Crystalline Silicon Research Articles

Enhancing photovoltaic module sustainability: Defect analysis on partially repaired modules from Spanish PV plants

Between 2010 and 2022, there has been a significant increase in photovoltaic (PV) solar energy installations, driven by factors such as cost reductions, technological advances, policy support and innovative financing approaches. However, this rapid growth has created a significant challenge in the form of increased PV waste generation, coinciding with global commitments to achieve carbon neutrality by 2050. The potential for reuse of decommissioned PV modules represents an environmentally sustainable way forward that requires a comprehensive assessment of technical, economic, environmental and regulatory considerations. This study focuses on evaluating the impact of defects in partially repaired PV modules from Spanish installations on their power output and efficiency, with the aim of developing strategies to increase reuse and reduce environmental impact. The research focuses on 23 crystalline silicon modules and uses established techniques to evaluate their operational condition, detect defects and assess potential safety risks. Among the defects observed, moisture-induced degradation (MID) emerges as the most prevalent, followed by cracked cells and disconnected areas in cells across different technologies. Notably, despite the presence of defects, approximately 87 % of these modules have a power loss of less than 20 %.

Detailed modeling and numerical analysis of thermo mechanical stresses in the crystalline silicon and thin film PV modules under varying climatic conditions

The present manuscript provides an in-depth analysis of the modeling and simulation of thermo-mechanical stresses in photovoltaic panels using finite element (FEM) analysis. It covers important aspects such as the choice of the model, including governing equations, boundary conditions, and simplifying assumptions. The study mainly focuses on evaluating the impact of environmental conditions on the thermo-mechanical stresses of first-generation c-Si and second-generation thin-film CdTe and a-Si PV panels in five different climatic zones in Algeria. The proposed transient 3D numerical model is validated against experimental measurements by other researchers and the tabulated values of the nominal operating temperature of the cell (NOCT). The obtained results indicate that the first principle stress for the c-Si cell is lower compared to CdTe and a-Si cells; this can be explained by looking at the thickness, as well as the Young modulus of the solar cell. Consequently, in regions or countries with hot climatic conditions or large temperature gradients, it is recommended to use PV panels based on first-generation c-Si cells with glass-glass as the front and back covers.

The influence of temperature on spectral characteristics of silicon photovoltaic cells

The influence of temperature on spectral characteristics of silicon photovoltaic cells

Influence of inverted pyramid texturization on front metallization and performance of crystalline silicon solar cells

The silicon surface texturing is an essential part for the fabrication of crystalline silicon solar cells to increase the conversion efficiency. By adjusting the etching texturing condition, inverted pyramid (IP) and upright pyramid (UP) texturization were prepared on crystalline silicon substrates for fabrication of PERC solar cells. The surface morphology not only affects the light trapping but also impacts electrode shading loss and front electrode contact interface. The IP texturization presents better anti-reflective performance due to more common light paths and narrower silver grids owing to less flow of Ag paste on concave blocked structure, both of which results in the higher short-circuit current density (Jsc). Yet in terms of front Ag/Si contact interface, the IP texturization causes more Ag crystallites and more surface recombination under the present condition suitable for UP texturization because of more edges on the upper part of IP, which leads to the lower open-circuit voltage (Voc). The final conversion efficiency of IP solar cells (23.61 %) is 0.06 % higher than that of UP solar cells (23.55 %). An improvement about 0.07 mA/cm2 of Jsc was achieved with IP samples and Voc has a decrease of 0.3 mV caused by the surface recombination on IP texturization. In summary, the structural characteristics of IP results in lower reflectivity and less electrode shading, while Ag/Si contact interface could be optimized by adjusting the processing condition, ultimately promising the higher efficiency.

Crystalline Silicon Photocathode with Tapered Microwire Arrays Achieving a High Current Density of 41.7 mA cm⁻2

AbstractTo design a high‐efficiency crystalline silicon (c‐Si) photocathode, the photovoltage and photocurrent generated by the device must be maximized because these factors directly affect the hydrogen evolution reaction (HER). In this study, a c‐Si p–n junction is used to enhance the photovoltage of the c‐Si photocathode, and a tapered microwire array structure is introduced to increase the photocurrent. When tapered microwire arrays are employed on the front surface of the c‐Si photocathode, a current density of ≈41.7 mA cm−2 is achieved at 0 VRHE (reversible hydrogen electrode); this current density is the highest among all reported photocathodes including c‐Si, approaching the theoretical maximum value for c‐Si. Furthermore, a Ni foil/Pt catalyst is introduced on the opposite side of the incident light, simultaneously serving as an electrocatalyst to reduce side reactions in the HER and encapsulation layer to prevent c‐Si from contacting the electrolyte. Thus, a stable device is developed using c‐Si photoelectrochemical cells that have an efficiency exceeding 97% for >1000 h.

Theoretical Analysis and Simulation of SiO2 and ZrO2 Based Antireflective Coatings to Improve Crystalline Silicon Solar Cell Efficiency

The Solar cell efficiency is crucial, and optical losses can hinder it significantly. Anti-reflective coatings are effective in minimizing these losses. In our study, we used Fresnel equations to calculate reflectance values for single-layer SiO2, ZrO2, a SiO2-ZrO2 mixture, and a double-layer SiO2/ZrO2 configuration. We then assessed their impact on crystalline silicon solar cells using the SCAPS program. The reflectance values of single-layer SiO2, ZrO2 and 10%SiO2-90%ZrO2 mixture were calculated as 19.17%, 13.09% and 13.01%, respectively. Notably, the double-layer SiO2/ZrO2 coating showed a low reflectance of 7.58%, a significant improvement compared to uncoated silicon at 37.45%. Efficiency values for crystalline silicon solar cells were calculated for single layer as 18,95% (SiO2), 20.39% (ZrO2), 20,40% (mixed coating) respectively and 21.68% for the double-layer SiO2/ZrO2 configuration.

Free-standing ultrathin silicon wafers and solar cells through edges reinforcement

Crystalline silicon solar cells with regular rigidity characteristics dominate the photovoltaic market, while lightweight and flexible thin crystalline silicon solar cells with significant market potential have not yet been widely developed. This is mainly caused by the brittleness of silicon wafers and the lack of a solution that can well address the high breakage rate during thin solar cells fabrication. Here, we present a thin silicon with reinforced ring (TSRR) structure, which is successfully used to prepare free-standing 4.7-μm 4-inch silicon wafers. Experiments and simulations of mechanical properties for both TSRR and conventional thin silicon structures confirm the supporting role of reinforced ring, which can share stress throughout the solar cell preparation and thus suppressing breakage rate. Furthermore, with the help of TSRR structure, an efficiency of 20.33% (certified 20.05%) is achieved on 28-μm silicon solar cell with a breakage rate of ~0%. Combining the simulations of optoelectrical properties for TSRR solar cell, the results indicate high efficiency can be realized by TSRR structure with a suitable width of the ring. Finally, we prepare 50 ~ 60-μm textured 182 × 182 mm2 TSRR wafers and perform key manufacturing processes, confirming the industrial compatibility of the TSRR method.

Soft Lattice and Phase Stability of α‐FAPbI3

AbstractSince the certified power conversion efficiency (PCE) of perovskite solar cells (PSCs) has reached 26.1%, exactly equal to that of crystalline silicon solar cells, a strong demand for ensuring the long‐term stability of PSCs has arisen for commercialization. The intrinsic stability of the perovskite layer must be guaranteed as a top priority to ensure the whole device's stability. Recently, the state‐of‐the‐art PSCs, performing a high PCE, employ α‐FAPbI3 (FA = formamidinium) for the perovskite layer in spite of its metastable tendency to spontaneously transform into its photoinactive polymorph at PSC operating temperature. In this review paper, the intrinsic structural stability of α‐FAPbI3 soft lattice is understood from the thermodynamic point of view, with key parameters to restrain the undesirable phase transition. Besides, reported experimental results are closely examined to find fundamental origins, derive the enhanced phase stability in each experiment, and understand their role in maintaining the lattice structure from the collective perspective.

Material Innovations and Scalable Manufacturing for Next-Generation Advanced Organic Photovoltaics

Organic photovoltaics (OPVs), representing a novel paradigm in photoelectric conversion technologies, have garnered substantial interest within the renewable energy sector. These technologies, leveraging organic molecules or polymers for photon absorption and subsequent electricity generation, stand in contrast to traditional silicon-based solar cells. OPVs offer distinct advantages, including flexibility, lightweight construction, and cost-effective production, rendering them adaptable across diverse application contexts. Nonetheless, when juxtaposed with their silicon-based counterparts, the efficiency and longevity of OPVs remain areas necessitating further exploration and enhancement. Recent advancements have been achieved through meticulous material design, process refinement, and interface engineering, collectively contributing to the augmented efficiency and durability of OPVs. Looking ahead, it is anticipated that ongoing technological evolution and innovation will position organic solar cells and photovoltaics as pivotal components in the sustainable energy landscape, offering novel avenues to address the energy crisis and ameliorate the impacts of climate change.

Polarization and kinetics of optical emission during laser induced periodic surface structure formation on crystalline silicon

Polarization and kinetics of secondary optical emission, which occurs during the formation of laser-induced periodic surface structures (LIPSSs) on crystalline silicon by a femtosecond laser beam in air, were analyzed. It was found that the emission lines of ablated Si atoms and formed in plasma SiN molecules are unpolarized, and they decay on the nanosecond scale. The second harmonic generation (SHG) is enhanced by laser-induced surface plasmons, and the SHG polarization basically repeats the polarization of the laser. The results can be used for optical monitoring of LIPSS formation in real time, which is especially important for laser processing of large non-planar surfaces.

Anisotropy of the conductivity of silicon nanowires

ABSTRACT This study reports the findings from an investigation into charge carrier transport within a silicon nanowire layer. The samples were prepared using the metal-assisted chemical etching method applied to crystalline silicon wafers with a resistance of 10–20 Ω·cm. The resulting silicon nanowires had a diameter of about 100 nm with a resistance of approximately 15 kΩ·cm. Electrical conductivity measurements were performed in both planar and sandwich configurations, revealing analogous conductivity mechanisms across different geometries. Frequency-dependent conductivity studies unveiled the presence of hopping conductivity. A hypothesis is proposed regarding the existence of a potential barrier at the interface between the nanowire layer and the substrate.

High performance GaAs ultrathin film solar cell based on optimized antireflection coating and dielectric nano-cylinders

This study presents an ultrathin crystalline GaAs solar cell consists of titanium dioxide (TiO2) nano-cylinders partially embedded in the GaAs film and covered by a proper antireflection coating. For light trapping over the solar spectrum and consequently, enhancing the optical and electrical characteristics of the cell, the thickness and refractive index (RI) of the antireflection coating and the embedding depth of the nano-cylinders in the GaAs film have been optimized. Also, aluminum (Al) metallic layer is applied at the backside of the cell to obtain a higher absorption at longer wavelengths due to photon reflection into the GaAs film. In the suggested solar cell, improvements of 70.65 % and 78.12 % in the short current density (JSC) and the power conversion efficiency are obtained, respectively compared to the conventional GaAs solar cell (Case 1).

Effect of glass frit composition on reliability of silver paste metallization in crystalline silicon solar cells

Glass frit used in conductive silver (Ag) pastes has a significant impact not only on the electrical performance but also on the long-term reliability of metallized electrodes in crystalline silicon (c-Si) solar cells. Here, we investigated the role of compositional changes on the metallization process of silver pastes by adjusting the SiO2, ZnO, Li2O, or Bi2O3 in lead borate glass melts, and performed damp heat (DH) tests in an acidic damp heat environment. It was found that the addition of Bi2O3 resulted in a decrease in conversion efficiency (Eta) of only 6.44% after the cell was treated with dilute acetic acid. Under scanning electron microscopy (SEM), it was observed that the cell with this glass frit had minimal changes in the microstructure of its silver-silicon contacts and silver electrodes. This finding helps to improve the performance and stability of solar cells in harsh environments.

Bifacial silicon heterojunction solar cells using transparent‐conductive‐oxide‐ and dopant‐free electron‐selective contacts

AbstractThe development of transparent electron‐selective contacts for dopant‐free carrier‐selective crystalline silicon (c‐Si) heterojunction (SHJ) solar cells plays an important role in achieving high short‐circuit current density (JSC) and consequently high photoelectric conversion efficiencies (PCEs). This becomes even more important when focusing on the development of bifacial solar cells. In this study, bifacial SHJ solar cells using a transparent‐conductive‐oxide‐free and dopant‐free electron‐selective passivating contacts are developed, showing a JSC bifaciality of up to 97%. Intrinsic ZnOX layer deposited by atomic layer deposition was used in this structure, which simultaneously provides negligible passivation loss after annealing and enables a low contact resistivity on the electron‐selective contact. With both side finger metal electrodes contact, this bifacial solar cell shows an efficiency of 21.2% under front‐side irradiation and 20.4% under rear‐side irradiation, resulting in an estimated output power density of 24.1 mW/cm2 when considering rear‐side irradiance of 0.15 sun.

Interfacial energy-band engineering for high open-circuit voltage of rear emitter p-type crystalline silicon solar cells

Rear emitter p-type crystalline silicon (c-Si) tunnel oxide passivating contact (P-TOPCon) devices with low-resistivity (≤1 Ω.cm) c-Si wafer and high-conductivity phosphorus doped (n-type) polysilicon passivating contact (n-poly-Si PC) are expected to achieve high built-in potential (Vbi) and thus open-circuit voltage (Voc). However, the results indicate that the high conductivity of n-poly-Si PC considerably deteriorates the interface passivation quality and lowers the device's Voc. A crucial factor to consider is that the hole and electron can tunnel and recombine together at the c-Si/n-poly-Si PC contact, resulting in a decrease in the quality of interfacial passivation. To inhibit carrier tunnel diffusion and enable energy band engineering at the interface for achieving high Voc, a thin intrinsic poly-Si buffer layer (10 nm) is inserted between SiO2 and n-poly-Si PC. When compared to a device without a buffer, a device with the buffer exhibits a significant improvement in passivation quality and hence Voc. The device with buffer has a Voc of 705 mV and an efficiency of 23.5 %, while that without buffer is 681 mV and 22.6 %, respectively. The introduced buffer has little effect on the industrial manufacturing process, but it does significantly enhance Voc. It has the potential to improve the efficiency of the P-TOPCon devices.

Revolutionizing dye-sensitized solar cells with nanomaterials for enhanced photoelectric performance

Dye-sensitized solar cells have emerged as a promising alternative to conventional solar cells due to their cost-effectiveness and ease of fabrication. In recent years, the integration of nanomaterials into dye-sensitized solar cells has garnered substantial attention, offering new avenues to enhance their photoelectric performance. This review comprehensively examines the role of nanomaterials in elevating the efficiency and functionality of dye-sensitized solar cells. The fundamental principles of dye-sensitized solar cells are introduced, emphasizing the intricate interplay between crucial components that enable light absorption, charge separation, and electron transport. Nanomaterials play important roles across the entire spectrum of photoelectric conversion of dye-sensitized solar cells, e.g., constructing light-trapping architectures, creating interlayer transmission bridges, and facilitating charge carrier transport pathways, thus offering cost-effective alternatives to precious metals. Furthermore, this review concludes the central role of nanomaterials in shaping the landscape of flexible optoelectronic materials, highlighting their paramount importance in this area. The extensive scientific insights presented herein not only showcase the cutting-edge achievements in solar energy conversion efficiency but also serve as a comprehensive guide for the proper selection of nanomaterials. Finally, this work outlines the forthcoming challenges and offers insights into promising research avenues based on a comprehensive examination of various scholarly pursuits. Unlike other reviews that focus on the analyses of structures or components, this review concentrates on the impact of nanomaterials on the overall photoelectric performance of dye-sensitized solar cells. By fostering cross-disciplinary collaboration and advancing relevant research, dye-sensitized solar cells hold promise as a significant contributor to the global transition toward clean and renewable energy sources.

Dynamics of phase transformations in Si and Ge upon strong excitation with UV femtosecond laser pulses

Femtosecond laser processing of semiconductors has evolved into a mature, high-precision fabrication technique, enabling a wide range of applications. While initially most studies have employed pulses at near infrared wavelengths, the interest in using UV laser pulses is constantly increasing due to the different excitation conditions as a consequence of the much shorter optical penetration depth, leading to an improved resolution. In this context, fundamental studies on the temporal dynamics of phase transformations triggered by such pulses are necessary in order to comprehend and eventually control the complex phase transformation pathways. Here, we report a detailed time-resolved study on the phase transformation dynamics of crystalline silicon and germanium upon irradiation with single 400 nm, 100 fs laser pulses in the moderate and high excitation regime. To this end, we have employed fs-resolved optical microscopy with a probe wavelength of 800 nm to study the reflectivity evolution of the irradiated surface over a temporal window ranging from 100 fs up to 20 ns. At moderate excitation fluence, the data reveals the entire sequence of laser-induced processes, starting from the generation of a free-electron plasma, non-thermal melting, ablation onset and expansion of a semi-transparent ablation layer with sharp interfaces. At excitation with peak fluences more than 30 times the ablation threshold, an anomalous transient high-reflectivity state is observed, which might be indicative of a recoil pressure-induced liquid–liquid phase transition. Moreover, 70 nm-thick amorphous surface layers are formed in both materials after irradiation at moderate fluences. Overall, our results provide relevant information on both, transformation dynamics and final state of both materials for fs-pulse excitation in the near-UV wavelength range.

Exploiting green energy potential via FinTech: The role of DLT-based crowdfunding in PV and ESS investments

This article explores the interplay of green energy potential and innovative financial technology (FinTech). To achieve this, an in-depth study on the technological, economic, and environmental aspects of residential-scale solar energy and storage investments was performed. As the first part of the study, residential-scale solar energy and associated energy storage investments were modeled in the assessed countries. As the next step, the effects of Distributed Ledger Technology (DLT) enabled crowdfunding on the modeled investments were highlighted with a Proof-of-Concept (PoC) DLT-enabled investment tool. As the last step, the Life Cycle Assessments (LCAs) of the investments were carried out for each of the assessed countries in order to provide better investment decisions to various investors. The results of this research indicate that with the integration of novel Fintech tools, the Levelized Cost of Storage (LCOS) values of the assessed investments may be reduced by up to 58%. Meanwhile, the LCA results highlighted that solar silicon production and battery cell manufacturing have the highest LCA results, accounting for 19.1 and 63.8 kgCO2eq/kWh respectively. Meanwhile, the transportation sector had an emission of 9 kgCO2eq/kWh. Thus, with cleaner manufacturing and transportation, the emissions from PV and ESS investments may be reduced drastically.

Enhancing CsSn0.5Ge0.5I3 Perovskite Solar Cell Performance via Cu2O Hole Transport Layer Integration

Perovskite solar cells (PSCs) have emerged as a promising alternative to traditional silicon solar cells due to their low cost of fabrication and high power conversion efficiency (PCE). The utilization of lead halide perovskites as absorber layers in perovskite solar cells has been impeded by two major issues: lead poisoning and stability concerns. These hindrances have greatly impeded the industrialization of this cutting-edge technology. In light of the harmful effects of lead in perovskite solar cells, researchers have shifted their attention to exploring lead-free metal halide perovskites. However, the present alternatives to lead-based perovskite exhibit poor performance, thus prompting further inquiry into this matter. The primary objective of this research is to investigate the use of Cu2O as a hole transport layer in combination with lead-free metal halide perovskite (CsSn0.5Ge0.5I3) to achieve superior performance. Through meticulous experimentation, the suggested model has achieved outstanding results by optimizing several key variables. These variables include the thickness of the absorber layer (CsSn0.5Ge0.5I3), defect density, and doping densities, as well as the back contact work function and the operating temperature associated with each layer. The proposed FTO/PC60BM/CsSn0.5Ge0.5I3/Cu2O/Au solar cell structure surpassed prior configurations by comprehensively examining key aspects such as absorber layer thickness and defect density, doping densities, and back contact work. The structure has been also compared with multiple electron transport elements and concluded that the proposed model functions superior due to the use of PC60BM as an electron transport layer and it has an improved electron extraction procedure. Finally, the proposed model has achieved the optimized values as Jsc of 31.56 mA/cm-2, Voc of 1.12 V, FF of 81.47%, and PCE of 27.72%. As a consequence of this research, the investigated structure may be an excellent contender for the eventual creation of lead-free solar power cells made from perovskite.

浅析WTO 对《美国对进口晶体硅光伏产品的保障措施》的裁决

This article focuses on the safeguards measure case of “China vs. U.S. Crystalline Silicon Photovoltaic Products” and deeply explores the relevant issues related to safeguard measures in international trade remedies involved in this case. Research on this issue will help China better understand responding to related trade frictions in international trade has enabled China to change its passive position into an active position in dealing with such issues. This article explains the safeguard measure case of “China vs. United States Crystalline Silicon Photovoltaic Products” and then introduces the rules of the WTO safeguard measure system. It then analyzes the five focus points of dispute, focusing on the expert group’s analysis of the causal relationship in this case. Identify the situation, and finally discuss China’s response to such situations.