Bare Solar Cell Research Articles

Self-Healable Sandfish Scale-Inspired Scalable Triboelectric Layer for Hybrid Energy Harvesting in Desert Environment.

In deserts, sedimentation from frequent dust activities on solar cells poses a substantial technical challenge, reducing efficiency and necessitating advanced cost-inefficient cleaning mechanisms. Herein, a novel sandfish scale-inspired self-healing fluorinated copolymer-based triboelectric layer is directly incorporated on top of the polysilicon solar cell for sustained hybrid energy harvesting. The transparent biomimetic layer, with distinctive saw-tooth microstructured morphology, exhibits ultra-low sand adhesion and high abrasion-resistant properties, inhibits sedimentation deposition on solar cells, and concurrently harvests kinetic energy from wind-driven sand particles through triboelectric nanogenerator (TENG). The film exhibits a low friction coefficient (0.149), minimal sand adhesion force (27 nN), and a small wear area (327 µm2). In addition, over 2 months, a solar cell with the sandfish scale-inspired structure demonstrates only a 16% decline in maximum power output compared to the bare solar cell, which experiences a 60% decline. Further, the sandfish scale-based TENG device's electrical output is fully restored to its original value after a 6-h self-healing cycle and maintains consistent stable outputs. These results highlight the exceptional advantages of employing biomimetic self-healing materials as robust triboelectric layers, showcasing sustained device stability and durability for prolonged use in harsh desert environments, ultimately contributing to a low cost-of-electricity generation paradigm.

Deep learning-based method for defect detection in electroluminescent images of polycrystalline silicon solar cells

To achieve defect detection in bare polycrystalline silicon solar cells under electroluminescence (EL) conditions, we have proposed ASDD-Net, a deep learning algorithm evaluated offline on EL images. The model integrates strategies such as downsampling adjustment, feature fusion optimization, and detection head improvement. The ASDD-Net utilizes the Space to Depth (SPD) module to effectively extract edge and fine-grained information. The proposed Enhanced Cross-Stage Partial Network Fusion (EC2f) and Hybrid Attention CSP Net (HAC3) modules are placed at different positions to enhance feature extraction capability and improve feature fusion effects, thereby enhancing the model's ability to perceive defects of different sizes and shapes. Furthermore, placing the MobileViT_CA module before the second detection head balances global and local information perception, further enhancing the performance of the detection heads. The experimental results show that the ASDD-Net model achieves a mAP value of 88.81% on the publicly available PVEL-AD dataset, and the detection performance is better than the current SOTA model. The experimental results on the ELPV and NEU-DET datasets verify that the model has some generalization ability. Moreover, the proposed model achieves a processing frame rate of 69 frames per second, meeting the real-time defect detection requirements for solar cell surface defects.

Mediation of Interfacial Mo2C Bridging Effect in MoS2@Carbon Colloid Dots Featuring Improved Photovoltaic Performances of Si‐Based Hybrid Solar Cells

AbstractAdvances in silicon‐based hybrid solar cells with high photovoltaic performance, low synthetic cost, and sound environmental resistance are emerged as potential candidate for solar conversion. Solution‐processed few‐layer MoS2 sheets are regarded as compelling constitutes that paves ways for tailoring the solar harvesting capability; yet the improvement on charge separation of photoexcited carriers remains demanded, and the lack of environmental stability due to intentionally grabbing electrons from adsorbed moistures constrains the scope of practical assessment. In this work, the employment of MoS2/Mo2C/carbon colloid dots (CCDs) heterostructures within PEDOT:PSS matrix is invoked, where the transfer of photoexcited electrons from MoS2 is mediated with Mo2C electron‐transport channels, which further couple out the creation of positive trions by combining with defect‐bound excitons at CCD surfaces. These features dynamically involve with slow recombination probability and further improve the photovoltaic gain. Thus, the noticeable improvement of conversion efficiency of 16.1% with 1.6 times of efficiency enhancement outperforming the bare conventional hybrid solar cells is accomplished, and further exhibits a sound long‐term stability, which opens new avenues for exploiting the photophysical bound‐carrier transition on advanced photovoltaic applications.

UV/ visible/ NIR sensitized enhanced green luminescence of a newly synthesized salicylic acid coated Tb3+ and Yb3+ ions doped Y2O3 nano-composite phosphor: Prospect as luminescence solar collector material

The present work describes the enhancement of green luminescence of Tb3+ ion in a newly synthesized composite material that contains Tb3+ and Yb3+ ions in Y2O3 nano-phosphor (TYY) coated with salicylic acid (SA) doped polyvinyl alcohol (PVA) polymer matrix (TYY: SA/PVA). XRD results reflect nearly 50 nm size of crystallite in TYY phosphor. On coating, the same with SA-doped PVA polymer visualizes the actual particulate size in microns due to aggregation of nano-crystallites of TYY and indicates the formation of organic/inorganic composite material. In down-conversion of UV radiation, both singlet and triplet states of excited state intra-molecular proton transfer species of SA in TYY: SA/PVA composite material transfer their UV (200 nm–370 nm) excitation energy through Fӧrster and Dexter mechanism to 5D4 state of Tb3+ ions, which enhances green luminescence of Tb3+ ions [5D4 →7F5] by nineteen-fold and decrease in the NIR luminescence intensity of Yb3+ ion [2F5/2 → 2F7/2] in TYY/SA/PVA as compared to the TYY sample indicates coating of SA/PVA polymer on the nano phosphor blocks the quantum cutting process from 4f75 d1 excited state of Tb3+ ions to 2F5/2 state of Yb3+ ions. In contrast, TYY: SA/PVA and TYY material exhibit intense green luminescent emission of Tb3+ ions by up-conversion of NIR radiation through a cooperative energy transfer between two Yb3+ ions [2F5/2 → 5D4 excitation]. A thin layer coating of composite phosphor material shows enhancement in the external quantum efficiency of the solar cell by increasing the efficiency of ∼3–5 % in the 400 nm–1000 nm range compared to the bare solar cell. I–V characteristics of the composite show that simultaneous excitation of this composite material with UV/Visible/NIR radiation increases the photon density in blue, green, and NIR regions for reabsorption by the photovoltaic cell. This preliminary study signifies the scope for developing brighter, high photon flux luminescent composite luminescent solar collecter material with low cost.

Scalable Bacterial Cellulose-Based Radiative Cooling Materials with Switchable Transparency for Thermal Management and Enhanced Solar Energy Harvesting.

Radiative cooling materials that can dynamically control solar transmittance and emit thermal radiation into cold outer space are critical for smart thermal management and sustainable energy-efficient buildings. This work reports the judicious design and scalable fabrication of biosynthetic bacterial cellulose (BC)-based radiative cooling (Bio-RC) materials with switchable solar transmittance, which are developed by entangling silica microspheres with continuously secreted cellulose nanofibers during in situ cultivation. Theresulting film shows a high solar reflection (95.3%) that can be facilely switched between an opaque state and a transparent state upon wetting. Interestingly, the Bio-RC film exhibits a high mid-infrared emissivity (93.4%) and an average sub-ambient temperature drop of ≈3.7 °C at noon. When integrating with a commercially available semi-transparent solar cell, the switchable solar transmittance of Bio-RC film enables an enhancement of solar power conversion efficiency (opaque state: 0.92%, transparent state: 0.57%, bare solar cell: 0.33%). As a proof-of-concept illustration, an energy-efficient model house with its roof built with Bio-RC-integrated semi-transparent solar cell is demonstrated. This research can shine new light on the design and emerging applications of advanced radiative cooling materials.

Perovskite quantum dot-based tandem triboelectric-solar cell for boosting the efficiency and rain energy harvesting

Silicon (Si) solar cell efficiently convert solar energy into electricity under the sun illumination, but its inherent intermittent power generation due to diurnal and seasonal cycle has usually allowed for the requirement for alternative power sources. Owing to the abundance, diversity and availability, rain drop energy is one of the most promising green energy sources. Hence, hybrid energy harvesting could be a promising strategy of achieving preferential hybrid performances without sacrificing the advantages in individual devices. Herein, we proposed a hybrid solar and rain energy harvesting device featuring the integration of triboelectric nanogenerator (TENG) top-cell and a crystalline Si solar cell bottom-cell by laminating perovskite quantum dots-embedded polydimethylsiloxane composite film (PQDP) onto the Si solar cell, which endows enhanced electrical output performances under rainy days. To overcome the limitation of low external quantum efficiency (EQE) in the ultraviolet region of the Si solar cell, the PCE of the hybrid solar cell is significantly enhanced from 18.47% of bare Si solar cell to 20.16% owing to the anti-reflection effect of PQDP film and the down-conversion property of CsPbBr3 QDs doped with Ce3+ ions. Meanwhile, this hybrid solar cell presents excellent durability after continuous measurement over 7 days. This tandem hybrid solar cell provides a promising strategy to simultaneously scavenging the solar and rain energy and boosting the power conversion efficiency by introducing the perovskite QDs without affecting the efficiency of bare Si solar cell.

ZnO antireflection coating on solar cell to increase the efficiency by enhancing optical properties

In today's world, solar cell efficiency is an important concern. Anti-Reflection Coating serves a critical function in increasing solar cell efficiency. The efficiency of a solar cell is influenced by a variety of factors. The key issue here is reflectivity. Antireflection coatings are used to minimise the solar cell's reflectivity. AR coating is done using semiconductor materials. Generally, the reflectance of solar cells can be reduced up to 3.2% by using an Anti-reflection coating. In this experiment, ZnO is employed as an antireflection coating on the solar cell using the spin coating process. After coating, the solar cell is allowed to cure at a rapid rate of evaporation to get a thin film. UV-Spectrophotometer and Solar Simulator are used to investigate the coated solar cell's optical and electrical features. When the results are compared to the efficiency of a bare silicon solar cell, the coated cell outperforms the unprotected solar cell by 4%.

Particle‐induced degradation of III–V multi‐junction solar cells under different configurations of displacement damage dose

AbstractThe solar arrays of spacecrafts are subjected to a severe radiative environment. Associated degradation rates are dependent on operational orbit configuration. The current approach used in models and tools to determine power degradation shall thus be validated to ensure good prediction accuracy. This paper reports on extensive irradiation test campaigns realized on triple‐junction solar cells to compare degradation induced by different configurations of irradiation reproducing nominally the same displacement damage dose (DDD) in the active layer. These test campaigns data are used to support the validation of a new tool developed to optimize prediction accuracy of solar cell degradation. The DDD equivalence between front/rear irradiation on solar cell assemblies and on bare solar cells, between different electron and proton energies, as well as the verification of the superposition principle are addressed. Results are conclusive regarding the equivalence of degradation obtained with electrons, protons and/or combined electrons and protons, accounting for local shielding.

Study the influence of shell thickness in bimetallic Ag core&Au shell configurations integrated in bare Si PN junction solar cells

The effect of the gold layer thickness of Ag core&Au shell configurations on the performance of the bare Si n-type layer of a PN junction solar cell was explored. The different forms of Ag core&Au shell configurations were formed via pulsed laser ablation method of Ag and Au plate using second harmonic generation (SHG) of Nd:YAG laser wavelength at 530 nm with 0.61 J/cm2 energy flounce and various pluses repetition rate 350-500. The integrating of Ag core&Au shell configurations in n-type of bare PN Si junction was accomplished via pluses laser illumination of bare PN junction substrate. The photovoltaic results of formed solar cells showed strong dependence on Au shell thickness. Tangible enhancement was observed in the performance of bare Si solar cells after inserting core–shell configuration with specific shell thickness owning to the broadband absorption of plasmonics nanoparticles and the high values of specific surface area.

Improvement in the reliability of crystalline silicon solar cell interconnection by using Nickel Micro-Plating Bonding (NMPB) technology

It is popular to research promoting the light conversion efficiency of crystalline silicon solar cell photovoltaic (PV) modules. However, excellent light conversion efficiency does not mean it could maintain initial performance after long-term running. Long-term reliability of interconnection to assemble crystalline silicon solar cells in PV modules is critical to ensure that the device performs continually for up to 20 years. It is reported that most crystalline PV modules fail from corrosion and breakage of the interconnector with the solder joint. As a result, improvement of interconnection technology is highly necessary. Nickel (Ni) Micro-Plating Bonding (NMPB) is an innovative interconnection technology for crystalline silicon solar cells: copper ribbons bonded with lead or lead-free solder are replaced by copper wires bonded with Ni electroplating film. The NMPB interconnection provides key advantages: low temperature (55 °C) process, enhancement of reliability from strain and stress caused by high temperature, and coefficient of thermal expansion (CTE) mismatch between metal and silicon. Furthermore, the material of NMPB, Ni, possesses excellent corrosion resistance. High reliability was confirmed with about 1.9% degradation of output power for up to 1000 thermal cycling tests and 3.8% for 1000 h of damp heat tests in bare NMPB solar cells, while 64.7% degradation in thermal cycling tests and 23.0% in damp heat tests were confirmed in solder bonding solder cells.

Well-modifying the optical properties of bare Si solar cell by incorporating CuNPs

Well-modifying the optical properties of bare Si solar cell by incorporating CuNPs

GaAs thin-film solar cells photocurrent enhancement based on a new checkered grating back-reflector architecture

In this paper, a new back-reflector architecture has been investigated that can achieve a high short-circuit current density. For this, an ultra-thin film active layer of 150 nm GaAs is used, and the back-reflector structure is made of the checkered grating of Ag metal and photovoltaic material, i.e., GaAs. Hence, to decrease the initial reflection of the front surface of the cell and increase the optical path length, an anti-reflector layer is used. This checkered grating back-reflector structure by the scattering effect can reflect the unused photons into the photovoltaic layer, and these photons can travel a longer path in the photovoltaic layer, so have more chance to absorb. For proving of better performance of this structure, the simulation results are compared with a solar cell with flat BRS and the bare solar cell, that these two structures have the same volume of the photovoltaic layer as the main structure. The results of simulations show that the designed structure can achieve a short-circuit current density of 36.51 mA/cm2 and 28.04 mA/cm2, and conversion efficiency of 33.14% and 25.24%, respectively with and without the presence of anti-reflector coating.

The fabrication of anti-reflection grating structures film for solar cells using vibration-assisted UV nanoimprint lithography

To effectively improve the power conversion efficiency (PCE) of Si solar cells, vibration-assisted UV nanoimprint lithography based on piezoelectric driving is proposed to fabricate grating on Si solar cells. By applying piezoelectric vibration under the photoresist layer, vibration causes micro-displacement and micro-impact force, increasing the contact area between the photoresist and the grating's side wall and reducing surface tension. Meanwhile, the photoresist filling rate is increased by 25%. The effect of grating parameters on reflection is determined using Finite Difference Time Domain (FDTD), and grating with the best optical performance is optimized. In addition, the rationality of vibration introduction is verified by establishing a motion model, the influence of frequency and amplitude on the filling rate is analyzed using the finite element method, and a reasonable range of vibration parameters required by the experiment is obtained. Vibration-assisted UV nanoimprint is used to fabricate the periodic grating structures. PCE is increased by 25% when compared to bare Si solar cells. PCE of grating fabricated by vibration-assisted UV nanoimprint is increased by 4% when compared to traditional nanoimprint. The results show that vibration-assisted nanoimprint can efficiently and accurately fabricate periodic grating structures, resulting in improved Si solar cells performance.

Improvements in ultra‐light and flexible epitaxial lift‐off GaInP/GaAs/GaInAs solar cells for space applications

AbstractA thin, lightweight, flexible solar cell is developed that maximizes the power‐to‐mass ratio under AM0 illumination and has a competitive efficiency after typical high energy electron irradiation. The inverted metamorphic triple junction (IMM3J) solar cells with Ga0.51In0.49P/GaAs/Ga0.73In0.27As subcells are grown on GaAs substrates and have a total epitaxy thickness of about 10 μm. After epitaxial growth, the inverted layer stack is metallized, with the metal serving as back‐contact, back reflector and support layer for the ultra‐thin solar cells before the GaAs substrate is separated by an epitaxial lift‐off (ELO) process. The nondestructive nature of the ELO process makes multiple reuses of the GaAs substrate possible. The solar cell structure is optimized for maximum EOL efficiency, that is, after 1‐MeV electron irradiation with a fluence of 1 × 1015 cm−2, by means of simulations that include the irradiation induced defects in the various semiconductor alloys. Assuming realistic charge carrier lifetime in the materials, we predict a near‐term efficiency potential for the IMM3J ELO of 30.9% under AM0 illumination before and 26.7% after irradiation. Several IMM3J ELO solar cells with an area of approximately 20 cm2 from different development stages were tested under AM0 illumination. The newest solar cells (generation III) with a mass density of only 13.2 mg/cm2 reach conversion efficiencies of 30.2% at 25°C. The resulting power‐to‐mass ratio of 3.0 W/g for the bare solar cell is one of the highest published ratios. After irradiation, a conversion efficiency of 25.4% was measured for “generation II” devices under AM0 illumination, which corresponds to a power‐to‐mass ratio of 2.6 W/g. IMM3J ELO solar cells from “generation I” were also tested for mechanical stability as “de‐risking” test of this new cell technology. No degradation of the cell performance was found after dipping the cell in liquid N2 and then heating up to 25°C for five times, despite of strong deformation of the flexible cell during the temperature cycle.

Highly Efficient and Stable CsPbTh3 (Th = I, Br, Cl) Perovskite Solar Cells by Combinational Passivation Strategy.

The distorted lead iodide octahedra of all‐inorganic perovskite based on triple halide‐mixed CsPb(I2.85Br0.149Cl0.001) framework have made a tremendous breakthrough in its black phase stability and photovoltaic efficiency. However, their performance still suffers from severe ion migration, trap‐induced nonradiative recombination, and black phase instability due to lower tolerance factor and high total energy. Here, a combinational passivation strategy to suppress ion migration and reduce traps both on the surface and in the bulk of the CsPhTh3 perovskite film is developed, resulting in improved power conversion efficiency (PCE) to as high as 19.37%. The involvement of guanidinium (GA) into the CsPhTh3 perovskite bulk film and glycocyamine (GCA) passivation on the perovskite surface and grain boundary synergistically enlarge the tolerance factor and suppress the trap state density. In addition, the acetate anion as a nucleating agent significantly improves the thermodynamic stability of GA‐doped CsPbTh3 film through the slight distortion of PbI6 octahedra. The decreased nonradiative recombination loss translates to a high fill factor of 82.1% and open‐circuit voltage (V OC) of 1.17 V. Furthermore, bare CsPbTh3 perovskite solar cells without any encapsulation retain 80% of its initial PCE value after being stored for one month under ambient conditions.

Characterization of Plasmonic Scattering, Luminescent Down-Shifting, and Metal-Enhanced Fluorescence and Applications on Silicon Solar Cells.

This paper studied characterized the plasmonic effects of silver nanoparticles (Ag-NPs), the luminescent down-shifting of Eu-doped phosphor particles, and the metal-enhanced fluorescence (MEF) achieved by combining the two processes to enhance the conversion efficiency of silicon solar cells. We obtained measurements of photoluminescence (PL) and external quantum efficiency (EQE) at room temperature to determine whether the fluorescence emissions intensity of Eu-doped phosphor was enhanced or quenched by excitation induced via surface plasmon resonance (SPR). Overall, fluorescence intensity was enhanced when the fluorescence emission band was strongly coupled to the SPR band of Ag-NPs and the two particles were separated by a suitable distance. We observed a 1.125× increase in PL fluorescence intensity at a wavelength of 514 nm and a 7.05% improvement in EQE (from 57.96% to 62.05%) attributable to MEF effects. The combined effects led to a 26.02% increase in conversion efficiency (from 10.23% to 12.89%) in the cell with spacer/NPs/SOG-phosphors and a 22.09% increase (from 10.23% to 12.48%) in the cell with spacer/SOG-phosphors, compared to the bare solar cell. This corresponds to an impressive 0.85% increase in absolute efficiency (from 12.04% to 12.89%), compared to the cell with only spacer/SOG.

Ultraviolet-Filtering Luminescent Transparent Coatings for High-Performance PTB7-Th:ITIC–Based Organic Solar Cells

Photovoltaic (PV) devices based on organic heterojunctions have recently achieved remarkable power conversion efficiency (PCE) values. However, photodegradation is often a cause of dramatic drops in device performance. The use of ultraviolet (UV)-absorbing luminescent downshifting (LDS) layers can be a mitigation strategy to simultaneously filter UV radiation reaching the device and reemit it with lower energy in the visible spectral range, matching the maximum spectral response of the PV cells and thus enabling the increase of the photocurrent generated by the cell. In this work, we report the use of a Eu3+-doped siliceous-based organic–inorganic hybrid as a coating on organic solar cells based on the PTB7-Th:ITIC bulk heterojunction with the purpose of increasing their performance. We found that the applied coatings yield a PCE enhancement of ∼22% (from 3.1 to 3.8%) in solar cells with spin-coated layers, compared with the bare solar cells, which is among the highest performance enhancements induced by plastic luminescent coatings.

Broadband antireflection enhancement of c-Si solar cells by less 1/10 wavelength and subwavelength of silica nanosphere coatings

Monodisperse silica nanospheres with different diameters between 100 and 700 nm were fabricated using a slightly modified Stöber process. Silica nanosphere monolayers in a hexagonal array based on hydrophobically modification were well deposited on top of a bare crystalline silicon solar cell by a Langmuir-Blodgett method. The antireflection effect of various diameter silica nanospheres coatings was simulated using Comsol Multiphysics simulations. Silica nanosphere hexagonal array coatings with four kinds of diameters were fabricated based on results of simulations. The efficiency of solar cells covered by silica nanospheres has improved significantly with a maximum of 11.41% at 119 nm diameter while that of the planar solar cells was 10.17%, which is attributed to the improved photocurrents arising from the broadband antireflection and optical absorption. The antireflection effects produced by Rayleigh (<1/10 wavelength) and Mie scattering (subwavelength) of different diameters silica nanosphere structures were discussed in detail.

High symmetry nano-photonic quasi-crystals providing novel light management in silicon solar cells

Reduction of surface reflection loss is crucial for high efficiency next generation Si solar cells. Surface texturing provides a viable method to reduce loss over the full solar bandwidth. Previous studies have concentrated on simple moth-eye silicon pillar arrays protruding from the surface. Using FDTD simulation methods, we undertake a systematic investigation into performance benefits provided by complex semi-random photonic quasi-crystal surface patterning methodologies whereby arrays of air holes are etched deep into the solar cell surface. In contrast to other studies we carefully investigate the effect of lattice symmetry, systematically comparing performance of simple 6-fold symmetric triangular photonic crystal patterning to 12 fold symmetry photonic quasicrystal patterning and infinitely symmetric 2D Fibonacci patterning. We optimize key geometric parameters such as lattice pitch, hole size and etch depth to maximize optical performance for each lattice type. 12 fold photonic quasi crystal lattice is found to provide best overall anti-reflectance performance providing a solar-corrected average reflectance of 8.3% for a hole depth of 1.5 µm and 300 nm diameter, in comparison to 36.4% for a bare silicon solar cell surface. Practical feasibility of the optimal designs is demonstrated by fabrication of physical prototypes consisting of arrays of nm scale air-holes etched into the surface of a silicon slab fabricated Using e-beam lithography and ICP/RIE etching. FDTD Simulation methodology is validated by convergence studies as well as comparison to optical measurements on these fabricated devices. Furthermore, in contrast to previous studies we provide an in depth analysis of the physical mechanisms responsible for reduction in surface reflection, determining the parameter space where conventional Gaussian optical processes such as effective refractive index, refraction and Fresnel reflection dominate, vs parameter space where sub wavelength photonic crystal scattering effects play the main role. We finish up with an analysis of electrical performance for the optimal designs to further validate real world performance. Taking electrical performance into account we determine that infinite-symmetry 2D Fibonacci patterning far outperforms lower symmetry 12 fold and triangular arrangement. We believe that this is the first in depth investigation into 2D Fibonacci patterning in silicon solar cells.

Improving the efficiency of crystalline silicon solar cell through regulating their temperature using thin films of polyvinyl alcohol

Rising temperatures significantly affect the PV module, decreasing its voltage and lowering output power. Furthermore, temperature rises have been linked to several PV module failures or degradation modes. The purpose of this study analyzes polyvinyl alcohol PVA on crystalline silicon solar cells as a thermal insulation thin film. PVA thin films were prepared by dip-coating technique with a thickness of 1.15μm. The films exhibit suitable solar cell temperature controlling though it's an effect on masking the ultraviolet wavelength. The maximum temperature variation on the coating solar cell's surface was 4.5 °C as a comparison to a bare solar cell with irradiate exposure time 1800sec, and maximum efficiency obtained 18.99% in which Voc = 0.566 v and Isc = 330.2 mA when compared with bare solar cell 15.07% with benefit efficiency +3.92%. The concentrations of the polyvinyl alcohol influences on thin films and their effect on solar cell parameters are discussed.