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We report on the tunnel oxide passivated contact (TOPCon) using a crystalline nanostructured silicon-based layer via an experimental and numerical simulation study. The minority carrier lifetime and implied open-circuit voltage reveals an ameliorated passivation property, which gives the motivation to run a simulation. The passivating contact of an ultra-thin silicon oxide (1.2 nm) capped with a plasma enhanced chemical vapor deposition (PECVD) grown 30 nm thick nanocrystalline silicon oxide (nc-SiOx), provides outstanding passivation properties with low recombination current density (Jo) (~1.1 fA/cm2) at a 950 °C annealing temperature. The existence of a thin silicon oxide layer (SiO2) at the rear surface with superior quality (low pinhole density, Dph < 1 × 10−8 and low interface trap density, Dit ≈ 1 × 108 cm−2 eV−1), reduces the recombination of the carriers. The start of a small number of transports by pinholes improves the fill factor (FF) up to 83%, reduces the series resistance (Rs) up to 0.5 Ω cm2, and also improves the power conversion efficiency (PEC) by up to 27.4%. The TOPCon with a modified nc-SiOx exhibits a dominant open circuit voltage (Voc) of 761 mV with a supreme FF of 83%. Our simulation provides an excellent match with the experimental results and supports excellent passivation properties. Overall, our study proposed an ameliorated knowledge about tunnel oxide, doping in the nc-SiOx layer, and additionally about the surface recombination velocity (SRV) impact on TOPCon solar cells.

Photovoltaic (PV) panels are generally treated as the most dependable components of PV systems; therefore, investigations are necessary to understand and emphasize the degradation of PV cells. In almost all specific deprivation models, humidity and temperature are the two major factors that are responsible for PV module degradation. However, even if the degradation mode of a PV module is determined, it is challenging to research them in practice. Long-term response experiments should thus be conducted to investigate the influences of the incidence, rates of change, and different degradation methods of PV modules on energy production; such models can help avoid lengthy experiments to investigate the degradation of PV panels under actual working conditions. From the review, it was found that the degradation rate of PV modules in climates where the annual average ambient temperature remained low was -1.05% to -1.16% per year, and the degree of deterioration of PV modules in climates with high average annual ambient temperatures was -1.35% to -1.46% per year; however, PV manufacturers currently claim degradation rates of up to -0.5% per year.

In this paper, we analysed and implement clear sky and array performance models to achieve maximum electrical energy produced from the photovoltaic (PV) panel. The selected models just not only include location dependent parameters but also include environmental factors such as Linke Turbidity (include aerosols, absorption due to assorted gases, Rayleigh scattering), cloud cover, albedo, perceptible water vapour. 250 W PV panel was used as a reference to check the output electrical energy in a given location by inputting the latitude and longitude of a location. It is concluded that 27° facing south is the optimized tilt angle for every locations having latitude at north direction and longitude at east direction. By taking the example of location Nagpur India (21.14° N, 79.08° E), a difference of only 0.35 % is reported when comparing the computed electrical energy with actual electrical energy that have been acquired by using pyranometers, pyrheliometers and illuminance meters installed by the National Renewable Energy Laboratory (NREL). So, a good approximation of electrical energy can be computed by combining clear sky and array performance models.

Characterization of pore systems in subsurface systems is of great importance for predicting the properties of rocks and classifying the subsurface systems. Geometric features have been used widely for this aim, but topological characteristics of the pore structures are not studied much. In fact, accurate characteristics of pore space should comprise both its geometric and topological properties. In this paper, the above vital characteristics are comprehensively studied based on direct experimental results. Besides, previous studies aiming at linking fractal dimension analysis to pore space are often based on limited sources of information, which are the mercury injection capillary pressure (MICP) and nuclear magnetic resonance (NMR). In this paper, the scanning electron microscope (SEM), MICP, NMR, and X-ray computed tomography (X-ray CT) experiments are all used to characterize the geometric and topological properties of pore space of several low-permeability porous media. Based on our observations, the advantages and disadvantages of the above techniques in characterizing the pore structure are also summarized. Moreover, the differences of these three experiments are quantified using fractal dimension. The results indicate that the NMR technique is a promising tool for characterizing geometric features of pore systems as it can cover more details than other techniques. Most of geometric, topological, fractal and transport properties of pore space can be obtained from X-ray CT method, which is unique among all the methods. In addition, the 3D fractal dimensions of pore systems obtained from NMR is smaller than that from MICP, which is due more ultra-micropores captured by NMR that smooth the surface of the pore systems. Finally, a novel method constrained by a new pore shape factor for calculating the pore size from 2D images is proposed by which the pore-size distributions are compared more effectively.

The screen-printing process for making good contact of electrodes with the top layer of solar cells is crucial for enhancing the electrical properties of a solar cell. This paper reports the experimental approach adopted for the process of electrode formation and the resulting shape of electrodes in silicon-based heterojunction (SHJ) solar cells. It was observed that good contact between electrodes and the top transparent conductive oxide (TCO) layer strongly depends on the squeegee pressure, curing temperature, and curing time. By optimizing the squeegee pressure at 0.350 MPa, snap-off distance of 1.4 mm, squeegee speed of 80 mm sec−1, curing temperature of 180 °C, and curing time of 30 min, respectively for which the height to width ratio (aspect ratio) of the fabricated electrodes was achieved around 0.66. The results have been verified through 3D laser profiler, field emission scanning electron microscopy (FE-SEM), transfer length method (TLM), and Light current-voltage (LIV) measurements. The SHJ solar cells were fabricated using an optimized condition and successfully achieved splendid properties of short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), and efficiency (η) up to 40.57 mA cm−2, 723 mV, 81.03%, and 23.79%, respectively.

Typically, a 355 nm laser is not sufficient for inducing photochemical ablation and leads to photothermal effects such as melting and recasting. Consequently, most previous studies on the irradiation of polyimide (PI) with such lasers have focused on temperature distribution on the surface and variations in the absorption properties of PI depending on the temperature and time. Herein, the authors demonstrate ablation without thermal effects on the surface of PI using a 355 nm pulse nanosecond laser near the threshold fluence. For ablation without thermal effects, the ablated and nonablated areas can be clearly distinguished in the area exposed to the laser. The interface between these areas, that is, the ablation shape, became wider with increasing laser fluence, even when the spot size remained unchanged; also, the shape of the ablated area was related to the laser intensity distribution. Ablation with thermal effects began to appear in the nonablated areas at higher laser fluence. This study shows that PI, which is physically stable and relatively inexpensive, can be used to develop cation exchange membranes, which can be applied to organic flow cells as well as microbial fuel cells.

Antireflection coatings (ARCs) on an optical substrate appear to be highly effective for reducing reflectance for optical and photovoltaic (PV) panel applications. In this perspective, we have prepared and investigated the performance of silica nanoparticles (SNPs) ARC through a sol–gel process for the PV module applications. The ∼160-nm-thick sol–gel prepared SNPs have been coated on a glass substrate using the spin coating technique. The further vapor-phase treatment of hexamethyldisilazane (HMDS) on silica-coated glass results in contamination-resistant due to the existence of trimethylsilyl groups. The resultant-coated glass exhibits improvement in transmission by ∼3 % while reducing the refractive index value up to 1.17. The solar cell tested undercoated glass notifies the increase in current density of 34.24 to 35.17 mA / cm2 and improves the overall efficiency up to 3.13% as compared to the untreated glass. The results obtained in our study suggest an important future direction for the use of HMDS-treated SNPs in an outdoor PV module and solar collector applications.

Porous polymer films have been investigated for various applications. The conventional method forms microporous structures throughout a film. This paper presents a new process for forming micro/nano-porous patterns on a polyimide membrane surface using a laser and a blowing agent only in selected areas. A blowing agent was mixed in a polyimide, and the mixture was then irradiated with a laser to instantaneously heat it to the decomposition temperature of the blowing agent. Subsequently, micro/nano-porous patterns were created only in regions irradiated with the laser owing to the explosion of the blowing agent. The micro/nano-porous patterns were fabricated using 355-nm ultraviolet pulse laser processing. The pores of the porous structures were closed or open, depending on the quantity of blowing agent, laser fluence, and pulse overlap ratio. The experimental results showed that the pore density, pore size, and processing time could be adjusted. In addition, porous patterning was formed selectively and locally. Recently, micro-/nano porous patterned films have been widely used as absorbents, support cells, and sensors in industrial fields and they have considerable application potential in various fields.

Numerical simulation and experimental techniques were used to investigate lithium fluoride (LiFx) films as an electron extraction layer for the application of silicon heterojunction (SHJ) solar cells, with a focus on the paths toward excellent surface passivation and superior efficiency. The presence of a 7 nm thick hydrogenated intrinsic amorphous silicon (a-Si:H(i)) passivation layer along with thermally evaporated 4 nm thick LiFx resulted in outstanding passivation properties and suppresses the recombination of carriers. As a result, minority carrier lifetime (τ eff) as well as implied open-circuit voltage (iVoc) reached up 933 μs and iVoc of 734 mV, accordingly at 120 °C annealing temperature. A detailed simulated study was performed for the complete LiFx based SHJ solar cells to achieve superior efficiency. Optimized performance of SHJ solar cells using a LiFx layer thickness of 4 nm with energy bandgap (Eg) of 10.9 eV and the work function of 3.9 eV was shown as: Voc = 745.7 mV, Jsc = 38.21 mA cm−2, FF = 82.17%, and η = 23.41%. Generally, our work offers an improved understanding of the passivation layer, electron extraction layer, and their combined effects on SHJ solar cells via simulation.

The efficiency of silicon heterojunction solar cells is limited by various factors including low surface passivation, parasitic absorption, and recombination losses. Herein, the surface passivation quality of crystalline silicon solar cells is improved by a hybrid passivation structure including a silicon heterojunction contact at the front side and a stack of tunneling oxide with n-type nano-crystalline silicon oxide (nc-SiOx(n)) passivating contact at the rear side. A passivation contact with thin silicon oxide (SiO2) and poly-silicon was previously proposed to enhance the rear surface passivation. In our study, the poly-silicon layer is swapped with the nc-SiOx(n) layer to improve the effective surface passivation, electrical properties, recombination losses, and carrier selectivity. The hybrid passivation structure shows significant passivation improvement with lifetime (τeff) of 2696 μs and implied open-circuit voltage (i-Voc) of 735 mV as compared with both-sides traditional silicon heterojunction (1650 μs, 719 mV) and tunneling passivation contact (2146 μs, 725 mV). The hybrid solar cell shows a potential performance as; open circuit voltage (Voc) = 724 mV, short circuit current (Jsc) = 38.95 mA/cm2, fill factor (FF) of 75.9%, efficiency (η) = 21.4%. However, there is room to further improve the overall cell performance.

The architecture and quality of lacustrine turbidites that act as petroleum reservoirs are less well documented. Reservoir architecture and multiscale heterogeneity in turbidites represent serious challenges to production performance. Additionally, establishing a hierarchy profile to delineate heterogeneity is a challenging task in lacustrine turbidite deposits. Here, we report on the turbidites in the middle third member of the Eocene Shahejie Formation (Es3), which was deposited during extensive Middle to Late Eocene rifting in the Dongying Depression. Seismic records, wireline log responses, and core observations were integrated to describe the reservoir heterogeneity by delineating the architectural elements, sequence stratigraphic framework and lithofacies assemblage. A petrographic approach was adopted to constrain microscopic heterogeneity using an optical microscope, routine core analyses and X-ray diffraction (XRD) analyses. The Es3m member is interpreted as a sequence set composed of four composite sequences: CS1, CS2, CS3 and CS4. A total of forty-five sequences were identified within these four composite sequences. Sand bodies were mainly deposited as channels, levees, overbank splays, lobes and lobe fringes. The combination of fining-upward and coarsening-upward lithofacies patterns in the architectural elements produces highly complex composite flow units. Microscopic heterogeneity is produced by diagenetic alteration processes (i.e., feldspar dissolution, authigenic clay formation and quartz cementation). The widespread kaolinization of feldspar and mobilization of materials enhanced the quality of the reservoir by producing secondary enlarged pores. In contrast, the formation of pore-filling authigenic illite and illite/smectite clays reduced its permeability. Recovery rates are higher in the axial areas and smaller in the marginal areas of architectural elements. This study represents a significant insight into the reservoir architecture and heterogeneity of lacustrine turbidites, and the understanding of compartmentalization and distribution of high-quality sand reservoirs can be applied to improve primary and secondary production in these fields.

An automatic sedimentary microfacies identification technique is developed based on the deep process neural network (DPNN), which consist several neurons and general non-time-varying neurons arranged in a certain topological structure. In this technique, the features of the shape and amplitude of logging curves are considered to form the category outputs. Combined with the deep learning theory, the diversity of the process features of logging curves and the complexity of combined features of multiple geophysical logging information are considered, and DPNN is created through the stacked superimposition of deep belief network and BP classifier. The technique maintains the structure and information relevance of process signal data and can characterize the distribution features of logging curves automatically, and classify the process signals directly. The theoretical nature and performance of the improved algorithm is tested and validated by some field examples.

With the growing worldwide demand for clean, reliable, and economical energy supply, Photovoltaic (PV) modules have raised the bar for the field over the last years. However, PV modules have shown some shortcomings as environment temperature influences not only the maximum power generation but also the life expectancy of the module. PV reliability has become a topic of extreme importance driven by the extension of the warranty period over the years. This study investigates the degradation of solder joints. A 2-D Finite Element Model (FEM) has been computed to evaluate the lifetime of the solder joints and the cell power drop using accelerated thermal cycling tests in the range of −40 to 85 °C according to IEC 61215 standard. 2 models were used to predict the lifetime. In addition, 5 PV modules were conducted to thermal cycling tests to validate the model. The results reveal that during the thermal cycling test, the rear solder is damaged in a much earlier stage than the top solder. The deterioration of the rear solder area becomes steep after 1000 cycles and the power loss of the module reaches 2% between 600 and 750 thermal cycles depending upon the mathematical model. When compared to experimental results, the Coffin-Mason model is more accurate, with a maximum data disparity of 4.3%. A solder without any residual stress will eventually pass the 600TC test according to CSA/ANSI C450–18 and IEC TS 63209 ED1 standards. These findings inform on the solder joint durability which is an important parameter for the reliability analysis of a PV module.

Contamination and weather-resistant property of anti-reflection coating obtained by the sol-gel process is crucial for practical applications. In this work, we used the stӧber method to make silica nanoparticles and used the spin coating approach to apply them to a polymethylmethacrylate (PMMA) substrate. We adopted a low-temperature surface treatment approach by placing silica-coated PMMA in chloroform, aqueous ammonia, and hexamethyldisilazane vapor-phase environment. The treated PMMA exhibits a maximum transmittance of 95.68% in the wavelength range of 500–1100 nm. The treated PMMA showed a decrease of 0.21% transmittance after checking it with contamination and weather-resistant test. The treated PMMA exhibits a water contact angle of 115.96°, making it hydrophobic which is almost ten times that of untreated PMMA. An increase in the current density from 33.23 to 34.37 mA/cm2 and an improvement in the efficiency of 3.54% was observed when the treated PMMA was placed onto a solar cell instead of uncoated PMMA for lightweight photovoltaic module applications.

Xihu Depression is a relatively new petroleum exploration area in East China Sea Basin. Pinghu Formation is one of the most important oil-bearing formations in the depression. Due to the low exploration level of the depression, paleosalinity and deposition environment of the depression in Pinghu stage is not clear. Element geochemical analysis of samples from different structural units is used to study ancient water salinity and reveal the depositional environment. B/Ga ratio, which is sensitive to paleosalinity in study area, is 0.9–4.0 and indicates characteristics of mixed water of fresh and salt water. There is a threshold for Sr/Ba in water salinity study in the study area. When Sr/Ba ratio is lower than 0.15, it cannot be used as an indicator for salinity and ancient water body type. Equivalent boron content calculated by Walker's method is lower than 150 ppm. Paleo salinity from boron content calculated by Couch's method is 2.97‰–9.61‰ and the average is 4.8‰. Based on the above mentioned results, ancient water body of Xihu Depression in Pinghu stage has typical characteristics of brackish water and it belongs to oligohaline and mesohaline water. Combining paleogeomorphology and sedimentary facies distribution in the study area, paleowater body in Xihu Depression during Pinghu stage is transitional mixed water influenced by terrigenous diluted water. Paleosalinity contour lines extend on plane from north to the south and are parallel to paleo-coastline. Paleosalinity increases from the west to the east. Influenced by freshwater of deltas at western part of the depression, high abnormal salinity values occur around the wells M1 and L1 where salinity contour lines curve westward.

Pore size distribution and associated heterogeneities of thinly bedded beach-bar sandstone reservoir from upper fourth member of Eocene Shahejie Formation (Es4s) are characterized with the help of mercury injection capillary pressure (MICP) and nuclear magnetic resonance (NMR) transversal relaxation time (T2) data. Permeability and porosity are two represented important characteristics of rocks that control the movement and storage of fluids. The aim of this paper is to establish relationships between pore throat sizes and reservoir quality. The results derived from thin-section petrography, scanning electron microscopy (SEM), MICP, NMR T2 relaxation time, and 3D micro-CT (μ-CT) are compared to characterize pore space dimensions and types comprehensively. Average pore throat size from MICP ranges between 0.47 μm and 2.83 μm while maximum pore throat size ranges between 2.48 μm and 7.36 μm. The combination of pore size distribution obtained from MICP and NMR seems appropriate to cover the range of pore size from beach-bar sand and overcome the individual method limits. Afterwards, digital 3D μ-CT tomographic images are used to characterize and visualize pore space and pore network model to compare with the experimental data. MICP and NMR experiment showed generally bimodal (meso and micro) pore size distribution. Usually mesopore corresponding to intergranular pores is dominant, while heavily cemented sandstones show large amounts of intercrystalline micropores. Complex and heterogeneous beach-bar sandstone reservoir requires comprehensive study program to evaluate the reservoir.

There is a growing interest in characterizing the pore structure of reservoir rocks using the low field nuclear magnetic resonance technique. The transverse surface relaxivity is widely appreciated as the most significant parameter to connect the transverse relaxation (T2) time and the pore size by scientists. In this study, we reviewed long-established and recently developed methods to predict the surface relaxivity over the last few decades. Moreover, the advantages, shortcomings, as well as the applications of the methods were discussed. What's more, the potential causes of affecting the surface relaxivity such as mineralogical compositions, reservoir conditions, fluid properties, and magnetic field strengths were investigated to analyze the controlling factors of the surface relaxivity. Based on the review and analysis, we recommended a composited experiment to measure the surface relaxivity and proposed a possible workflow to obtain the variable surface relaxivity. The review section shows that the surface relaxivity is generally calculated based on the specific surface area. There is no universally accepted method since each of the experiments only probes a part of the pore system or resolves pore size at a different length scale, and it is better to characterize the full-scale pore space using multi-scale experiments. In addition, the constant surface relaxivity may not hold true for heterogeneous reservoir rocks with wide pore size distributions and the presence of paramagnetic minerals. It is a trend to use more than one surface relaxivity according to petrophysical facies or pore types. Multiple regressions may also serve as an effective way to get variable surface relaxivities. Further work needs to be done to develop a comprehensive understanding of the surface relaxivity, especially the influence of the spatial distribution of paramagnetic minerals which are extensively distributed in unconventional reservoirs such as shale and coal.

Polymethylmethacrylate (PMMA) is an ideal replacement of glass where impact of weight is a serious issue. PMMA surface can be modified to make it highly transparent substrate. PMMA substrate was etched using a plasma etching system with oxygen plasma. CaF2 was deposited on to the etched PMMA via vacuum thermal evaporation to create anti-reflection coating. The effects of the treated PMMA were analysed using different characterisation techniques. An average increase in transmittance of approximately 4% was observed on 50 W RF power treated PMMA, compared to untreated PMMA in the broadband spectrum of 400–1100 nm. An enhancement in short circuit current from 36.71 to 37.62 mA/cm2 and an increase in efficiency of 2.35% was achieved when the treated PMMA was placed on a solar cell as a front cover sheet to model a lightweight photovoltaic module. These findings indicate the possibility of improving the surface morphology, optical and electrical characteristics of PMMA via treatment for photovoltaic applications.

Thin-bedded beach-bar sandstone reservoirs are common in the Eocene Shahejie Formation (Es4s) of Niuzhuang Sag, along the southern gentle slope of the Dongying Depression. Here we report on the link between sequence stratigraphy, sedimentary facies and diagenetic effects on reservoir quality. Seismic data, wireline logs, core observations and analyses are used to interpret depositional settings and sequence stratigraphic framework. Petrographic study based on microscopic observation of optical, cathodoluminescence (CL), confocal laser scanning (LSCM) and scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses were used to describe the fabric, texture, allogenic and authigenic mineralogy of these highly heterogeneous sandstone reservoirs. The Es4s interval is interpreted as third-order sequence, composed of a lowstand systems tract (LST), a transgressive systems tract (TST) and a highstand systems tract (HST). On the fourth order, twenty-nine parasequences and seven parasequence sets have been identified. Sand bodies were deposited mainly in the shoreface shallow lake beach-bar (clastic beach-bar), semi-deep lake (carbonate beach-bar) and the fluvial channels. The depositional and diagenetic heterogeneities were mainly due to the following factors: (1) fine grain size, poor sorting, and continuous thin inter-bedded mud layers with siltstone/fine-sandstone having argillaceous layers in regular intervals, (2) immature sediment composition, and (3) even with the dissolution of grains and several fractures, destruction of porosity by cementation and compaction. Secondary pores from feldspar dissolution are better developed in sandstones with increased cementation. Grain coating smectite clays preserved the primary porosity at places while dominating pore filling authigenic illite and illite/smectite clays reduced permeability with little impact on porosity. Due to the high degree of heterogeneity in the Es4s beach-bar interval, it is recognized as middle to low permeable reservoir. The aforementioned study reflects significant insight into the understanding of the properties of the beach-bar sands and valuable for the comprehensive reservoir characterization and overall reservoir bed quality.

The low field nuclear magnetic resonance (NMR) spectroscopy has been widely used to characterize the longitudinal and transversal relaxation (T1-T2) spectrum of unconventional resources such as shale gas and tight oil containing significant proportions of kerogen and bitumen. However, it requires exquisite design of the acquisition model and the inversion algorithm due to the fast relaxation nature of the kerogen and bitumen. A new direct two dimensional (2D) inversion algorithm combined the iterative truncated singular value decomposition (TSVD) and the Akaiake Information Criterion (AIC) is presented to perform the data inversion efficiently. The fluid component decomposition (FCD) is applied to construct the forward T1-T2 model of the kerogen, and numerical simulations are conducted to investigate factors which may influence inversion results including echo spacing, recovery time series, signal to noise ratio (SNR), and the maximal iteration time. Results show that the T2 component is heavily impaired by the echo spacing, whereas the T1 component is influenced by the recovery time series but with limited effects. The inversion precision is greatly affected by the quality of the data. The inversed spectrum deviates from the model seriously when the SNR of the artificial noise is lower than 50, and the T2 component is more sensitive to the noise than the T1 component. What's more, the maximal iteration time can also affect the inversion result, especially when the maximal iteration time is smaller than 500. Proper acquisition and inversion parameters for the characterization of the kerogen are obtained considering the precision and the computational cost.

It is difficult to extract quantitative information of pore space from thin section. A novel method to characterize the pore space using multifractal analyses is presented, with the help of mercury injection capillary pressure (MICP) and nuclear magnetic resonance (NMR) transversal relaxation time ( T 2 ) data. Thin sections were processed via multi-threshold segmentation using particle swarm optimization (PSO) algorithm to obtain binary images containing pore space and mineral matrix. After multifractal analyses of binary images, the interrelationship between multifractal parameters and pore structure is investigated in detail. A crossplot for pore structure classification is put forward with types predefined by MICP and NMR experiments. The result shows that different pore types demonstrate their unique multifractal characteristics. Multifractal dimensions are positively correlated with the median capillary pressure, whereas negatively correlated with average pore radius and the T 2 geometric value. D min and D 0 can be served as good indicators of pore structure types in the case study. This study provides an effective way of pore structure characterization and classification based on thin section, especially for regions without MICP and NMR experiments.