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Photoluminescence（PL）imaging techniques and the minority carrier lifetime test system were employed to investigate the variation of the interstitial iron (Fei) concentration, the recombination activity of structural defects and the minority carrier lifetime of cast multicrystalline silicon (mc-Si) in response to the cooling rate after heating. The results showed that when the mc-Si wafers are heated to high-temperature (1000 °C) and then cooled to ambient temperature with different cooling rate, the Fei concentration, the number of recombination active dislocations and grain boundaries increased as the cooling rate rises while the minority carrier lifetime decreased. If cast mc-Si is heated followed by faster cooling at 30 °C/s, the Fei concentration increase by 223% and the electrical activity of grain boundaries, dislocations and intragrain increase significantly, that is to say, the whole wafer is heavily contaminated with metal impurities, and present extremely low minority carrier lifetime.

Cu(In,Ga)Se2 (CIGS) is a promising candidate to replace crystalline silicon solar cells and dominate the photovoltaic market in the future. Alkali elements such as sodium (Na), potassium (K), rubidium (Rb), and Cesium (Cs) are commonly accepted as indispensable parts to boost cell efficiencies of CIGS thin-film solar cells. Therefore, a comprehensive understanding of alkali effects on the electronic and chemical properties of the CIGS layer as well as the underlying mechanisms is of paramount importance for achieving high-performance solar cells. This paper reviews the development process and incorporation pathways of alkalis and then overviews the roles of different alkali elements and their effects on CIGS cells in detail. Furthermore, the unsolved problems and future development prospects are also proposed. Overall, the understanding and development of widely adopted alkali-fluoride post-deposition treatments (PDTs) are still underway, and together with newly updated research, it will likely enable the CIGS technology to make the conversion efficiency closer to its theoretical limit.

Amorphous and crystalline SiC nanoparticles were synthesized via laser ablation of SiC micro-sized powder in water and ethanol. X-ray and HRTM analysis showed the amorphous nature of SiC nanoparticles with an average particle size of 44 nm in water and crystalline 6H-SiC polytype nanoparticles with an average size of 18 nm in ethanol. The direct and indirect bandgap of SiC nanoparticles were determined from UV–visible absorption spectra. PL emission characteristics were studied and crystalline SiC nanoparticles exhibit tunable PL emission covering UV to the visible region.

Crystalline silicon (c-Si) solar cells using interdigitated back contact (IBC) configurations are one of the most promising candidates to reach the practical efficiency limits of c-Si solar cells. However, the complexity of the process flow hinders the mass production of the IBC cells with conventional doped regions. One of the simple fabrication methods is to introduce the dopant-free carrier-selective contacts, which utilizes the fabrication processes with low temperature, e.g., the thermal evaporation or the spin coating. In this paper, we investigated efficiency close to 20% silicon IBC solar cells with dopant-free asymmetric hetero-contacts. In this solar cell configuration, the high work function material MoOx was chosen as the hole transporting layer, while the low work function material LiF was chosen as the electron transporting layer, respectively. The simulation results indicate that the perspective efficiency exceeding 22% for this type of cells is achievable with the optimized pitch width and improved passivation quality of the contacts, which has a great potential for the industrialization of IBC solar cells with simple fabrication processes.

The main contribution of this paper is proposing a new approach for retrieving the five parameters of the single diode equivalent model (SDM) of photovoltaic cells/modules including the series and shunt resistances. The least square method is used as an error minimization technique for fitting the non-linear transcendental model equation of the solar panel to the measured I–V characteristics. Newton Raphson method is applied to solve the system of five non-linear equations which represent the error of each parameter. Initial guess values are calculated with an optimised algorithm depending on information extracted from the same measured data. MATLAB programming script was used in all implementation steps. This approach is useful for a wide variety of applications where the five SDM parameters have to be determined from the measured curves, particularly, for self-fabricated cells/modules or in case of no available datasheet. One of the strengths of this method is the higher level of accuracy because of the absence of mathematical simplifications and physical assumptions. The method was validated on different types of PV devices, including a crystalline silicon cell, a polycrystalline module, and an amorphous module by using measurement data obtained at a wide range of solar irradiance conditions and temperatures.

The potential induced degradation (PID) phenomenon of p-type c-Si photovoltaic technology is a severe degradation mode that caught the attention of researchers since it can significantly affect the energy production of the PV plants. Various modeling/lab-tests have been conducted but very few are the in-situ experiments estimating the behavior of PID under real operating conditions on desert climate. In this context, the present work inspects the PID presence in an operational PV plant of a p-type monocrystalline silicon (mono-Si) technology with a capacity of 22,2-kW, installed in a Bsh (Hot semi-arid) climate. Besides, the assessment of the PID's impact on the affected modules have been measured and evaluated using several inspection techniques; electroluminescence (EL), thermography (IR) and I–V curve. Furthermore, we have evaluated the PID recovery process in the affected PV modules, and its first appearance in non-affected modules using a polarity inversion technique. The key finding shows that PID can be considered a significant degradation mode affecting the durability and the power output of crystalline silicon modules. Furthermore, the bias polarity change (to only demonstrate that the PID can be regenerated) can recover the PID causing power losses after a very short period. The results of this study demonstrate that PID can rapidly occur within three months in a semi-arid climate of Morocco.

A multicrystalline silicon solar cell was analyzed using Raman microspectroscopy. We measured the prominent Raman modes of silicon, nanocrystalline silicon and silver oxide in various regions of the solar cell to generate insights into the process and material quality of the finished device. First, by comparing the distribution of the transverse optical (TO) phonon peak position and full-width-at-half-maximum (FWHM) of the solar cell with a single crystal silicon wafer, the quality of the multicrystalline silicon surface was ascertained. Second, a similar analysis of the remnant saw marks on the device surface showed a discernably higher and wider distribution of TO phonon peak position and FWHM compared to a multicrystalline silicon surface. This indicated the presence of residual compressive stresses in the saw mark region. Third, by observing the silver fingers and bus bars, a residual silver oxide layer was identified, up to 25 μm away from the line edges. This was attributed to the screen printing of the silver paste and the subsequent firing process. Finally, Raman mapping on an embedded inclusion showed the presence of nanocrystalline silicon phase. The multicrystalline silicon region surrounding the inclusion was under tensile stress. A nondestructive, confocal Raman analysis of the inclusion provided a 3-D visualization of the defect, both inside and above the surface of the multicrystalline silicon wafer.

The role of Photovoltaic technologies integrated or attached to the building envelope is crucial in managing the building energy demand. In this paper, the performance of PV technologies with the mounting methods of Building integrated and Free-standing (Building attached) is discussed for six different climate zone of the country. A PVGIS program proposed with three PV cell technologies (Crystalline Silicon, Copper indium diselenide, Cadmium Telluride) is used to evaluate monthly energy generation potential and losses of the 2 kWp grid-connected PV system at the latitude and 90°. A 2 kWp PV system is chosen for Economic Weaker Section (EWS) housing schemes depending upon the roof area. From the evaluation, the performance parameter has been estimated. A new parameter Energy Deviation (ED), is proposed to choose the best PV technology in terms of performance. The results of ED agree with the parameters Performance Ratio (PR) and Capacity Factor (CF) defined under the IEC Standard 61724. The potential generation of PV technologies at 90° varies from 41% (Warm and Humid) to 64% (Cold and Sunny) when compared with the latitude. In case of Cold and Sunny and Cold and Cloudy at 90°, the generation performance of Copper indium diselenide is found better in Building integrated and Free-standing mounting methods, respectively. For the remaining zones, Cadmium Telluride technology shows better results. The Percentage loss in the system is found to be minimum in the case of Cold and Sunny, varies between 17% and 25%, and maximum is found for Warm and Humid and varies between 23.2% and 33.4% for the proposed PV technologies. The grid feed-in energy from these EWS houses for all the technologies and climatic zones is found above 45%. It is seen that the combined energy generation from the envelopes (Roof, walls, and facades) makes the houses energy plus in nature. The study has important implications for the government to promote the building integrated Photovoltaic policies in the country.

We present a comprehensive comparative analysis of acid textured and MACE (Metal Assisted Chemical Etching) nano-textured multi crystalline silicon (mc-Si) solar cells processed in an industrial cell line in terms of performance parameters. The batch average open circuit voltage of nano-textured solar cells was marginally lower and the measures for improving the same are discussed. Batch average short circuit current (J S C ) and fill factor (FF) were respectively 0.65 mA-cm−2 and 0.7% (absolute) higher for MACE nano-textured solar cells. Significantly lower surface reflectance in MACE nano-textured cells in the blue and near infrared regions are found to be the reason for the enhancement in J S C . The main component of FF gain is identified as the lower series resistance in MACE cells. The contact formation mechanism in screen printed mc-Si solar cells, investigated using scanning electron microscopy, revealed that the elevated portions at the boundaries of the textures act as favorable sites for silver crystallite precipitation. A larger areal density of such sites is observed on the MACE nano-textured surface than in case of acid textured solar cells, leading to a much lower series resistance. The results suggest the potential for the application of MACE in the more popular mono-crystalline silicon cell technology for further reduction of contact resistance. Alternatively, MACE may be used to obtain similar contact resistance with lower amount of silver paste, compared to iso- and pyramid textured solar cells.

Summary Stacking perovskite solar cells onto crystalline silicon bottom cells in a monolithic tandem configuration enables power-conversion efficiencies (PCEs) well above those of their single-junction counterparts. However, state-of-the-art wide-band-gap perovskite films suffer from phase stability issues. Here, we show how carbazole as an additive to the perovskite precursor solution can not only reduce nonradiative recombination losses but, perhaps more importantly, also can suppress phase segregation under exposure to moisture and light illumination. This enables a stabilized PCE of 28.6% (independently certified at 28.2%) for a monolithic perovskite/silicon tandem solar cell over ∼1 cm2 and 27.1% over 3.8 cm2, built from a textured silicon heterojunction solar cell. The modified tandem devices retain ∼93% of their performance over 43 days in a hot and humid outdoor environment of almost 100% relative humidity over 250 h under continuous 1-sun illumination and about 87% during a 85/85 damp-heat test for 500 h, demonstrating the improved phase stability.

Perovskite/Silicon (PS) tandem solar cells have attracted much interest over recent years. However, the most popular crystalline silicon solar cells utilized in tandems require complicated fabrication processes mainly including texturization, diffusion, passivation and metallization, which takes up much cost in photovoltaic market. Here, we report a facile graphene/silicon (Gr/Si) solar cell featuring of low-temperature (≤ 200 ℃) processing and an efficiency of 13.56%. For reducing the heat dissipation loss of high energy photon, the perovskite solar cell (PSC) with a wide band gap of 1.76 eV was adopted as the top cell for the tandem. To reduce the loss of parasitic absorption in hole transport layers (HTLs), thickness of Spiro-OMeTAD is re-optimized by compromising the efficiency and the optical transmittance of the devices. As a result, the semitransparent top perovskite solar cell yields a highest efficiency of 13.35%. Furthermore, we firstly achieved a low-temperature-processed four-terminal (4-T) perovskite/graphene-silicon (PGS) heterojunction tandem solar cell with the efficiency of 20.37%. The levelized cost of electricity (LCOE) of PGS 4-T modules were estimated to a competitive price, exhibiting much greater potential for practical application compared to that of PS 4-T modules.

The heterojunction (HJ) solar cell is one of the best possible options to upgrade the conventional single homo-junction c-Si solar cell. In this work, a single HJ solar cell based on crystalline silicon (c-Si) wafer with zinc oxide (ZnO) is designed to reduce the loss of power conversion owing to the reflection of incident photons by the top surface of silicon. A PC1D simulation is used to evaluate the optimum numerical value of key photovoltaic parameters for HJ-based c-Si solar cells. The average reflectance for ZnO/Si HJ-based c-Si is 7.65% in the wavelength range of 400-1000 nm. The highest efficiency (η = 24.8%) of the ZnO/Si HJ-based c-Si solar is obtained with a 400 μm base thickness, 20 μm emitter thickness, doping concentration of 1.1 × 1017 cm−3 in the base and a doping concentration of 5.1 x 1016 cm−3 in the emitter. The proposed ZnO/Si HJ-based c-Si solar cell with high efficiency would be one of the best possible alternative HJ device to the conventional single homo-junction c-Si solar cell.

Objectives of the work are to understand the challenges related to the technical performance and reliability of crystalline silicon solar cells in hot desert climates, where heat and high UV experienced in the region pose a challenge for the optimal performance. A comprehensive analysis on performance degradation and failure modes of c-Si modules in Algeria desert climate was carried out. Several modules were tested using an IV tracer and visual inspection. The modules have been in the field for considerable time (6 to 11 years). Results revealed some defects, such as; physical material defects, decreasing in the cell shunt resistance and increase in the cell series resistance that have mainly contributed in drop of output power. The hot desert climates affect the performance and lifetime of silicon solar cells negatively. This study is important for accurate prediction of performance, degradation, fatigue failure and reliability of PV panels, especially for PV installation in particular geographic regions as hot climatic zones.

Objectives. This paper presents data on the development and study of the structural properties of iron-doped crystalline silicon (nc-Si/SiOx/Fe) nanoparticles obtained using the plasma-chemical method for application in magnetic resonance imaging diagnostics and treatment of oncological diseases. This work aimed to use a variety of analytical methods to study the structural properties of nc-Si/SiOx/Fe and their colloidal stabilization with citrate anions for in vivo applications.Methods. Silicon nanoparticles obtained via the plasma-chemical synthesis method were characterized by laser spark emission spectroscopy, atomic emission spectroscopy, Fouriertransform infrared spectroscopy, and X-ray photoelectron spectroscopy. The hydrodynamic diameter of the nanoparticles was estimated using dynamic light scattering. The toxicity of the nanoparticles was investigated using a colorimetric MTT test for the cell metabolic activity. Elemental iron with different Fe/Si atomic ratios was added to the feedstock during loading.Results. The particles were shown to have a large silicon core covered by a relatively thin layer of intermediate oxides (interface) and an amorphous oxide shell, which is silicon oxide with different oxidation states SiOx (0 ≤ x ≤ 2). The samples had an iron content of 0.8–1.8 at %. Colloidal solutions of the nanoparticles stabilized by citrate anions were obtained and characterized. According to the analysis of the cytotoxicity of the modified nanosilicon particles using monoclonal K562 human erythroleukemia cells, no toxicity was found for cells in culture at particle concentrations of up to 5 µg/mL.Conclusions. Since the obtained modified particles are nontoxic, they can be used in in vivo theranostic applications.

Bilirubin (BR) is a product of hemoglobin breakdown, and its increasing levels in the blood may indicate liver disorders and lead to jaundice. Kernicterus is most dangerous in newborns when the unconjugated BR concentration can quickly rise to toxic levels, causing neurological damage and even death. The development of an accurate, fast, and sensitive sensor for BR detection will help reduce diagnostic time and ensure successful treatment. In this study, we propose a new method for creating a surface-enhanced Raman scattering (SERS)-active substrate based on gold-decorated silicon nanowires (Au@SiNWs) for sensitive label-free BR detection. Gold-assisted chemical etching of crystalline silicon wafers was used to synthesize SiNWs, the tops of which were then additionally decorated with gold nanoparticles. The low detection limit of model analyte 4-mercaptopyridine down to the concentration of 10-8 M demonstrated the excellent sensitivity of the obtained substrates for SERS application. The theoretical full-wave electromagnetic simulations of Raman scattering in the Au@SiNW substrates showed that the major contribution to the total SERS signal comes from the analyte molecules located on the SiNW surface near the gold nanoparticles. Therefore, for efficient BR adsorption and SERS detection, the surface of the SiNWs was modified with amino groups. Label-free detection of BR using amino modified Au@SiNWs with high point-to-point, scan-to-scan, and batch-to-batch reproducibility with a detection limit of 10-6 M has been demonstrated. Artificial urine, mimicking human urine samples, was used as the matrix to get insights into the influence of different parameters such as matrix complexity on the overall BR SERS signal. The signal stability was demonstrated for 7 days after adsorption of BR with a concentration of 5 × 10-5 M, which is the required sensitivity for clinical applications.

Sensitizing crystalline silicon (c-Si) with an infrared-sensitive material, such as lead sulfide (PbS) colloidal quantum dots (CQDs), provides a straightforward strategy for enhancing the infrared-light sensitivity of a Si-based photodetector. However, it remains challenging to construct a high-efficiency photodetector based upon a Si:CQD heterojunction. Herein, we demonstrate that Si surface passivation is crucial for building a high-performance Si:CQD heterojunction photodetector. We have studied one-step methyl iodine (CH3I) and two-step chlorination/methylation processes for Si surface passivation. Transient photocurrent (TPC) and transient photovoltage (TPV) decay measurements reveal that the two-step passivated Si:CQD interface exhibits fewer trap states and decreased recombination rates. These passivated substrates were incorporated into prototype Si:CQD infrared photodiodes, and the best performance photodiode based upon the two-step passivation shows an external quantum efficiency (EQE) of 31% at 1280 nm, which represents a near 2-fold increase over the standard device based upon the one-step CH3I passivated Si.

Porous silicon (PS) is a material with a great interest due to its optical (photoluminescent) and chemical (reactive surface) properties, for this reason, it is important to find new ways to be applied in the development of new devices. In this work the optic, chemical and morphologic properties of PS compressed into a tablet were characterized. The porous silicon was physically removed from the crystalline silicon and then was compressed to obtain a tablet. The optical characterization was performed through photoluminescence (PL) spectra. The PL spectrum from the PS tablet showed a small shift to higher wavelengths in comparison with the PS layers used to obtain the tablet. The x-ray diffraction pattern showed a loss in PS tablet crystallinity after being subjected to the compression process. The morphological characterization was carried out with a scanning electron microscope and the images showed a compact surface with high rugosity. This result was supported by the profilometry analysis, which also showed an irregular surface. The chemical properties of the surface were characterized with Fourier transform infrared spectroscopy (FTIR). The FTIR characterization showed an oxidized and highly hydrogenated surface.

Solar power generation plays an increasingly important role in the context of the energy revolution. Apart from the widely used crystalline silicon photovoltaic (c-Si PV) cells and flat plate vacuum solar thermal collectors for decentralized energy generation, concentrating solar power systems are on the rise due to their ability to reach high process temperatures and/or high photovoltaic (PV) efficiencies. In order to push technological advancements in this field, high-flux solar simulators are required for development and testing of components and modules under reproducible conditions. This paper describes the design process, manufacturing and commissioning of a versatile, low-cost, high-flux solar simulator for the investigation of concentrator photovoltaic (CPV) cells or other parts and modules used in concentrating solar systems. The design and development process of the solar simulator is described in detail, starting with the compilation of the requirement list, followed by the selection of the correct light source, all the way to the measurement technology and graphic user interface. The solar simulator is also characterized based on IEC and ASTM standards regarding spectral mismatch, concentration factor, temporal stability, as well as adjustability for a variety of measurement tasks. It can reach adjustable concentration factors of more than 200 suns in an area of 50 x 50 mm and the cost was kept below 5000 €. Finally, exemplary test results of an Azurspace 3C44 multi-junction cell under different concentration factors are presented.

A low-cost and easy-available silicon (Si) feedstock is of great significance for developing high-performance lithium-ion battery (LIB) anode materials. Herein, we employ waste crystalline Si solar panels as silicon raw materials, and transform micro-sized Si (m-Si) into porous Si (p-Si) by an alloying/dealloying approach in molten salt where Li+ was first reduced and simultaneously alloyed with m-Si to generate Li-Si alloy at the cathode. Subsequently, the as-prepared Li-Si alloy served as the anode in the same molten salt to release Li+ into the molten salt, resulting in the production of p-Si by taking advantage of the volume expansion/contraction effect. In the whole process, Li+ was shuttled between the electrodes in molten LiCl-KCl, without consuming Li salt. The obtained p-Si was applied as an anode in a half-type LIBs that delivered a capacity of 2427.7 mAh g−1 at 1 A g−1 after 200 cycles with a capacity retention rate of 91.5% (1383.3 mAh g−1 after 500 cycles). Overall, this work offers a straightforward way to convent waste Si panels to high-performance Si anodes for LIBs, giving retired Si a second life and alleviating greenhouse gas emissions caused by Si production.

Solar cells based on thin crystalline silicon (c-Si) substrates have the potential to provide relevant efficiencies with less material. In this article, we report on the fabrication of thin solar cells starting from a 20 μ m-thick c-Si wafer. Special attention is paid to optical performance of the rear surface where we need very high internal reflection and light scattering to improve light trapping properties of the device. In this sense, we introduce a texturization of the rear surface, which is excellently passivated by aluminium oxide films. In addition, for the rear contacts we use metal-covered wide-bandgap materials to improve back reflectance with a Vanadium Oxide/c-Si heterojunction for the emitter regions while the base contacts are defined by laser processing phosphorus doped amorphous silicon carbide films. Best solar cell has a reasonable efficiency of 8.7% and, more importantly, external quantum efficiency measurements demonstrate a better performance for photons with λ > 900 nm than in the case of a flat rear surface.

The differential cross section values of the natSi(p,p0) elastic scattering were determined in the energy range of Ep,lab = 3000–5000 keV at 6 backscattering detection angles (120°, 130°, 140°, 1 50°, 160° and 170°). The target was a self-supported thin Si3N4 foil. In addition, a thick crystalline silicon wafer was irradiated on its unpolished side with protons at energies Ep,lab = 3200, 3400, 3600, 3850, 4100, 4300, 4500, 4740, 5000 keV, in order to validate the results of the first experiment. On top of both targets a thin layer of 197Au was evaporated for normalization purposes. Both measurements were performed in parallel, using the 5.5 MV TN11 HV Tandem Accelerator and the high precision goniometer of N.C.S.R. ‘Demokritos’, Athens, Greece. The experimental and data analysis processes are presented in detail, as well as, comparisons between the obtained differential cross sections and already existing datasets in literature, along with the benchmarking results.

The performance of photovoltaic modules is highly dependent on the properties of the materials used to build them and is particularly sensitive to the type of encapsulant in the case of harsh outdoor environments. In this study, we compared the effects of ultraviolet (UV) radiation, under laboratory accelerated aging conditions, of four encapsulants: thermoplastic olefin, thermoplastic polyurethane, silicone, and ethylene vinyl acetate. The operation of the indoor ultraviolet chamber, using a mercury/xenon arc lamp as a radiation source, was related to the Atacama Desert ultraviolet conditions to estimate the corresponding time under outdoor conditions. The total indoor experiment time corresponded to 24.7 years of UV-B and 1.34 years UV-A irradiation. Transmittance in the ultraviolet–visible range, together with Raman spectra were analyzed to assess the effect of ultraviolet degradation. The aged encapsulants showed a transmittance reduction between 2% and 5% and a displacement in the ultraviolet cut off to higher wavelengths of around 5 nm. This information was used to compute the potential effect on the photogenerated current density of crystalline silicon photovoltaic modules, which decreased between 1% and 4%. Raman spectroscopy indicated the degradation of the encapsulants’ polymer structure as an increment in the fluorescence of the spectra, above 50%, and modifications in the relative intensities of the encapsulants active Raman modes.

This study identifies unstable and soluble layers in commercial photovoltaic modules during 1.5 year long-term leaching. Our experiments cover modules from all major photovoltaic technologies containing solar cells from crystalline silicon (c-Si), amorphous silicon (a-Si), cadmium telluride (CdTe), and copper indium gallium diselenide (CIGS). These technologies cover more than 99.9% of the world market. We cut out module pieces of 5 &times, 5 cm2 in size from these modules and leached them in water-based solutions with pH 4, pH 7, and pH 11, in order to simulate different environmental conditions. Unstable layers open penetration paths for water-based solutions, finally, the leaching results in delamination. In CdTe containing module pieces, the CdTe itself and the back contact are unstable and highly soluble. In CIGS containing module pieces, all of the module layers are more or less soluble. In the case of c-Si module pieces, the cells&rsquo, aluminum back contact is unstable. Module pieces from a-Si technology also show a soluble back contact. Long-term leaching leads to delamination in all kinds of module pieces, delamination depends strongly on the pH value of the solutions. For low pH-values, the time dependent leaching is well described by an exponential saturation behavior and a leaching time constant. The time constant depends on the pH, as well as on accelerating conditions such as increased temperature and/or agitation. Our long-term experiments clearly demonstrate that it is possible to leach out all, or at least a large amount, of the (toxic) elements from the photovoltaic modules. It is therefore not sufficient to carry out experiments just over 24 h and to conclude on the stability and environmental impact of photovoltaic modules.

Recent research in the field of photovoltaic and solar cell fabrication has shown the potential to significantly enhance light absorption in thin-film solar cells by using surface texturing and nanostructure coating techniques. In this paper, for the first time, we propose a new method for nano sandwich type thin-film solar cell fabrication by combining the laser amorphization (2nd solar cell generation) and laser nanofibers generation (3rd solar cell generation) techniques. In this novel technique, the crystalline silicon is irradiated by megahertz frequency femtosecond laser pulses under ambient conditions and the multi-layer of amorphorized silicon and nano fibrous layer are generated in the single-step on top of the silicon substrate. Light spectroscopy results show significant enhancement of light absorption in the generated multi layers solar cells (Silicon Oxide nanofibers / thin-film amorphorized silicon). This method is single step and no additional materials are added and both layers of the amorphorized thinfilm silicon and three-dimensional (3D) silicon oxide nanofibrous structures are grown on top of the silicon substrate after laser irradiation. Finally, we suggest how to maximize the light trapping and optical absorption of the generated nanofibers/thin-film cells by optimizing the laser pulse duration.

A comprehensive understanding of failure modes of solar photovoltaic (PV) modules is key to extending their operational lifetime in the field. In this review, first, specific failure modes associated with mature PV technologies, such as crystalline silicon (c-Si), copper indium gallium selenide (CIGS) and cadmium telluride (CdTe), are framed by sources of specific failure modes, their development from the early-developmental stages onwards and their impact upon long term performance of PV modules. These failure modes are sorted by both PV technology and location of occurrence in PV modules, such as substrate, encapsulant, front and rear electrode, absorber and interlayers. The second part of the review is focused on emerging PV technologies, such as perovskites solar cells, dye sensitised and organic PVs, where due to their low to medium technology readiness levels, specific long-term degradation mechanisms have not fully emerged, and most mechanisms are only partially understood. However, an in-depth summary of the known stability challenges associated with each emerging PV technology is presented. Finally, in this paper, lessons learned from mature PV technologies are reviewed, and considerations are given in to how these might be applied to the further development of emerging technologies. Namely, any emerging PV technology must eventually pass industry-standard qualification tests, while warranties for the lifetime of modern c-Si-based modules might be extended beyond the existing warranted life of 25 years.

Light management via photonic nanostructured coatings sustains a broad set of possible solar energy conversion enhancements, alternatively to conventional texturing processes that deteriorate solar cells (SCs) electrical transport through charge carrier recombination losses. These coatings, composed of high-refractive index materials structured at the sunlight wavelengths scale, can improve SCs efficiency, avoiding surface texturing processes while still allowing high-performance light trapping (LT). Here, through a highly scalable colloidal lithography methodology, proposed titanium dioxide (TiO2) nanovoid coatings were patterned on conventional (250 μm) and thin (90 μm) flat crystalline silicon (c-Si) wafers. These nanostructured coatings were also applied on textured (130 μm c-Si absorber), etched (140 μm) and flat (740 μm) c-Si interdigitated back contact solar cells (IBCSCs). The subsequent broadband absorption amplification was owing to the combined effects of (1) light scattering in near-infrared (NIR) wavelengths and (2) broad anti-reflection. With coated 250 μm c-Si wafers, a photocurrent density (𝐽𝑝ℎ) of 36.6 mA/cm2 was determined by absorption spectrum integration between 350 and 1200 nm. Approximately 84 % of the maximum theoretical 𝐽𝑝ℎ Lambertian LT limit is here attained with 669 and 693 nm of TiO2 thin photonic nanostructured coatings, respectively with the considered conventional and thin c-Si wafers. When integrated into test devices, outstanding optical improvements are attained without diminishing the original electrical performance by applying coatings with TiO2 thicknesses ≥ 545 nm. Unprecedent ~30 % of efficiency enhancement and 31.9 mA/cm2 of short-circuit current density (𝐽𝑠𝑐) are demonstrated with etched IBCSCs coated with 885 nm of TiO2 nanostructured coating. Additionally, unmatched optical angular acceptance is shown: 63 % of efficiency and 68 % of 𝐽𝑠𝑐 enhancements are respectively exhibited with 545 and 885 nm of TiO2 coatings for 80° of light incidence angle. Hence, with straightforward near-future integration in the established industry, a highly promising path for c-Si photovoltaic improvement is entailed. A gestão de luz mediante o uso de revestimentos nanoestruturados fotónicos sustenta um vasto leque de possíveis melhorias de conversão de energia solar, alternativamente a processos convencionais de texturização que deterioram o transporte eléctrico de células solares (CSs). Estes, compostos por materiais de elevado índice de refracção, podem elevar a eficiência de CSs, evitando texturizações enquanto possibilitam a captura de luz de elevado desempenho. Matrizes de nanocavidades de dióxido de titânio (TiO2) foram padronizadas por uma metodologia altamente escalável de litografia coloidal em bolachas de silício cristalino (c-Si) plano convencionais (250 μm) e finas (90 μm) e em CSs de contactos posteriores interdigitados (IBCSCs) texturizadas (130 μm c-Si), erodidas (140 μm) e planas (740 μm). A subsequente amplificação extensa da absorção deve-se à combinação dos seguintes efeitos: (1) dispersão de luz para comprimentos de onda do infravermelho próximo e (2) antirreflexão ampla. Com bolachas de c-Si convencionais, uma densidade de fotocorrente (𝐽𝑝ℎ) de 36.6 mA/cm2 determinada pela integração da absortância (350-1200 nm) foi conseguida. Aproximadamente 84 % do limite máximo teórico Lambertiano foi atingido com bolachas convencionais e finas revestidas com 792 e 693 nm de TiO2 nanoestruturado, respetivamente. Quando integrados em dispositivos de teste, a aplicação desses revestimentos com espessuras de TiO2 ≥ 545 nm conduziu a uma melhoria ótica substancial sem diminuir o desempenho elétrico original. Um aumento de ~30 % de eficiência e 31,9 mA/cm2 de densidade de corrente de curto-circuito (𝐽𝑠𝑐) são apresentados com IBCSCs revestidas com 885 nm de TiO2 nanoestruturado. É ainda demonstrada uma aceitação angular ótica incomparável: ganhos de 63 % de eficiência e 68 % de 𝐽𝑠𝑐, respetivamente com revestimentos de 545 e 885 nm de TiO2 nanoestruturado para um ângulo de luz incidente de 80°. Assim, com uma integração num futuro próximo na indústria, um caminho promissor para a evolução fotovoltaica em c-Si é implicado.