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Front contact optimization for rear-junction SHJ solar cells with ultra-thin n-type nanocrystalline silicon oxide
摘要： In this work, ultra-thin n-type hydrogenated nanocrystalline silicon oxide [(nc-SiOx:H (n)] film was used to replace amorphous silicon [a-Si:H (n)] as electron transport layer (ETL) in rear-junction silicon heterojunction (SHJ) solar cell to reduce front parasitic absorption. The contact resistivity between the transparent conductive oxide (TCO) and ultra-thin ETL interface plays an important role on the cell performance. A nanocrystalline silicon (nc-Si:H) contact or seed layer was introduced in the solar cell with ultra-thin nc-SiOx:H and the impact of the nc-Si:H thickness on the cell performance was investigated. To demonstrate scalability, bifacial solar cells with 10 nm ETL were fabricated on the M2 (244 cm2) wafer. The best cell performance is obtained by the solar cell with 5 nm nc-SiOx:H (n) and 5 nm nc-Si:H (n) contact layer and it exhibits open-circuit voltage (Voc) of 738 mV, fill factor (FF) of 80.4%, short-circuit current density (Jsc) of 39.0 mA/cm2 and power conversion efficiency (η) of 23.1% on M2 wafer. Compared to the one with nc-SiOx:H (n), an increase of 3%abs of FF and 0.5%abs of η and lower front contact resistivity is demonstrated for the solar cells with nc-Si:H (n) / nc-SiOx:H (n) double layer, which is caused by the lower energy barrier for electrons, according to the band diagram calculated by the AFORS-HET simulator. A simulation on the solar cell optical and electrical losses was done by the Quokka 3 simulator and shows much lower electrical transport loss and a bit higher front surface transmission loss for the one with double layer than nc-SiOx:H (n) single layer.
关键词： Loss analysis,Nanocrystalline silicon oxide,Silicon heterojunction solar cells,Electron transport layer
更新于2025-09-23 15:19:57
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Determining the sequence and backbone structure of a??semi-statisticala?? copolymers as donora??acceptor polymers in organic solar cells
摘要： Organic photovoltaics (OPVs) are attracting significant attention due to the growing demand for economically viable and renewable energy sources. With efficiencies exceeding 16.5%, single junction bulk heterojunction (BHJ) devices are amongst the most promising and are nearing commercialisation. One recent avenue of research has focused on statistical conjugated copolymers. However, a detailed investigation as to why these materials can achieve higher power conversion efficiencies than their regular alternating counterparts is seldom reported. This work describes an investigation into donor–acceptor polymers demonstrating how differing monomer activities can lead to differing microstructures in a simple batch reaction, which in turn demonstrates promising optoelectronic and morphological properties required for organic photovoltaic devices. A one pot condensation polymerisation reaction with three monomers leads to an ABA triblock structure from differing monomer reactivities. This structure in turn leads to visualised phase separation which is possibly linked to an increase in performance. Further to this we report on the reliability of the Stille coupling for the synthesis of conjugated polymers.
关键词： Organic photovoltaics,Donor–acceptor polymers,Bulk heterojunction devices,Statistical conjugated copolymers,Stille coupling
更新于2025-09-23 15:19:57
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Tungsten Dichalcogenide Nanoflake/InGaZnO Thin-Film Heterojunction for Photodetector, Inverter, and AC Rectifier Circuits
摘要： Heterojunction PN diode and inverter circuits are fabricated and presented, combining two-dimensional WSe2 nanoflake and amorphous InGaZnO (a-IGZO) thin film on a glass substrate. A heterojunction p-WSe2/n-IGZO diode exhibits rectifying characteristics and effectively responds to red light (λ = 620 nm) under a reverse bias. The combination of a heterojunction PN diode and IGZO field effect transistor (FET) leads to a diode-load inverter showing a peak voltage gain of about 12 at a supply voltage of 5 V. The same integration from the PN diode and n-FET displays the capability of visible light detection when a reverse-bias voltage is applied to the PN diode. Furthermore, after oxygen plasma treatment on the PN diode, it shows dramatically enhanced on/off rectification ratio of ≈5 × 105 due to the hole doping effect on the WSe2 nanoflake. Such an improved PN diode leads to an alternating current rectifier circuit as integrated with IGZO FET.
关键词： field-effect transistor (FET),inverter,WSe2,InGaZnO (IGZO),heterojunction PN diode,AC rectifier
更新于2025-09-23 15:19:57
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Organic Photovoltaics: Relating Chemical Structure, Local Morphology, and Electronic Properties
摘要： Substantial enhancements in the efficiencies of bulk-heterojunction (BHJ) organic solar cells (OSCs) have come from largely trial-and-error-based optimizations of the morphology of the active layers. Further improvements, however, require a detailed understanding of the relationships among chemical structure, morphology, electronic properties, and device performance. On the experimental side, characterization of the local (i.e., nanoscale) morphology remains challenging, which has called for the development of robust computational methodologies that can reliably address those aspects. In this review, we describe how a methodology that combines all-atom molecular dynamics (AA-MD) simulations with density functional theory (DFT) calculations allows the establishment of chemical structure–local morphology–electronic properties relationships. We also provide a brief overview of coarse-graining methods in an effort to bridge local to global (i.e., mesoscale to microscale) morphology. Finally, we give a few examples of machine learning (ML) applications that can assist in the discovery of these relationships.
关键词： Machine Learning,Density Functional Theory,Organic Photovoltaics,Organic Solar Cells,Bulk-Heterojunction,Electronic Properties,Coarse-Graining Methods,Local Morphology,Chemical Structure,All-Atom Molecular Dynamics
更新于2025-09-23 15:19:57
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Synthesis and Evaluation of Scalable D-A-D ??-Extended Oligomers as p-Type Organic Materials for Bulk-Heterojunction Solar Cells
摘要： The synthesis and characterization of four novel donor-acceptor-donor π-extended oligomers, incorporating naphtha(1–b)thiophene-4-carboxylate or benzo(b)thieno(3,2-g) benzothiophene-4-carboxylate 2-octyldodecyl esters as end-capping moieties, and two different conjugated core fragments, is reported. The end-capping moieties are obtained via a cascade sequence of sustainable organic reactions, and then coupled to benzo(c)(1,2,5)thiadiazole and its difluoro derivative as the electron-poor π-conjugated cores. The optoelectronic properties of the oligomers are reported. The novel compounds revealed good film forming properties, and when tested in bulk-heterojunction organic photovoltaic cell devices in combination with PC61BM, revealed good fill factors, but low efficiencies, due to their poor absorption profiles.
关键词： organic electronics,Cascade organic reactions,fused aromatic rings,organic photovoltaics,π-conjugated oligomers,bulk-heterojunction organic solar cells,direct arylation
更新于2025-09-23 15:19:57
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Physics-based capacitance model of Gate-on-Source/Channel SOI TFET
摘要： A surface potential-based analytical capacitance model is proposed for gate-on-source–channel silicon on insulator (SOI) tunnel ?eld effect transistor (GOSC TFET). The capacitance in the GOSC TFET is evidently shared by the gate-to-source capacitance which reduces the miller capacitance and leads to better switching speed in the circuit application. The effect of drain voltage, gate voltage, gate oxide thickness and source doping on the capacitance has been analysed in detail. The good matching between the modelled and Technology Computer-Aided Design (TCAD) simulated surface potential leads to the accurate calculation of capacitance. The validation of the capacitance model is done by comparing the model result with the simulation result and a good agreement between them validates the model formulation.
关键词： in low power,heterojunction TFETs,carrier
更新于2025-09-23 15:19:57
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Morphological Evolution Induced through Heterojunction of W-decorated NiO Nanoigloos: Synergistic Effect on High-performance Gas Sensors
摘要： Morphological evolution accompanying a surface roughening and the preferred orientation is an effective way to realize a high-performance gas sensor because of its significant potential as a chemical catalyst by chemical potentials and atomic energy states. In this work, we investigated the heterojunction of both-sided W-decorated NiO nanoigloos fabricated through RF sputtering and a soft-template method. Interestingly, the morphological evolution characterized by a pyramidal rough surface and the preferred orientation of the (111) plane was observed upon decorating the bare NiO nanoigloos with W. The underlying mechanism of the morphological evolution was precisely demonstrated based on a van der Drift competitive growth model originating from the oxygen transport and chemical strain in a lattice. The gas sensing properties of W-decorated NiO show an excellent NO2 response and selectivity when compared to other gases. In addition, high response stability was evaluated under interference gas and humidity condition. The synergistic effects on the sensing performance were interpreted based on the morphological evolution of W-decorated NiO nanoigloos.
关键词： Gas sensor,Nanostructure,Morphological evolution,Heterojunction,NO2
更新于2025-09-19 17:15:36
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Fabrication of novel AgBr/Bi <sub/>24</sub> O <sub/>31</sub> Br <sub/>10</sub> composites with excellent photocatalytic performance
摘要： Novel porous AgBr/Bi24O31Br10 (AB/BOB) heterojunction composites were prepared by a hydrothermal calcination-ion exchange route and their physico-chemical properties were characterized by XRD, XPS, SEM, EDX, UV-vis DRS, BET and electrochemical measurements. The photocatalytic activity of the composites consisting of different AB/BOB mass ratios was evaluated by degradation of methylene blue (MB) under visible light irradiation. Compared with pure AB and BOB, the porous 20% AB/BOB composite exhibits much enhanced photocatalytic activity with good cycling stability. The significant enhancement in photoactivity is contributed to by both a high adsorption capacity and the separation efficiency of photo-generated electron–hole (e–h+) pairs via a Z-scheme mechanism. In addition, radical scavenging experiments confirm that the reactive ?OH radicals play an important role in the photocatalytic reaction. The novel AB/BOB heterojunction composites could have a promising application in treatment of various dyestuff wastewaters on a large scale.
关键词： AgBr/Bi24O31Br10,heterojunction,Z-scheme mechanism,photocatalysis,visible light
更新于2025-09-19 17:15:36
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Reducing the surface recombination during light-driven water oxidation by core-shell BiVO4@Ni:FeOOH
摘要： The photocurrent of BiVO4 is limited by surface recombination not surface catalysis, which is currently reported as the main restrict factor for high efficiency photo-electrochemical (PEC) water splitting. To solve this problem, an ultrathin Ni:FeOOH (~ 8 nm) modified nanoporous BiVO4 photoanode (BiVO4@Ni:FeOOH) was constructed with core-shell structure for PEC water oxidation. Attributed to the p-n hetero-junction formed between BiVO4 and Ni:FeOOH, the photocurrent density of BiVO4@Ni:FeOOH increased by a factor of 11 (2.86 mA cm-2 at 1.23 V vs. RHE), together with ~ 180 mV negative shift of onset potential under AM 1.5 G irradiation (100 mW cm-2) in comparison to the pristine BiVO4. More importantly, detailed insight into the fate of the photo-generated charge carriers at the surface is investigated. Intensity modulated photocurrent spectroscopy (IMPS) is used to investigate the surface carrier dynamics of BiVO4 and BiVO4@Ni:FeOOH. IMPS results and hole scavenger measurement (HSM) certify the main role of Ni:FeOOH is to improve surface recombination by largely decreasing the surface recombination rate constant (krec), not surface catalysis. This work demonstrates Ni:FeOOH can facilitate local surface kinetics and reduce recombination rates as well and be used in other photoelectrodes especially the photoanodes with surface defects for PEC water splitting.
关键词： Core-shell,intensity modulated photocurrent spectroscopy,p-n heterojunction,surface recombination
更新于2025-09-19 17:15:36
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Perspective on construction of heterojunction photocatalysts and the complete utilization of photogenerated charge carriers
摘要： Semiconductor photocatalysis has received tremendous attention as a promising way for solving the worldwide energy and environment issues. Many efforts have been devoted to developing distinctive morphology and various semiconductor-based composite photocatalysts for enhancing photocatalytic activity in recent years. However, it is still a great challenge and imperative to profoundly understand the transfer mechanisms and to realize complete utilization of photoexcited charge carriers. This perspective for the first time highlights the inner impetus of the photogenerated charge carrier migration (band-band and Z-scheme transfers) over composite photocatalysts. The notion of relative p-n junction for photocatalysis and the corresponding design principle of Z-scheme photocatalysts are introduced first. Then, simultaneous utilization of photogenerated electrons and holes for photocatalytic selective redox syntheses in one reaction system is recommended. The proposed reaction systems have characteristics of the environmentally friendly, atom economy, synergistic effect and high efficiency. Finally, the challenges and opportunities of photocatalysis are outlined and a perspective is given. We hope that the perspective review could give an inspiration for the fundamental research and guide the research direction of photocatalysis.
关键词： Z-scheme,Inner impetus,Photocatalytic redox,Heterojunction photocatalyst,Relative p-n junction
更新于2025-09-19 17:15:36