incident lights with wavelength of 590 nm is evidenced on SiOx/SiNWs. Besides, the creation of interfacial potentials, arising from the positively charged PEDOT:PSS and negatively charged SiOx, manifested the reduction of electron density at PEDOT:PSS surfaces and in turn raised the work function. These features explicitly modulated the carrier‐transport characteristics at hybrid heterojunctions, which accounted for the suppression of photocurrents under light excitations with wavelengths of either 365 nm or 850 nm. The established photodetectors with optimal oxidation treatment resulted in the substantial improvement of both device responsivity and detectivity above 11 times beyond the PEDOT:PSS/SiNWs designs, which shed new light on practical applications of hybrid photodetectors.

Solution-Processed Organic–Inorganic Semiconductor Heterostructures for Advanced Hybrid Phototransistors

Organic/inorganic hybrid phototransistors are an emerging class of advanced optoelectronic devices. The separated organic high absorption layer and inorganic carrier transport layer endow hybrid phototransistors with remarkable sensing performance in a broad spectrum. The flexibility, ambient stability, and process compatibility of organic and metal oxide semiconductors also render them promising for large-area matrix integration and wearable applications. Moreover, extraordinary photoelectric behaviors, such as bidirectional photoresponses and the versatility of in-sensor computing functions, including feature extraction and image enhancement, can be obtained by rational customization of the hybrid heterojunctions. In this Spotlight on Applications, we review the recent progress of organic/inorganic hybrid phototransistors and their applications in photodetection, sensor arrays, flexible electronics, and in-sensor computing.

Rapid and facile synthesis of Z-scheme ZnO/g-C3N4 heterostructure as efficient visible light-driven photocatalysts for dye degradation and hydrogen evolution reaction

The coupling of two-different semiconductors which are photocatalytically active is gaining popularity in recent years because the heterojunction can decrease the rate of recombination of photoexcited electron-hole pairs and enhance the photocatalytic activity. In the current work, ZnO/g-C3N4 heterojunction hybrids have been generated by simple solution mixing of the dispersed ZnO and graphitic carbon nitride (g-C3N4) nanoparticles. The ZnO/g-C3N4 composite under visible light exhibits 91.5% degradation of the methylene blue (MB) dye in 120 min and also demonstrated excellent cyclic stability. Mechanistic studies and dye degradation experiments carried out in the presence of scavengers (ascorbic acid, potassium dichromate and ammonium oxalate) revealed that the generated superoxide radical (O2•‒) and hydroxyl radicals play a crucial role in MB dye degradation using ZnO/g-C3N4 as a photocatalyst. Further, the ZnO/g-C3N4 composite exhibits improved hydrogen evolution reaction (HER) activity (1358 μmol g-1 h-1) compared to the pristine ZnO nanoparticles (545 μmol g-1 h-1) and g-C3N4 (238 μmol g-1 h-1). The superior HER activity of the hybrid is ascribed to the increased charge-transfer rate owing to the better interfacial contact between the heterocomponents. Secondly, the nanoparticle nature of ZnO and g-C3N4 heterocomponents provides more exposed edge sites and thereby gives significant photocatalytic activity.

CdTe QD-decorated GO nanosheet heterojunction for efficient photocurrent generation and photocatalytic activity.

Cadmium telluride quantum dot (CdTe QD)-decorated graphene oxide (GO) nanosheets are promising heterojunctions for the environmental remediation of organic pollutants in water. However, assembling these two materials is a challenge. For this purpose, we have developed a one-step approach for the decoration of QDs onto the surface of GO nanosheets/intercalation of QDs into GO nanosheets through self-assembly, resulting in the formation of sandwiched hybrid heterojunctions. After synthesis, the samples were analysed for variations in their structural, morphological, compositional, optical and photoelectrochemical characteristics using various analytical tools. Interlinking QDs and GO nanosheets enhanced the photocurrent generation (∼5.8 μA cm-2), resulting in faster electron transfer by delaying the decay time (58.25 ms). A higher rate constant value (k = 0.135 min-1) was obtained for degrading 93% MB dye in 20 min. This work demonstrates a cost-effective strategy for constructing CdTe QDs/GO nanosheet hybrid heterojunctions for potential application in the field of photocatalysis.

High efficiency flexible PEDOT:PSS/silicon hybrid heterojunction solar cells by employing simple chemical approaches

Efficient flexible hybrid solar cells with basic device architecture are demonstrated using the low-cost Si wafers via simple chemical approaches, and may lead to the next-generation flexible optoelectronic applications with 4-fold reduced Si usage.

Immobilization of a TiO2-PEDOT:PSS hybrid heterojunction photocatalyst for degradation of organic effluents.

Heterojunction photocatalysts have recently emerged for use in degradation of organic pollutants, typically being suspended in effluent solution to degrade it. Post degradation, the catalyst must be removed from the treated solution, which consumes both energy and time. Moreover, the separation of nano catalysts from the treated solution is challenging. In the present work, we explore fabrication of immobilized TiO2-PEDOT:PSS hybrid heterojunction catalysts with the support of a PVA (polyvinyl alcohol) matrix. These photocatalytic films do not require any steps to separate the powdered catalyst from the treated water. While the PVA-based films are unstable in water, their stability could be significantly enhanced by heat treatment, enabling efficient removal of organic effluents like methylene blue (MB) and bisphenol-A (BPA) from the aqueous solution under simulated sunlight irradiation. Over 20 cycles, the heterojunction photocatalyst maintained high photocatalytic activity and showed excellent stability. Hence, an immobilization of the TiO2-PEDOT:PSS hybrid heterojunction is suggested to be beneficial from the viewpoint of reproducible and recyclable materials for simple and efficient wastewater treatment.

A pH-value sensitive and self-powered photodetector based on an anthocyanin/graphene heterojunction

An anthocyanin-graphene hybrid heterojunction has been designed as a highly pH-value sensitive and self-powered photodetector.

A conjugated polymer coupled with graphitic carbon nitride for boosting photocatalytic hydrogen generation under visible light

A polymeric heterojunction hybrid composed of a C6-FDTP conjugated polymer and graphitic carbon nitride via π–π interactions exhibits superior photocatalytic hydrogen generation under visible light irradiation.