Analysis of the Thermal Stress for Combined Electrode of Soldered Crystalline Silicon Solar Cells under Temperature Field

Based on the theory of material mechanics and thermal stress analysis, the stress distribution of combined electrode for crystalline silicon solar module was studied for the first time. The shear stress and normal stress distribution of soldered structure for crystalline silicon solar cells under the thermal field were discussed. And the results show that the stress distribution is not simply linear relationship as some results found. But there is a stress concentration at the edge, which was considered as the true reason that caused microcracks at the edge of soldered solar cells. The conclusions we got in this paper provide a theoretical basis for deceasing the breakage rates of soldered crystalline silicon solar cells and improving the reliability of crystalline silicon solar modules

High‐Efficiency Graphene‐Oxide/Silicon Solar Cells with an Organic‐Passivated Interface

A breakthrough in graphene-oxide/silicon heterojunction solar cells is presented in which edge-oxidized graphene and an in-plane charge transfer dopant (Nafion) are combined to form a high-quality passivating contact scheme. A graphene oxide (GO):Nafion ink is developed and an advanced back-junction GO:Nafion/n-Si solar cell with a high-power conversion efficiency (18.8%) and large area (5.5 cm2) is reported. This scalable solution-based processing technique has the potential to enable low-cost carbon/silicon heterojunction photovoltaic devices

Interdigitated Back‐Contacted Carbon Nanotube–Silicon Solar Cells

Carbon/silicon heterojunctions provide a new perspective for silicon solar cells and in particular those made from carbon nanotubes (CNTs) have already achieved industrial-level power conversion efficiency and device size when using organic passivation and a back-junction design. However, the current state of the art device geometry for silicon photovoltaics is the interdigitated back contact (IBC) cell and this has yet to be demonstrated for CNT/Si solar cells due to the complexity of fabricating the required patterns. Herein, IBC-CNT solar cells are demonstrated via the simple spin coating of a conductive hole-selective passivating film and the evaporation of buried silicon oxide/magnesium electron-selective contacts for both polarities. The CNT coverage area fraction (fCNT) and the gap between the two polarities are optimized to minimize electrical shading loss and ensure high photocarrier collection. Large-area (4.76 cm2) highly efficient (17.53%) IBC-CNT solar cells with a Voc of 651 mV and Jsc of 40.56 mA cm−2 are demonstrated and are prepared with one alignment step for the CNT/Si contact, and photolithographic-free and room-temperature processes. These performance parameters are among the best for solution-processed dopant-free IBC schemes and indicate the feasibility of using low-dimensional carbon materials in IBC solar cells

Power Degradation Caused by Snail Trails in Urban Photovoltaic Energy Systems

AbstractIn recent years, a discoloration defect called as the snail trials emerged on crystalline silicon solar module in urban photovoltaic energy systems. It resulted in power degradation, and caused a serious concern about effects of this phenomenon on crystalline silicon solar modules, but very few publications have dealt with this phenomenon. In this paper, the crystalline silicon solar modules with snail trials are investigated by I-V and P-V characteristics, electroluminescence (EL) technique, thermography analysis, and energy production in photovoltaic power plant. The obtained results show that the snail trails may affect output of power for crystalline silicon solar modules compared with reference module, the energy production measured was about 9.1% lower than the normal array

Zinc oxide TCOs (Transparent Conductive Oxides) and polycrystalline silicon thin-films for photovoltaic applications

Transparent conductive oxides (TCOs) and polycrystalline silicon (poly-Si) thin-filmsare very promising for application in photovoltaics. It is extremely challenging to developcheap TCOs and poly-Si films to make photovoltaic devices. The aim of this thesis is tostudy sputtered aluminum-doped ZnO TCO and poly-Si films by solid-phasecrystallization (SPC) for application in low-cost photovoltaics. The investigated aspectshave been (i) to develop and characterize sputtered aluminum-doped ZnO (ZnO:Al) filmsthat can be used as a TCO material on crystalline silicon solar cells, (ii) to explore thepotential of the developed ZnO:Al films for application in ZnO:Al/c-Si heterojunctionsolar cells, (iii) to make and characterize poly-Si thin-films on different kinds of glasssubstrates by SPC using electron-beam evaporated amorphous silicon (a-Si) [referred toas EVA poly-Si material (SPC of evaporated a-Si)], and (iv) to fabricate EVA poly-Sithin-film solar cells on glass and improve the energy conversion efficiency of these cellsby post-crystallization treatments.The ZnO:Al work in this thesis is focused on the correlation between film characteristicsand deposition parameters, such as rf sputter power (Prf), working gas pressure (Pw), andsubstrate temperature (Tsub), to get a clear picture of film properties in the optimizedconditions for application in photovoltaic devices. Especially the laterally non-uniformfilm properties resulting from the laterally inhomogeneous erosion of the target materialare investigated in detail. The influence of Prf, Pw and Tsub on the structural, electrical,optical and surface morphology properties of ZnO:Al films is discussed. It is found thatthe lateral variations of the parameters of ZnO:Al films prepared by rf magnetronsputtering can be reduced to acceptable levels by optimising the deposition parameters.ZnO:Al/c-Si heterojunction solar cells are fabricated and characterized to demonstratethe feasibility of the fabricated ZnO:Al films for application in heterojunction solar cells.In this application, expensive indium-tin oxide (ITO) is usually used. Under the standardAM1.5G spectrum (100 mW/cm2, 25 °C), the best fabricated cell shows an open-circuitvoltage of 411 mV, a short-circuit current density of 30.0 mA/cm2, a fill factor of 66.7 %,and a conversion efficiency of 8.2 %. This is believed to be the highest stable efficiencyever reported for this type of cell. By means of dark forward currentdensity-voltage-temperature (J-V-T) measurements, it is shown that the dominant currenttransport mechanism in the ZnO:Al/c-Si solar cells, in the intermediate forward biasvoltage region, is trap-assisted multistep tunneling.EVA poly-Si thin-films are prepared on four types of glass substrates (planar and texturedglass, both either bare or SiN-coated) based on evaporated Si, which is a cheaper Sideposition method than the existing technologies. The textured glass is realized by theUNSW-developed AIT process (AIT = aluminium-induced texture). The investigation isconcentrated on finding optimized process parameters and evaluating film crystallizationquality. It is found that EVA poly-Si films have a grain size in the range 0.8-1.5 μm, anda preferential (111) orientation. UV reflectance and Raman spectroscopy measurementsreveal a high crystalline material quality, both at the air-side surface and in the bulk.EVA cells are fabricated in both substrate and superstrate configuration. Special attentionis paid to improving the Voc of the solar cells. For this purpose, after the SPC process, thesamples receive the two post-crystallization treatments: (i) a rapid thermal anneal (RTA),and (ii) a plasma hydrogenation. It is found that two post-crystallization treatments morethan double the 1-Sun Voc of the substrate-type cells. It is demonstrated that RTAimproves the structural material quality of the cells. Furthermore, a hydrogenation step isshown to significantly improve the electronic material quality of the cells.Based on the RTAd and hydrogenated EVA poly-Si material, the first mesa-type EVAcells are fabricated in substrate configuration, by using sputtered Al-doped ZnO as thetransparent front contact. The investigation is focused on addressing the correlationbetween the type of the substrate and cell performance. Optical, electrical andphotovoltaic properties of the devices are characterized. It is found that the performanceof EVA cells depends on the glass substrate topography. For cells on textured glass, theAIT texture is shown to have a beneficial effect on the optical absorption of EVA films. Itis demonstrated that a SiN barrier layer on the AIT-textured glass improves significantlyboth the crystalline quality of the poly-Si films and the energy conversion efficiency ofthe resulting solar cells. For cells on planar glass, a SiN film between the planar glass andthe poly-Si film has no obvious effect on the cell properties. The investigations in thisthesis clearly show that EVA poly-Si films are very promising for poly-Si thin-film solar cells on glass

Implementation of Tunneling Junction Passivated Contact Concept in Flexible CIGS Solar Cells

Abstract In today's state‐of‐the‐art high‐efficiency silicon solar cells need to be inserted a thin insulating layer in order to reduce the recombination losses between the carrier transport layer and Si surface, which can form a tunneling junction (TJ), thus increasing the performance of the TJ solar cells comparable with the pn junction structure. However, the copper indium gallium selenium (CIGS) solar cells inevitably lead to the losses of the carrier transport due to the interface which is widely assumed as the pn‐heterojunction. Herein, the TJ solar cells, aiming to enhance the performance of the solar cells, are fabricated by inserting the TiO2 between CIGS/CdS interface deposited by atomic layer deposition (ALD). By inserting the TiO2 insulating layer, the CIGS/TiO2/CdS structure can be effectively reduced the interface recombination, which leads to a reduced band bending in the p‐CIGS surface and compromises its field‐effect passivation. As a result, the CIGS solar cell with the tunneling junction achieves the 15.57% based on the stainless steel (SS) substrate, by introducing a barrier layer and doping NaF. These results provide an important preliminary foundation for the development of the CIGS solar cells with the tunneling junction structure

Activation of neuronal N-methyl-d-aspartate receptor plays a pivotal role in Japanese encephalitis virus-induced neuronal cell damage

Abstract Background Overstimulation of glutamate receptors, especially neuronal N-methyl-d-aspartate receptor (NMDAR), mediates excitatory neurotoxicity in multiple neurodegenerative diseases. However, the role of NMDAR in the regulation of Japanese encephalitis virus (JEV)-mediated neuropathogenesis remains undisclosed. The primary objective of this study was to understand the function of NMDAR to JEV-induced neuronal cell damage and inflammation in the central nervous system. Methods The effect of JEV-induced NMDAR activation on the progression of Japanese encephalitis was evaluated using the primary mouse neuron/glia cultures and a mouse model of JEV infection. A high-affinity NMDAR antagonist MK-801 was employed to block the activity of NMDAR both in vitro and in vivo. The subsequent impact of NMDAR blockade was assessed by examining the neuronal cell death, glutamate and inflammatory cytokine production, and JEV-induced mice mortality. Results JEV infection enhanced the activity of NMDAR which eventually led to increased neuronal cell damage. The data obtained from our in vitro and in vivo assays demonstrated that NMDAR blockade significantly abrogated the neuronal cell death and inflammatory response triggered by JEV infection. Moreover, administration of NMDAR antagonist protected the mice from JEV-induced lethality. Conclusion NMDAR plays an imperative role in regulating the JEV-induced neuronal cell damage and neuroinflammation. Thus, NMDAR targeting may constitute a captivating approach to rein in Japanese encephalitis

Microarray Analysis Identifies the Potential Role of Long Non-Coding RNA in Regulating Neuroinflammation during Japanese Encephalitis Virus Infection

Japanese encephalitis virus (JEV) is the leading cause of epidemic encephalitis worldwide. JEV-induced neuroinflammation is characterized by profound neuronal cells damage accompanied by activation of glial cells. Albeit long non-coding RNAs (lncRNAs) have been emerged as important regulatory RNAs with profound effects on various biological processes, it is unknown how lncRNAs regulate JEV-induced inflammation. Here, using microarray approach, we identified 618 lncRNAs and 1,007 mRNAs differentially expressed in JEV-infected mice brain. The functional annotation analysis revealed that differentially regulated transcripts were predominantly involved in various signaling pathways related to host immune and inflammatory responses. The lncRNAs with their potential to regulate JEV-induced inflammatory response were identified by constructing the lncRNA-mRNA coexpression network. Furthermore, silencing of the two selected lncRNAs (E52329 and N54010) resulted in reducing the phosphorylation of JNK and MKK4, which are known to be involved during inflammatory response. Collectively, we first demonstrated the transcriptomic landscape of lncRNAs in mice brain infected with JEV and analyzed the coexpression network of differentially regulated lncRNAs and mRNAs during JEV infection. Our results provide a better understanding of the host response to JEV infection and suggest that the identified lncRNAs may be used as potential therapeutic targets for the management of Japanese encephalitis