Properties Of Solar Cells Research Articles

Deterioration of silver alloy electrode caused by photocatalytic reaction for crystalline silicon solar cells

In recent years, some minor elements are added into silver paste in order to improve the Ag/Si contact properties for crystalline silicon solar cells. Nevertheless, along with the addition of minor elements, the early discoloration of silver electrode appears on solar cells. In this work, the deteriorated silver alloy electrode on crystalline silicon solar cells was analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results prove that there exists a small amount of bismuth sulfide on the surface of the deteriorated electrode compared with normal electrode. An important finding is that the photocatalytic reaction of bismuth sulfide can accelerate the early discoloration of the silver alloy electrode. Then, the effect of silver alloy electrode deterioration on the peel force of ribbon for solar cells was investigated. The results indicate that the peel strength between ribbons and solar cells is decreased sharply due to the poor solderability of the deteriorated electrode. Additionally, it is found that the deteriorated silver alloy electrode can be recovered at 450 °C annealing for 60 s in a sintering furnace. After recovery experiments, the average peel force of ribbons attached to recovered busbars is up to 85% of normal busbars. The peel force of ribbon is significantly improved. The results obtained in this paper indicate that more attention should be given to the negative effect of minor elements on the electrode, when minor elements are added into silver paste to improve its performance.

Designing of phenothiazine-based hole-transport materials with excellent photovoltaic properties for high-efficiency perovskite solar cells (PSCs)

In this study, a series of highly efficient organic hole-transporting materials (HTMs) were designed using Schiff base chemistry by modifying a phenothiazine-based core with triphenylamine through end-capped acceptor engineering via thiophene linkers. The designed HTMs (AZO1-AZO5) exhibited superior planarity and greater attractive forces, making them ideal for accelerated hole mobility. They also showed deeper HOMO energy levels (−5.41 eV to −5.28 eV) and smaller energy band gaps (2.22 eV to 2.72 eV), which improved charge transport behavior, open-circuit current, fill factor, and power conversion efficiency of perovskite solar cells (PSCs). The dipole moments and solvation energies of the HTMs revealed their high solubility, making them suitable for the fabrication of multilayered films. The designed HTMs showed tremendous enhancements in power conversion efficiency (26.19 % to 28.76 %) and open-circuit voltage (1.43 V to 1.56 V), with higher absorption wavelength than the reference molecule (14.43 %). Overall, the Schiff base chemistry-driven design of thiophene-bridged end-capped acceptor HTMs is highly effective in enhancing the optical and electronic properties of perovskite solar cells.

Electrical properties for cold sprayed Nano copper oxide thin films

Abstract This work is a Copper oxide (CuO) thin films were effectively produced using cold spray technique. The process take place in an inert gas (helium) without using catalyst. Nano CuO was deposited on a glass slide, using helium as carrier gas heated to 100, 200, 300, and 400 °C, respectively on heated glass substrates at 300°C. The effect of structural and electrical properties was examined at each temperature for each film. AFM images show that the CuO thin film have different diameters ranging from 80 to 600 nm, and low surface roughness about 20.9 nm. The measured value of copper oxide resistivity was found to be decrease very much with the increasing temperature. All the result showed that copper oxide is suitable material for photovoltaic applications. This research is part of a larger work for the solar cells industry. Therefore, the aim of this research is to study the electrical properties of solar cells in the primary stages of manufacturing from available materials at low costs.

Mpact of laser surface modification on polycrystalline silicon photovoltaic cell by means of CO2 laser

In this research, we investigate the effect of laser texturing on the photo-electrical properties of the polycrystalline silicon solar cell. Laser surface texturing technique was used to achieve the texturing results, which based on the interaction between pulsed CO2 laser (10.6μm) and polycrystalline silicon used for solar cells. Four of photovoltaic solar cells have been textured in two dimensions in different ranges (1 cm x 1cm and 2 cm x 2 cm) with different line spacing. Solar cells with laser-modified surface were characterized by SEM as well as photo-electrically before and after texturing process. The obtained results showed that laser surface texturing with small grooves spacing, results in increasing of the melted silicon surface area which enhance the silicon electrical properties. Furthermore, it increases the optical path length inside the solar cell which enhances light trapping.

Effect of surface termination on electronic and optical properties of lead-free tin-based eco-friendly perovskite solar cell: a first principal study.

The lead (Pb)-based halide perovskites have been reported to be promising materials for photovoltaic applications; however, the presence of toxic lead in them concerns the environmental and health issues. In this work, we have, therefore, studied the lead-free and non-toxic tin-based halide perovskite, CsSnI3, which is an eco-friendly material with high power conversion efficiency, thus, being a potential candidate for photovoltaic applications. We have investigated the influence of CsI and SnI2-terminated (001) surfaces on structural, electronic and optical properties of lead-free tin-based halide perovskite CsSnI3 from the first principal calculations, based on density functional theory (DFT). The calculations of electronic and optical parameters are performed under the parameterisation of PBE_Sol for exchange-correlation functions conjugated with modified- Beche-Johnshon (mBJ) exchange potential. The optimised lattice constant, the energy band structure and the density of states (DOS) have been calculated for the bulk and different terminated surface structures. The optical properties of CsSnI3 are computed in terms of the real and imaginary part of absorption coefficient, dielectric function, refractive index, conductivity, reflectivity, extinction coefficient and electron energy loss. The photovoltaic characteristics for the CsI-termination are found to be better than the bulk and SnI2-terminated surfaces. This study reveals that optical and electronic properties can be tuned by selecting proper surface termination in halide perovskite CsSnI3. The CsSnI3 surfaces exhibit semiconductor behaviour with a direct energy band gap and a high value of absorption power in the ultraviolet and visible region, rendering these inorganic halide perovskite materials important for the eco-friendly and efficient optoelectronic devices.

Ionic liquids tailoring crystal orientation and electronic properties for stable perovskite solar cells

The crystallization behavior of perovskite films has a profound influence on the resulting defect densities, charge carrier dynamics and photovoltaic performance. Herein, we introduce ionic liquids into the perovskite component to tailor the crystal growth of perovskite films from a disordered to a preferential corner-up orientation and accordingly increase the charge carrier mobility to accelerate electron transport and extraction. Using time-resolved measurements, we probe the charge carrier generation, transport and recombination behavior in these films and related devices. We find the ionic liquid-containing samples exhibit lower defects, faster charge carrier transport and suppressed non-radiative recombination, contributing to higher efficiency and fill factor. Via operando grazing-incidence small- and wide-angle X-ray scattering measurements, we observe a light-induced lattice compression and grain fragmentation in the control devices, whereas the ionic liquid-containing devices exhibit a slight light-induced crystal reconstitution and stronger tolerance against illumination. Under ambient conditions, the non-encapsulated device with the pyrrolidinium-based ionic compound (Pyr14BF4) maintains 97% of its initial efficiency after 4368 h.

Implications of Electron Transport Layer and Back Metal Contact Variations in Tin–Lead Perovskite Solar Cells Assessed by Spectroscopic Ellipsometry and External Quantum Efficiency

The structural and optical properties of hybrid organic-inorganic metal halide perovskite solar cells are measured by spectroscopic ellipsometry to reveal an optically distinct interfacial layer among the back contact metal, charge transport, and absorber layers. Understanding how this interfacial layer impacts performance is essential for developing higher performing solar cells. This interfacial layer is modeled by Bruggeman effective medium approximations (EMAs) to contain perovskite, C60, BCP, and metal. External quantum efficiency (EQE) simulations that consider scattering, electronic losses, and the formation of nonparallel interfaces are created with input derived from ellipsometry structural-optical models and compared with experimental EQE to estimate optical losses. This nonplanar interface causes optical losses in short circuit current density (JSC) of up to 1.2 mA cm-2. A study of glass/C60/SnO2/Ag or Cu and glass/C60/BCP/Ag film stacks shows that C60 and BCP mix, but replacing BCP with SnO2 can prevent mixing between the ETLs to prevent contact between C60 and back contact metal and enable the formation of a planar interface between ETLs and back contact metals.

Poly(3-dodecylthiophene)-grafted multi-walled carbon nanotubes: an additive for improving charge transport properties of triple cation perovskite solar cells

Poly(3-dodecylthiophene)-grafted multi-walled carbon nanotubes: an additive for improving charge transport properties of triple cation perovskite solar cells

All-Tunicate Cellulose Film with Good Light Management Properties for High-Efficiency Organic Solar Cells.

Tunicate nanocellulose with its unique properties, such as excellent mechanical strength, high crystallinity, and good biodegradability, has potential to be used for the preparation of light management film with tunable transmittance and haze. Herein, we prepared a whole tunicate cellulose film with tunable haze levels, by mixing tunicate microfibrillated cellulose (MFC) and tunicate cellulose nanofibrils (CNF). Then, the obtained whole tunicate cellulose film with updated light management was used to modify the organic solar cell (OSC) substrate, aiming to improve the light utilization efficiency of OSC. Results showed that the dosage of MFC based on the weight of CNF was an important factor to adjust the haze and light transmittance of the prepared cellulose film. When the dosage of MFC was 3 wt.%, the haze of the obtained film increased 74.2% compared to the pure CNF film (39.2%). Moreover, the optimized tunicate cellulose film exhibited excellent mechanical properties (e.g., tensile strength of 168 MPa, toughness of 5.7 MJ/m3) and high thermal stability, which will be beneficial to the workability and durability of OSC. More interestingly, we applied the obtained whole tunicate cellulose film with a high haze (68.3%) and high light transmittance (85.0%) as an additional layer to be adhered to the glass substrate of OSC, and a notable improvement (6.5%) of the power conversion efficiency was achieved. With the use of biodegradable tunicate cellulose, this work provides a simple strategy to enhance light management of the transparent substrate of OSC for improving power conversion efficiency.

Unveiling the dimensional effects of SnO2 quantum dots and nanoparticles on the interfacial properties of perovskite solar cells

SnO2 is the most efficient and widely used electron conductor for perovskite solar cells (PSCs) due to its superior conductivity and high stability, however, the effect of SnO2's dimensions and sizes on the interfacial properties and device stability has often been ignored. Here, we investigate the relationship between device performance and electron conductors, including SnO2 quantum dots (SnO2 QD) and SnO2 nanoparticles (SnO2 NC). In contrast to SnO2 NC, SnO2 QD yields larger perovskite grains and high film uniformity, resulting in remarkable device efficiency and stability. Nonetheless, the device containing SnO2 QD exhibits a significant current-voltage hysteresis. By incorporating SnO2 QD and SnO2 NC to construct a bilayer structure, the hysteresis response and efficiencies of the devices have been drastically altered. PSCs based on SnO2 QDs exhibit a significant capacitive response at low frequencies and an exponential increase in capacitance at lower voltages, indicating significant charge accumulation at the interfaces. After being passivated with SnO2 NC in a bilayer structure, the wide depletion region at the high built-in potential provides a greater driving force for charge transfer, resulting in a significant reduction of hysteresis and an efficiency increase to >21%. This research provides insights into the significance of structural effects on electron conductors and will aid in enhancing the device performance of PSCs.

Identifying the relationships between subsurface absorber defects and the characteristics of kesterite solar cells

AbstractUnderstanding the defect characteristics that occur near the space‐charge regions (SCRs) of kesterite (CZTSSe) solar cells is important because the recombination loss at the CZTSSe/CdS interface is considered the main cause of their low efficiency. CZTSSe surfaces with different elemental compositions were formed without polishing (C00) and with polishing for 20 s (C20) and 60 s (C60). For C60, a specific region near the SCR was excessively Cu‐rich and Zn‐poor compared to C00 and C20. Various charged defects formed where the elemental variation was large. As the main deep acceptor defect energy level (Ea2) near the SCR increased, the efficiency, open‐circuit voltage deficit, and current density degraded, and this phenomenon was especially rapid for large Ea2 values. As the Ea2 near the SCR became deep, the carrier diffusion length decreased more for the CZTSSe solar cells with a low carrier mobility than for the CuInGaSe2 (CIGSe) solar cells. The large amplitude of the electrostatic potential fluctuation in the CZTSSe solar cells induced a high carrier recombination and a short carrier lifetime. Consequently, the properties of the CZTSSe solar cells were more strongly degraded by defects with deep energy levels near the SCR than those of the CIGSe solar cells.

Critical Role of Non-Halogenated Solvent Additives in Eco-Friendly and Efficient All-Polymer Solar Cells.

Organic solar cells (OSCs) demonstrating high power conversion efficiencies have been mostly fabricated using halogenated solvents, which are highly toxic and harmful to humans and the environment. Recently, non-halogenated solvents have emerged as a potential alternative. However, there has been limited success in attaining an optimal morphology when non-halogenated solvents (typically o-xylene (XY)) were used. To address this issue, we studied the dependence of the photovoltaic properties of all-polymer solar cells (APSCs) on various high-boiling-point non-halogenated additives. We synthesized PTB7-Th and PNDI2HD-T polymers that are soluble in XY and fabricated PTB7-Th:PNDI2HD-T-based APSCs using XY with five additives: 1,2,4-trimethylbenzene (TMB), indane (IN), tetralin (TN), diphenyl ether (DPE), and dibenzyl ether (DBE). The photovoltaic performance was determined in the following order: XY + IN < XY + TMB < XY + DBE ≤ XY only < XY + DPE < XY + TN. Interestingly, all APSCs processed with an XY solvent system had better photovoltaic properties than APSCs processed with chloroform solution containing 1,8-diiodooctane (CF + DIO). The key reasons for these differences were unraveled using transient photovoltage and two-dimensional grazing incidence X-ray diffraction experiments. The charge lifetimes of APSCs based on XY + TN and XY + DPE were the longest, and their long lifetime was strongly associated with the polymer blend film morphology; the polymer domain sizes were in the nanoscale range, and the blend film surfaces were smoother, as the PTB7-Th polymer domains assumed an untangled, evenly distributed, and internetworked morphology. Our results demonstrate that the use of an additive with an optimal boiling point facilitates the development of polymer blends with a favorable morphology and can contribute to the widespread use of eco-friendly APSCs.

Advanced carrier lifetime analysis method of silicon solar cells for industrial applications

Over the last few years, the silicon photovoltaic industry has been searching for efficient technologies to reduce the cost of cost/Wpeak by improving their conversion efficiency. However, with the silicon solar cell efficiency approaching the theoretical limit, it has become important to increase the efficiency distribution of cells by managing the loss factors existing in the production process. Although some companies are managing the efficiency distribution through in-line analysis equipment, a preventive action for reducing process defects has not yet been accomplished. To prevent process defects in advance, big data management is required to correlate the process conditions and solar cell parameters. Hence, an analysis method that can simply evaluate the detailed properties of completed solar cells is a key technique in future PV industries. In this paper, we introduce an advanced injection-dependent carrier lifetime analysis logic that can subdivide detailed recombination factors by fitting the carrier lifetime graph obtained through Suns-Voc measurement with a theoretical graph. The industrial applicability of this analysis method was tested with 160 commercially manufactured solar cells, demonstrating the expected quantitative gains of low-efficiency solar cells. The results show that the proposed method helps in determining the process priority for improving the efficiency distribution and provides a research direction for increasing the absolute efficiency.

Elucidating the mixing effect of dual polymers via physical blending on its physicochemical, thermal and electrical properties for dye-sensitized solar cells

Blending two different polymers through a physical blending is a wise alternative to create a new polymer with desired properties showing a synergistic effect of the individual polymers. In this work, polyacrylonitrile (PAN) and poly (1-vinylpyrrolidone-co-vinyl acetate) P(VP-co-VAc) were blended in a fixed amount of binary organic solvent of ethylene carbonate and propylene carbonate. The weight ratios were varied to 30:70, 50:50 and 70:30 wt%, respectively. Polymer electrolytes in a gel and solid form are safer than liquid ones. Thus 50:50PP and 70:30PP samples were selected and incorporated with iodide/triiodide redox mediators such as sodium iodide salt, 1-methyl-3-propylimidazolium iodide (MPII) ionic liquid and iodine for dye-sensitized solar cells (DSSC) application. Polymer electrolytes containing 50 wt.% of both PAN and P(VP-co-VAc) with iodide/triiodide redox mediator (50:50PP-IL) has achieved maximum ionic conductivity, short-circuit (JSC) current and power conversion efficiency (PCE, η) of 6.10 ×10−3 S cm−1, 11.1 mA cm−1 and 5.35%, respectively.

Modeling and simulation of the influence of quantum dots density on solar cell properties

Modeling and simulation of the influence of quantum dots density on solar cell properties

Machine learning applications for photovoltaic system optimization in zero green energy buildings

In this paper, the energy supply of a zero-energy building with 220 square meters is considered using optimized nanocomposite solar panels with respect to maximum efficiency. An optimized hybrid machine learning method plays a key role in presenting solar panel modeling with over 0.99% accuracy. Predicting the properties of the nanomaterial solar cell in four different seasons is performed by efficient support vector machines (SVM), and k-nearest neighbors (KNN) machine learning algorithms. In addition, the KNN algorithm is optimized by the Particle Swarm Optimization (PSO) method to improve the capabilities of KNN and reveal the best performance criteria for the photovoltaic modeling characteristics. The parameters of the nanocomposite cells are optimized using the proposed novel Multidisciplinary Optimization Method (MDO) to increase the efficiency of the solar panel by up to 170%. Optimization of solar cell performance with nanocomposite material under energy consumption constraints is carried out to propose the best construction of cells with 3 layers. The presented approach as a solution and indicator for the next generation of commercial and residential buildings can increase the potential values of solar cells to at least 70%.

Synergistic influence of plasmonic Ag nanoparticles/La0.6Sr0.4CoO3/TiO2 heterostructured photoanodes boosted solar energy harvesting by dye-sensitized photovoltaics

Several hybrid composite photoanodes composed of easily synthesizable and cost-effective La0.6Sr0.4CoO3 (LSCO) nanoparticles (obtained by the sol–gel method) combined with TiO2 nanoparticles were prepared and investigated for their light-harvesting properties in dye-sensitized solar cells (DSSCs). To develop these effective photoelectrode nanomaterials for DSSCs, the pure inorganic perovskite La0.6Sr0.4CoO3 (2, 4, 6 and 8 %) as well as plasmonic silver nanoparticles decorated La0.6Sr0.4CoO3 (6 % La0.6Sr0.4CoO3/x%Ag, x = 1, 2.5, 5, 7.5 and 10 %) nanomaterials were added into the TiO2 photoanodes. The XRD, FESEM, EDS, BET FT-IR, DRS, PL, and dye loading were used to study all nanostructured photoanodes' structural and morphological properties. Based on the photovoltaic tests, it was found that the DSSC fabricated with TiO2 + 6 % La0.6Sr0.4CoO3 achieved the most enhanced efficiency of 6.04 % among the TiO2 + La0.6Sr0.4CoO3 (2, 4, 6, and 8 %) containing devices. Furthermore, the power conversion efficiency (PCE) values were increased when Ag plasmonic nanoparticles were decorated on the La0.6Sr0.4CoO3 crystalline lattice. The greatest PCE = 7.34 % was attained for the optimized solar cell assembled by TiO2 + 6 % La0.6Sr0.4CoO3/7.5 %Ag photoanode which yielded ∼ 2.35 and 1.21 folds increase in PCE compared to the DSSCs containing pristine TiO2 nanoparticles and TiO2/6% La0.6Sr0.4CoO3 photoelectrodes, respectively. Based on the photoelectrochemical analysis, this structure exhibited the fastest electron transport rate, the most effective photo-induced charge separation, the greatest electron collection efficiency, the highest dye loading capacity, and the least photoluminescence intensity (charge recombination), which all contributed to increasing the DSSC device's efficiency.

Enhanced Photovoltaic Properties of Dye-Sensitized Solar Cells through Ammonium Hydroxide-Modified (Nitrogen-Doped) Titania Photoanodes

Doping is a unique strategy to modulate the optical and electronic properties of semiconducting materials. This study reports a facile approach to fabricate nitrogen-doped TiO2 (N-doped TiO2) photoanode for DSSC application. A solid-state reaction was employed to synthesize a series of N-doped TiO2 nanoparticles with different volumetric ratios of nitrogen dopant and the TiO2 host. The NH4OH as a nitrogen dopant was combined with P25-TiO2 via grinding followed by calcination at 500°C. The synthesized nanoparticles were extensively characterized by XRD, XPS, EDX, SEM, and TEM techniques. XRD results suggested that the incorporation of nitrogen had not altered the structure of the TiO2 lattice, and the presence of nitrogen was confirmed through the XPS and EDX spectroscopies. SEM and TEM images, obtained before and after N doping, showed that N-doped TiO2 nanoparticles with low amounts of NH4OH (10 and 20 μL) had retained their spherical shapes and sizes while use of higher amounts of the N dopant (30 and 40 μL) had led to agglomeration of nanoparticles. BET and BJH analyses revealed that the optimized N-doped TiO2 with 20 μL of NH4OH (20N-TiO2) possesses the highest average pore diameter of 15.99 nm. Furthermore, the UV-visible spectroscopic analysis confirmed a red shift in the optical absorption edge on N doping and the corresponding bandgap reduced from 3.15 to 2.94 eV with increase in the amount of NH4OH from 0 to 40 μL. Eventually, DSSCs were fabricated using the prepared pure TiO2 and N-doped TiO2 photoanodes, N719 dye,I−/I3−electrolyte, and Pt counter electrode, followed by investigating their performance under simulated irradiation with 100 mW/cm2 intensity with AM 1.5 filter. The photoanode doped with 20 μL of NH4OH (20N-TiO2) exhibited the highest power conversion efficiency (PCE) of about 6.16%, which was 20% higher than that of the control device, with improvedJSC. This enhancement inJSCcould be predominantly attributed to higher dye uptake along with marginal contribution by reduced rate of recombination. Among the reported studies on DSSCs with N-doped P25-TiO2 photoanodes, our method gives the best efficiencies for the DSSCs.

All-Vacuum-Deposited Bifacial Cu2ZnSnSe4 Photovoltaic Cells with Sputtered Cd-Free Buffer Layer

By depositing metal precursors on fluorine-doped tin oxide substrates using evaporation and postselenisation and modifying the number of stacked metallic precursor layers, this study systematically analysed the effect of cation changes on the absorber layer and the solar cell properties of Cu2ZnSnSe4 (CZTSe). Furthermore, in this study, an all-vacuum method was adopted to prepare a cadmium-free bifacial CZTSe solar cell and conducted damp heat tests on the device. The findings indicate that the increase in the number of stacked metallic precursor layers suppresses secondary phase generation, thereby enhancing the film performance and bifacial solar cell characteristics. The cadmium-free bifacial CZTSe solar cell prepared in this study exhibited the efficiency of 4.13% under bifacial incident light. Moreover, the degradation of the device was effectively mitigated in the damp heat tests compared with previously reported devices with metal substrates. These findings can provide new directions for research and lead to novel applications for CZTSe solar cells in the future.

Impact of concentration of DMF and H2O on photovoltaic properties of SnO2-based planar perovskite solar cells

SnO2-based planar perovskite solar cells were prepared via the sol-gel method and DMF was used to coordinate with SnCl4 which ensures to form a stable Sn-sol. A certain amount of H2O was added to induce SnCl4 to convert to SnO2 and reduce the remaining of OH− and Cl− on the surface of SnO2 film. Compared with the PCE of pristine SnO2-based cells (17.14%), the W-SnO2-based cell in revers scan under simulated AM1.5G illumination increases to 19.07%. The open-circuit voltage of the W-SnO2-based cells increases to 1128 mV, compared with that of the pristine SnO2-based cell (1090 mV). The unencapsulated cells maintain 90% of initial efficiency after stored in Ar glovebox for 30 days.