Maximum Solar Cell Efficiency Research Articles

Modeling the Output Performance of Al0.3Ga0.7As/InP/Ge Triple-Junction Solar Cells for a Venus Orbiter Space Station

The performance of Al0.3Ga0.7As/InP/Ge triple-junction solar cells (TJSC) at the geosynchronous orbit of Venus had been simulated in this paper by assuming that the solar cells were put on a hypothetical Venus orbiter space station. The incoming solar radiation on TJSC was calculated by a blackbody radiation formula, while PC1D program simulated the electrical output performance. The results show that the incoming solar intensity at the geosynchronous orbit of Venus is 3000 W/m2, while the maximum solar cell efficiency achieved is 38.94%. Considering a similar area of the solar panel as the International Space Station (about 2500 m2), the amount of electricity produced by Venus orbiter space station at the geosynchronous orbit of Venus is 2.92 MW, which is plenty of energy to power the space station for long-term exploration and intensive research on Venus.

Theoretical and experimental study on the uniformity of reflective high concentration photovoltaic system with light funnel

Abstract The efficiency of GaAs solar cell was significantly reduced resulting from non-uniformity of energy flux-density on receiver surface, and damage of solar cells was made by “hot spots”. In this paper, a light funnel is added between the concentrator and the receiver to improve the uniformity of energy flux-density on receiver surface, which is designed according to the ray tracing method. The simulation result shows that the uniformity of the energy flux-density on the receiver surface is 92.26%, which agrees with the experimental result (94.64%). According to the maximum output efficiency of GaAs solar cell, the layout range of the cell is determined. The simulation results shown that the cell is arranged in the radius of 58 mm, which is similar to the experimental value (60 mm), and the effective area rate of the photoelectric conversion is 69.4%. At normal operation temperature (20 °C), the photoelectric conversion efficiency is 29.64%, and the total efficiency is about 83%.

Reassessment of intrinsic lifetime limit in n-type crystalline silicon and implication on maximum solar cell efficiency

Unusually high carrier lifetimes are measured by photoconductance decay on n-type Czochralski-grown silicon wafers of different doping concentrations, passivated using plasma-assisted atomic-layer-deposited aluminum oxide (Al2O3) on both wafer surfaces. The measured effective lifetimes significantly exceed the intrinsic lifetime limit previously reported in the literature. Several prerequisites have to be fulfilled to allow the measurement of such high lifetimes on Al2O3-passivated n-type silicon wafers: (i) large-area wafers are required to minimize the impact of edge recombination via the Al2O3-charge-induced inversion layer, (ii) an exceptionally homogeneous Al2O3 surface passivation is required, and (iii) very thick silicon wafers are needed. Based on our lifetime measurements on n-type silicon wafers of different doping concentrations, we introduce a new parameterization of the intrinsic lifetime for n-type crystalline silicon. This new parameterization has implications concerning the maximum reachable efficiency of n-type silicon solar cells, which is larger than assumed before.

Thickness optimization of CdS/ZnO hybrid buffer layer in CZTSe thin film solar cells using SCAPS simulation program

In CZTSe thin film solar cell, CZTSe/CdS as absorber/buffer layer has been used and ZnO is used as a window layer. CdS as buffer layer have high efficiency but it is toxic due to cadmium. So to reduce the cadmium usage, a hybrid buffer layer of ZnO/CdS is proposed and the numerical study has been performed using SCAPS-1D simulator. The thickness of ZnO/CdS buffer layer has been optimized at ZnO-15 nm/CdS-65 nm, for maximum solar cell efficiency. The solar cell with hybrid buffer layer of ZnO/CdS exhibits more efficiency compared to the solar cell using only CdS or only ZnO as buffer layers. The solar cell efficiency variation with temperature has been studied for CdS, ZnO and CdS/ZnO buffer layer and observed that the variations are almost same for all the three layers.

Planar structured perovskite solar cells by hybrid physical chemical vapor deposition with optimized perovskite film thickness

The thickness of perovskite absorber layer is a critical parameter to determine a planar structured perovskite solar cell’s performance. By modifying the spin coating speed and PbI2/N,N-dimethylformamide (DMF) solution concentration, the thickness of perovskite absorber layer was optimized to obtain high-performance solar cells. Using a PbI2/DMF solution of 1.3 mol/L, maximum power conversion efficiency (PCE) of a perovskite solar cell is 15.5% with a perovskite film of 413 nm at 5000 rpm, and PCE of 14.3% was also obtained for a solar cell with a perovskite film of 182 nm thick. It is derived that higher concentration of PbI2/DMF will result in better perovskite solar cells. Additionally, these perovskite solar cells are highly uniform. In 14 sets of solar cells, standard deviations of 11 sets of solar cells were less than 0.50% and the smallest standard deviation was 0.25%, which demonstrates the reliability and effectiveness of hybrid physical chemical vapor deposition (HPCVD) method.

Analysis of The Impact of Environmental Factors on Efficiency of Different Types of Solar Cells

Solar energy is pollution free and is abundantly available. Solar energy utilizes sunlight to give heat, light,electricity, etc. for domestic and industrial uses. With the alarming reduction of major energy resources such as coal, petroleum and gas, combined with the environmental deprivation caused by the process of harnessing these energy sources, it has become a necessity to capitalize renewable energy resources that would power the future energy needs adequately without degrading the environment through greenhouse gas release. Commercially available solar cells have efficiencies in the range 10-20%. Although recent breakthrough in the technology of solar cells shows significant improvement but the fact that the maximum solar cell efficiency still falls in the less than 20% range shows there is huge room for improvement. Mathematical models of the three types of solar cells (Monocrystalline, Polycrystalline and Thin film) were simulated using MATLAB. The values of irradiance and Temperature were varied and the effect of these in the efficiency of the solar cell was seen. Then an accumulative effect was seen which shows the effect of wind on the efficiency of solar cell. The data of different cities of Balochistan was also simulated and the results were seen. It was seen in this research that the temperature and irradiance affect the efficiency of the solar cell a lot and that the thin film solar cell is the most temperature tolerant solar cell.

Analysis of The Impact of Environmental Factors on Efficiency of Different Types of Solar Cells

Solar energy is pollution free and is abundantly available. Solar energy utilizes sunlight to give heat, light,electricity, etc. for domestic and industrial uses. With the alarming reduction of major energy resources such as coal, petroleum and gas, combined with the environmental deprivation caused by the process of harnessing these energy sources, it has become a necessity to capitalize renewable energy resources that would power the future energy needs adequately without degrading the environment through greenhouse gas release. Commercially available solar cells have efficiencies in the range 10-20%. Although recent breakthrough in the technology of solar cells shows significant improvement but the fact that the maximum solar cell efficiency still falls in the less than 20% range shows there is huge room for improvement. Mathematical models of the three types of solar cells (Monocrystalline, Polycrystalline and Thin film) were simulated using MATLAB. The values of irradiance and Temperature were varied and the effect of these in the efficiency of the solar cell was seen. Then an accumulative effect was seen which shows the effect of wind on the efficiency of solar cell. The data of different cities of Balochistan was also simulated and the results were seen. It was seen in this research that the temperature and irradiance affect the efficiency of the solar cell a lot and that the thin film solar cell is the most temperature tolerant solar cell.

Photovoltaic performance and impedance spectroscopy of ZnS-Cu-Go nanocomposites

In this work, novel, non-toxic and cost effective ZnS-Cu-GO nanocomposite is synthesized via wet chemical route to study its photovoltaic properties. Three samples including ZnS,ZnS-Cu and ZnS-Cu-GO were prepared and deposited as sensitizers on ZnO coated FTO substrates to assemble PV devices.The samples were characterized using UV–Vis NIR spectroscopy, Atomic force microscopy (AFM).Electrochemical impedance spectroscopy (EIS) and AM 1.5 Sun Simulator. It was observed that ZnS-Cu-GO exhibitedsuperiorchargetransport, remarkably high open circuit voltage(0.8V) and Fill factor (0.806).The current density significantly enhanced and maximum solar cell efficiency was observed for ZnS-Cu-GO based PV device. A pronounced red shift of 360nm in the absorption spectra was observed in the ZnS-Cu-GO due to fine dispersion of GO sheets.The AFM analysis showed that incorporation of GO and Cu maximized grain density and trench like grain boundaries in ZnS-Cu-GO which facilitated charge transport mechanism.A detailed electrochemical impedance study to probe charge dynamics in the prepared PV devices is presented herein.

Fabrication, characterization and comparison of DSSC using anatase TiO2 synthesized by various methods

In this study, anatase TiO2 nanoparticles were synthesized by three techniques, namely, sol–gel, acid-base co-catalyst and room temperature colloidal methods. The synthesized materials were characterized by X-ray diffraction, scanning electron microscopy, pore diameter, pore volume and surface area. The dye-sensitized solar cells were fabricated using the synthesized materials and characterized for incident photon to current conversion efficiency, photocurrent density to photo voltage measurement and electrochemical impedance analysis. Among the studied materials, TiO2 synthesized by sol–gel method displayed highest photon to current conversion of 76.8% and a maximum solar cell efficiency of 7.85% with Jsc of 14.75mA/cm2, Voc of 0.76V and FF of 0.7. This is the first study to report a high power conversion efficiency of DSSC using a sol–gel synthesized titania and its comparison with other two synthesized materials. The high power conversion efficiency of the solar cell using TiO2 synthesized by sol–gel method is attributed to its characteristic properties such high surface area, larger pore diameter and larger pore volume and highest dye loading capacity.

Efficiency of Solar Cells Employing Natural Dyes with Plasmonic Nano Particle Based Photo Anode

Cheap and efficient dye sensitized solar cells (DSSCs) can be prepared using natural dyes responding in visible region of solar spectrum. Localized surface Plasmon resonance (LSPR) plays a very important role for the improvement in the efficiency of DSSCs by using Plasmonic nanoparticles (PNPs) for exploiting the visible portion of the solar radiation by transferring the energy from dye to PNP. This energy transfer from dye to low cost semiconductor TiO2 through PNP increases the overall photo catalytic activity. In the present study, natural and synthetic dyes are prepared and the optical transmittance and absorbance of the dyes are measured in the wavelength range of 250nm to 850nm using UV-Vis spectroscopy and they are used in DSSC. Natural dyes extracted from fruits and synthetic dye based on Ru metal complex is used as sensitizers. Photo Conversion Efficiency (PCE) of the solar cells utilizing different dyes are compared. Out of the various natural dyes, beetroot and strawberry extracts based dyes show good absorbance in the visible range of electromagnetic spectrum. On the other hand synthetic dye based on Ru complex shows strong absorbance over a wide range of visible spectrum. The absorbance increases with increase in concentration of Ru in ethanol. The extracts of beetroot, strawberry and mixed fruits show a peak in absorbance spectra at 501nm, 416nm and 332nm respectively, indicating the absorption over wide range of visible spectrum. Maximum efficiency of solar cell obtained with synthetic and natural dyes are 5% and 1.5% respectively.

Hydrothermal growth of highly monodispersed TiO2 nanoparticles: Functional properties and dye-sensitized solar cell performance

Monodispersed anatase TiO2 nanoparticles were synthesized by hydrothermal method using citric acid as a capping agent. The effect of citric acid and the growth time on the formation of TiO2, functional properties and dye-sensitized solar cell performances were investigated. X-ray diffraction pattern (XRD) and Raman spectroscopy results revealed that the TiO2 nanoparticles possess the anatase phase. Transmission electron microscopy (TEM) measurement revealed the formation of spherical nanoparticles with monodispersity in size and morphology. An average size of 14nm was obtained for the growth period of 15h. The maximum efficiency (η) of dye-sensitized solar cell was achieved for TiO2 nanoparticles grown for 15h as 7.66% which was higher than that of commercial P25 TiO2 (5.23%) and uncapped nanoparticles (3.68%).

Realizing a facile and environmental-friendly fabrication of high-performance multi-crystalline silicon solar cells by employing ZnO nanostructures and an Al2O3 passivation layer

Nowadays, the multi-crystalline silicon (mc-Si) solar cells dominate the photovoltaic industry. However, the current acid etching method on mc-Si surface used by firms can hardly suppress the average reflectance value below 25% in the visible light spectrum. Meanwhile, the nitric acid and the hydrofluoric contained in the etching solution is both environmental unfriendly and highly toxic to human. Here, a mc-Si solar cell based on ZnO nanostructures and an Al2O3 spacer layer is demonstrated. The eco-friendly fabrication is realized by low temperature atomic layer deposition of Al2O3 layer as well as ZnO seed layer. Moreover, the ZnO nanostructures are prepared by nontoxic and low cost hydro-thermal growth process. Results show that the best passivation quality of the n+ -type mc-Si surface can be achieved by balancing the Si dangling bond saturation level and the negative charge concentration in the Al2O3 film. Moreover, the average reflectance on cell surface can be suppressed to 8.2% in 400–900 nm range by controlling the thickness of ZnO seed layer. With these two combined refinements, a maximum solar cell efficiency of 15.8% is obtained eventually. This work offer a facile way to realize the environmental friendly fabrication of high performance mc-Si solar cells.

Simulation-based Efficiency Gain Analysis of 21.2%-efficient Screen-printed PERC Solar Cells

Passivated Emitter and Rear Cells (PERC) with efficiencies well above 20% are likely to become the next mass production technology. A quantification of all power loss mechanisms of such industrial PERC cells is helpful in prioritizing future efficiency improvement measures. We report on a numerical simulation of the power losses of a 21.2%-efficient industrial PERC cell using extensive experimental input data. Our synergetic efficiency gain analysis relies on deactivating single power loss mechanisms in the simulation at a time to access the full potential power gain related to that mechanism. The complete analysis therefore explains the efficiency gap between the industrial PERC solar cell and the theoretical maximum efficiency of a crystalline Si solar cell. Based on the simulations, the largest single loss mechanism is front grid shadowing followed by recombination in the emitter and its surface. All individual resistive losses, all individual optical losses and all (avoidable) individual recombination losses sum up to efficiency gains of 0.8%, 1.6%, and 1.3%, respectively, which is 3.7% in total. The efficiency gap between real and ideal solar cell is, however, much larger with 7.3%. The discrepancy is mainly due to the non-linear behaviour of recombination-based power losses which adds synergetic efficiency enhancements.

A comprehensive theoretical study of halide perovskites ABX3

Solar cells based on halide perovskites have recently been attractive due to their excellent power conversion efficiency (PCE), lower cost and simple manufacture. Here, a series of halide perovskites (ABX3: A = CH3NH3, CH(NH2)2, Cs, Rb; B=Pb, Sn, Ge; X = I, Br, Cl, F) were investigated by Density Functional Theory (DFT) calculations, together with Shockley-Queisser Maximum Solar Cell Efficiency (S-Q) and Spectroscopic Limited Maximum Efficiency (SLME) mathematical models. The results indicate that: the electronic structure of germanium perovskites bears a close similarity to that of lead perovskites with a small energy difference between the nonbonding orbital and antibonding orbitals, but with a large energy difference comparing with that of tin perovskites (0.6–1.7 eV for CsGeI3 at Z point of the Brillouin zone, 0.7–1.4 eV for CH3NH3PbI3 and 1.4–2.2 eV for CH3NH3SnI3 at R point of the Brillouin zone), which is attributable to the atomic level, where the 4s orbital energy of Ge (−11.5 eV) is close to the 6s orbital energy of Pb (−11.6 eV), but the 5s orbital energy of Sn (−10.1 eV) is significantly high. Therefore, germanium perovskites possess as high absorption coefficient around solar spectrum as lead perovskites, while tin perovskites only have low absorption coefficient, which makes the short-circuit current of CsGeI3 and CH3NH3PbI3 (0.017 Acm−2 and 0.016 Acm−2, simulated by SLME with a 200 nm absorber under AM1.5G) are higher than that of CH3NH3SnI3 (0.015 Acm−2) even if the bandgap of CsGeI3 and CH3NH3PbI3 (1.51 eV and 1.55 eV) are larger than that of CH3NH3SnI3 (1.21 eV). Meanwhile, the effective mass of electrons and holes are approximate for germanium perovskites and lead perovskites (0.14:0.19 for CsGeI3 and 0.12:0.12 for CH3NH3PbI3), indicating a balanced electrons and holes transport, whereas the electrons transport is much slower than the holes transport for tin perovskites due to the effective mass of electron is much larger than that of hole (0.17:0.04 for CH3NH3SnI3). As a result, the PCE of CsGeI3 (27.9%) and CH3NH3PbI3 (26.7%) is higher than that of CH3NH3SnI3 (19.9%).

Impact of Laser-Induced Oxidation on Silicon Wafer Solar Cells’ Performance

Lasers are frequently used to locally open dielectric layers for contacting the front or rear side of advanced silicon wafer solar cell architectures. For reasons of cost, laser processes are usually carried out in ambient environment, which inevitably leads to the oxidation of silicon. In order to achieve maximum solar cell efficiency, the laser processing has to be optimized thoroughly. The current research only focuses on minimizing laser-induced defects in silicon. However, our investigation shows another side effect of laser ablation, i.e., laser-induced oxidation, which is often neglected and undesirable for the subsequent metallization process. In this paper, we investigated the impact of laser-induced oxidation, which is caused by laser ablation in air, on the performance of silicon wafer solar cells. We show that by applying a postlaser etching step, laser-induced defects and oxide film can be removed effectively, providing improved conditions for the subsequent metallization process.

Effect of photoanode surface coverage by a sensitizer on the photovoltaic performance of titania based CdS quantum dot sensitized solar cells

In spite of the promising design and architecture, quantum dot sensitized solar cells (QDSSCs) have a long way to go before they attain the actual projected photoconversion efficiencies. Such an inferior performance displayed by QDSSCs is primarily because of many unwanted recombination losses of charge carriers at various interfaces of the cell. Electron recombination due to back electron transfer at the photoanode/electrolyte interface is an important one that needs to be addressed, to improve the efficiency of these third generation nanostructured solar cells. The present work highlights the importance of conformal coverage of CdS quantum dots (QDs) on the surface of the nanocrystalline titania photoanode in arresting such recombinations, leading to improvement in the performance of the cells. Using the successive ionic layer adsorption and reaction (SILAR) process, photoanodes are subjected to different amounts of CdS QD sensitization by varying the number of cycles of deposition. The sensitized electrodes are characterized using UV–visible spectroscopy, cyclic voltammetry and transmission electron microscopy to evaluate the extent of surface coverage of titania electrodes by QDs. Sandwich solar cells are then fabricated using these electrodes and characterized employing electrochemical impedance spectroscopy and J–V characteristics. It is observed that maximum solar cell efficiency is obtained for photoanodes with conformal coating of QDs and any further deposition of sensitizer leads to QD aggregation and so reduces the performance of the solar cells.

Clarification of the relation between the grain structure of industrial grown mc-Si and the area fraction of electrical active defects by means of statistical grain structure evaluation

This paper presents results of a statistical investigation of the grain size-, grain orientation- and grain boundary type distribution of six industrially grown conventional multicrystalline (mc-Si) silicon bricks and six high performance (hp) mc-Si bricks of different producers. It was found that hp mc-Si wafers have a more uniform initial grain size (coefficient of variation CV < 2.5) and grain orientation (CV < 1.5) distribution, with a smaller mean grain size (<4 mm2) and a much higher length fraction of random grain boundaries (>60%) in comparison to the conventional mc-Si wafers. Despite the totally different initial grain structures between the hp and conventional mc-Si bricks the grain structure of the top wafers is more or less comparable. It was concluded that the grain structure development of the hp mc-Si bricks is driven by an energy minimization due to the surface energy as well as the grain boundary energy. The grain structure investigations show clearly that especially the initial grain structure of the bricks significantly influences the area fraction of electrical active defects as well as the solar cell efficiency. The hp mc-Si bricks show the lowest area fraction of electrical active defects up to 4% and the highest solar cell efficiency of 18.8%, whereas the conventional mc-Si bricks have an area fraction of electrical active defects up to 14% and a maximum solar cell efficiency of about 18.4%.

One-Step Electrochemical Polymerization of Polyaniline Flexible Counter Electrode Doped by Graphene

To improve the photoelectric property of polyaniline (PANI) counter electrode using for flexible dye-sensitized solar cell (DSSC), graphene (GN) was doped in PANI films covered on flexible conducting substrate by one-step electrochemical method, and then GN/PANI composites are characterized by scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR), four probe instrument, and so on. The results show that PANI particles can be electrodeposited on the surface of GN sheets as the potential rising to 2.0 V. This formed unique PANI-GN-PANI lamellar structure owing to the strong interaction of conjugatedπelectron between GN and PANI results in the superior conductivity and catalytic performance of GN/PANI electrode. The maximum conversion efficiency of dye-sensitized solar cell with this counter electrode reaches 4.31%, which is much higher than that of GN-free PANI counter electrode.

One-step Electrodeposition of Metal Precursors from a Deep Eutectic Solvent for Cu(In,Ga)Se2 Thin Film Solar Cells

Electrodeposition and annealing (EDA) is a low-cost and promising growth route for Cu(In,Ga)Se2 (CIGSe). One of the main drawbacks of this method is the difficulty in controlling gallium deposition from aqueous electrolytes due to the interference of the hydrogen evolution reaction. Thus, to avoid this parasitic reaction and make the deposition more energy efficient we deposit from a deep eutectic solvent (DES). In this work we investigate the one step electrodeposition of copper, indium and gallium from the DES choline chloride:urea (ChCl:U – 1:2). The electrochemical behaviour of the ChCl:U-CuCl2-InCl3-GaCl3 system was studied by rotating disk electrode cyclic voltammetry. This analysis revealed several redox responses which related to the deposition and stripping of different Cux(In,Ga)y intermetallics. The morphology of the deposits depended primarily on the metal salt concentration in solution, since dendrites as well as compact layers were obtained. The metal precursor layers were successfully converted to CIGSe by selenisation, whilst avoiding Ga segregation. However, the maximum solar cell efficiency obtained was 2.7%. With this work we introduced a versatile one-step deposition method where the morphology of the precursor can be controlled by tuning solution composition and by introducing several potential steps during growth.

Controlled bandgap CuIn1 − xGax(S0.1Se0.9)2 (0.10 ≤ x ≤ 0.72) solar cells from electrodeposited precursors

Electrodeposition and post-annealing is a potentially low-cost industrial growth route for Cu(In,Ga)(S,Se)2 solar cells. Nevertheless, this process is limited by the difficulty to introduce gallium in the precursor and by the segregation of gallium during the annealing step. Previously, we countered the former problem by co-electrodepositing In and Ga from a Deep Eutectic Solvent, accurately controlling the Ga/(Ga+In) (referred to as Ga/III) ratio of the precursor. In order to avoid segregation we employed a three-step annealing procedure, introducing a limited quantity of sulphur on the surface of the absorber. In this work, absorbers and solar cells originating from electrodeposited precursors with 0.10≤Ga/III≤0.72 are characterised. X-ray diffraction results show that the Cu(In,Ga)Se2 112 peak shifts to higher angles with increasing Ga content, in agreement with the expected composition values. Additionally, these results show identical incorporation of sulphur in all samples. Photoluminescence, external quantum efficiency, and current–voltage measurements corroborate the X-ray diffraction results. Controlled incorporation of Ga, over a large Ga/III range, is achieved for electrodeposited and post-annealed Cu(In,Ga)(S,Se)2 absorbers. A maximum solar cell efficiency of 9.8% was obtained.