Efficiency Of Silicon Solar Cells Research Articles

CONSTRUCTIVE SOLUTION OF HIGHLY EFFECTIVE PHOTOENERGY MODULE: DEVELOPMENT AND EXPERIMENTAL TESTING

Based on experimental study and computer modeling of working temperature influence on the efficiency of Chinese production silicon solar cells identified temperature dependence of efficiency shows the feasibility of using Chinese production Si-SC in the construction of photovoltaic thermal system, which together with the heat pump is part of a combined system for hot water supply, heating and air conditioning. Based on a detailed analysis of the working temperature influence on the efficiency of photovoltaic processes that determine the solar cells work, it has been developed the optimal construction and technological solution of hybrid solar generated module, the main feature of which is the heat exchange block, designed to reduce the solar cells working temperature. The experimental testing of hybrid modules samples equipped with developed cooling system, high-voltage part of power take-off system demonstrates their reliability and high efficiency which allow to achieve the such module efficiency up to 18.5 %.

Effect of Temperature on Limit Photoconversion Efficiency in Silicon Solar Cells

The photoconversion efficiency and the temperature coefficient of an ideal silicon solar cell are investigated theoretically as a function of the base thickness. It is found that the efficiency depends nonmonotonically, whereas the temperature coefficient increases logarithmically with the thickness. Under the AM1.5 G illumination conditions at the temperature of 25 $^\circ$ C, the maximal efficiency value of 29.7% at the thickness 90 $\mu$ m is obtained. The temperature coefficient has the value of 0.234%/K at the optimal base thickness. Analogous calculations were also performed for nonideal solar cells, in which the extrinsic recombination mechanisms, doping, and parasitic series and shunt resistance play a role. It is shown that all of these factors, except for the shunt resistance, result in an increase of the temperature coefficient relative to its value obtained for an ideal solar cell. In other words, the thickness-dependent value obtained for an ideal solar cell is the theoretical lower limit of the efficiency temperature coefficient if the shunting effect is negligible. The shunting resistance, in contrast, results in a further reduction of the temperature coefficient relative to the value obtained for an ideal solar cell. The implications of these findings in the solar cell design are discussed.

Improving the efficiency of silicon solar cells using in situ fabricated perovskite quantum dots as luminescence downshifting materials

Abstract Luminescence downshifting (LDS) layer integration has been proven to be an efficient way to ameliorate the poor UV-blue spectral response and improve the power conversion efficiency (PCE) for solar cells (SCs). By employing an in situ fabricated CH3NH3PbBr3 (CH3NH3 = methylammonium, MAPbBr3) quantum dot/polyacrylonitrile (PAN) composite film as the LDS layer, we observed a clear enhancement in the external quantum efficiency (EQE) for silicon SCs, predominantly in the UV-blue region. With a theoretically calculated intrinsic LDS efficiency (η LDS) of up to 72%, silicon SCs with the LDS layer exhibited an absolute value of 1% for PCE improvement in comparison to those without the LDS layer. The combination of easy fabrication and low cost makes it a practical way to achieve photovoltaic enhancement of Si-based SCs.

CdSe/CdS core/shell in polyacrylamide polymer matrix for Quantumdots Luminescent solar concentrator

Luminescent solar concentrator (LSC) are used to enhance photoresponsivity of solar cell. The Quantumdots luminescent solar concentrator (QDLSC) consists of CdSe/CdS core/shell nanoparticles embedded in polyacrylamide polymer matrix positioned on the top surface of the silicon solar cell. This procedure improves the conversion efficiency of the bare silicon solar cell. The conversion efficiency of the solar cell has increased from 7.3% to 10.3%. this improvement is referred to the widening of the response spectral region window of the a- Si. Solar cell.

A downshifting Eu3+ doped glass embedded with concave pyramid microstructure to improve the efficiency of silicon solar cell

The average photoelectric conversion efficiency (PCE) of a bare mono crystalline silicon solar cell is 14.71% ± 0.03% under AM1.5. It decreases to 14.20% ± 0.005% when covering an un-doped flat glass on the solar cell, and it goes down to 14.10% ± 0.005% by using a 5 wt% Eu3+ doped glass. The absorptions of the Eu3+ doped CPM glass one-to-one match the excitation spectra at 362, 381, 393, 400, 413 and 464 nm, which are related to the transitions of 7F0→(5D4, 5G2, 5L6, 5D3), 7F1→5D3, and 7F0→5D2, respectively. In addition, a concave pyramid microstructure (CPM) is embedded in the glass surface to increase light transmittance. The average PCE increases to 14.61% ± 0.07% when a 5 wt% Eu3+ doped CPM glass covers on the silicon solar cell. Compared with the un-doped flat glass, a net increase of the PCE is 0.41%, where the 0.16% increment of PCE is from the lighting trapping of the CPM structure, and the downshifting of near ultraviolet (NUV) light by Eu3+ ion donates the other 0.25% increment. It confirms that the as-prepared Eu3+ doped CPM glass has a good downshifting and antireflection function.

21.3%-efficient n-type silicon solar cell with a full area rear TiOx/LiF/Al electron-selective contact

In this work, we investigate an efficient electron-selective passivating contact with TiOx/LiF/Al contact structure, which offers both low surface recombination and specific contact resistance. Optimized TiOx layer thickness of 4 nm provides high quality surface passivation, achieving minority carrier lifetime of 3.03 ms on 5 Ω cm n-type wafers, with a saturated current density J0 of 23 fA/cm2. In addition, inserting a 1 nm LiF between the 4 nm TiOx and Al reduces the contact resistivity to 18 mΩ cm2. The low contact resistivity of TiOx/LiF/Al contact is attributed to barrier reduction from the low work function of LiF/Al stack. A champion solar cell efficiency of 21.3% has been achieved for an n-type crystalline silicon device with a full-area rear TiOx/LiF/Al contact, demonstrating the excellent potential of this passivating contact for fabricating high-efficiency silicon solar cells.

Sistem Arus-Votan yang Murah dengan Rintangan Terkawal-Elektronik di bawah Lampu Xenon Arka untuk Pengukuran Kecekapan Sel Suria

Crystalline silicon solar cell efficiency is required in order to accurately determine its performance and evaluate the fabrication process. Extensive automation has led to development of expensive instrumentation. In this study, simple, inexpensive method for measuring solar cell efficiency is reported. A controllable direct current (dc) illumination intensity method based on low power xenon arc lamps was designed and constructed. Low resistance electrical contacts were formed with conventional front surface probes and back surface Au-plated metal plate with vacuum attachment. In order to measure current-voltage (I-V) response, variable resistance approach was chosen. Commercially available, low cost electronic loads power supply is used to precisely vary resistance while measuring cell voltage and current. The resistance is controllably varied from a short circuit to an open circuit position on the I-V curve while measuring cell voltage and current. Plotting current as a function of voltage generates the characteristic solar cell I-V response. Solar cell efficiency measurements were recorded and plotted using LabVIEW program. The light intensity was varied by increasing number of high intensity discharge (HID) 50 W from 1 to four in order to vary respective illumination intensities from 330 to 1200 W/m2 range. The variation in light intensity was aimed at investigation of the electronic loads power supply at low and high currents. This I-V tester has been applied to different types of solar cell to validate its performance. Solar cells measured as part of this study included commercial silicon solar cell and laboratory solar cells with phosphorus oxytrichloride (POCl3) and phosphoric acid (H3PO4) emitter formation. This I-V measurement system for commercial cell exhibited an efficiency of 15.83% and efficiency of 16.2% and 13.3% for solar cells with POCl3 and H3PO emitters.

Near-infrared emissions in host sensitized Ba2YV3O11: RE3+ (RE = Nd, Ho, Yb) down-converting phosphors

Nd3+/Ho3+/Yb3+ single-doped Ba2YV3O11 near infrared (NIR) emitting phosphors were produced using sol-gel route, and their structures were determined by X-ray diffraction (XRD). The down conversion spectra, luminescence lifetime and energy transfer (ET) efficiency of samples have been investigated, which indicate that Ba2YV3O11: Nd3+/Ho3+/Yb3+ phosphors offer intense broad absorption band (250–400 nm) and emit efficient 900–1100 nm NIR emission where the crystal silicon solar cells display the optimal response. The ET processes from [VO4]3- to dopants Nd3+/Ho3+/Yb3+ and possible ET mechanisms were also proposed in detail. Results showed that the Ba2YV3O11: Nd3+/Ho3+/Yb3+ phosphors were potential solar spectral converters for enhancing the silicon solar cell efficiency by absorption enhancement.

Enhancing the Performance of Textured Silicon Solar Cells by Combining Up-Conversion with Plasmonic Scattering

This paper experimentally demonstrates the benefits of combining an up-conversion (UC) layer containing Yb/Er-doped yttrium oxide-based phosphors with a plasmonic scattering layer containing indium nanoparticles (In-NPs) in enhancing the photovoltaic performance of textured silicon solar cells. The optical emissions of the Yb/Er-doped phosphors were characterized using photoluminescence measurements obtained at room temperature. Optical microscope images and photo current-voltage curves were used to characterize the UC emissions of Yb/Er-doped phosphors under illumination from a laser diode with a wavelength of 1550 nm. The plasmonic effects of In NPs were assessed in terms of absorbance and Raman scattering. The performance of the textured solar cells was evaluated in terms of optical reflectance, external quantum efficiency, and photovoltaic performance. The analysis was performed on cells with and without a UC layer containing Yb/Er-doped yttrium oxide-based phosphors of various concentrations. The analysis was also performed on cells with a UC layer in conjunction with a plasmonic scattering layer. The absolute conversion efficiency of the textured silicon solar cell with a combination of up-conversion and plasmonic-scattering layers (15.43%) exceeded that of the cell with an up-conversion layer only (14.94%) and that of the reference cell (14.45%).

Tunnel oxide passivating electron contacts for high‐efficiency n‐type silicon solar cells with amorphous silicon passivating hole contacts

AbstractThis study proposes a hybrid solar cell structure for a highly efficient silicon solar cell obtained by combining two passivating contact structures, namely, a heterojunction and polysilicon passivating contact. Given that the major cause of the loss in efficiency of crystalline silicon solar cells is carrier recombination at the metal‐semiconductor junction, a passivating contact having high‐quality passivation and a low contact resistance was introduced. In this study, two major passivating contact solar cells were combined. By applying an intrinsic thin amorphous silicon layer at the front and a tunneling oxide at the rear, a hybrid silicon solar cell with an efficiency of 21.8% was fabricated. Moreover, to evaluate the potential efficiency limit and to suggest methods for improving the cell performance of the proposed amorphous silicon emitter tunnel oxide back contact structure, the cell efficiency was simulated, and the result indicated that an efficiency of 26% could be achieved by controlling the thickness and resistivity of the wafer.

Performance of thin silicon solar cells with a quasi-monocrystalline porous silicon layer on the rear side

The present study employs porous silicon (PS) or quasi-monocrystalline porous silicon (QMPS) as a reflector material on the rear side. It presents an analytical model that simulates the performance of n+–p–p+ thin silicon solar cell with a QMPS layer on the rear side. The development of the model involves the formulation of a complete set of equations for the photocurrent density that is then solved analytically in the base region, including the photocurrent generated under the effect of the light reflected by QMPS layer. This also takes the contribution of the back p+-region (back surface field) to the generated photocurrent into consideration. The enhancements brought by the thin film QMPS with regard to photovoltaic (PV) parameters are then investigated and compared to those brought by the conventional silicon solar cell. Moreover, the effect of the QMPS layer on the current–voltage characteristics J–V and the internal quantum efficiency (IQE) of thin silicon solar cells are simulated by means of AFORS-HET software. These simulations show that the improvement of the PV parameters is due to an increase in the transport parameters of minority carriers in the p-region.

Computational modelling of monolithically stacked perovskite/silicon tandem solar cells using monofacial and bifacial designs

As the efficiency of conventional silicon (Si) solar cell is reaching closer to its thermodynamic limit, its tandem integration with emerging perovskite (PVK) solar cell is being widely explored. In this work, we use self-consistent optical and electrical simulations to computationally explore monolithically stacked 2-terminal (2-T), 2-junction (2-J) PVK/Si tandem solar cell. The optical model is based on Lambert-Beer Law while electrical model is based on drift-diffusion approach. The tandem solar cell is explored for both monofacial and bifacial configurations. The simulations show that the cell design for optimal operations is highly dependent on perovskite thickness and albedo. Under optimal design, the bifacial PVK/Si tandem cell exhibits ∼32.5% for average earth albedo of 30%. Moreover, the cell exhibits a remarkable temperature coefficient of ∼-0.27%. Moreover, our simulation results are in good agreement with both experimental and highly intensive optical model based simulation data. With our computationally inexpensive optical model, the optimal cell design for different tandem structures can be explored in a much easier way.

Anodic oxidations: Excellent process durability and surface passivation for high efficiency silicon solar cells

We investigate the versatility of anodically grown silicon dioxide (SiO2) films in the context of process durability and exceptional surface passivation for high efficiency (>23%) silicon solar cell architectures. We show that a room temperature anodic oxidation can achieve a thickness of ~70 nm within ~30 min, comparable to the growth rate of a thermal oxide at 1000 °C. We demonstrate that anodic SiO2 films can mask against wet chemical silicon etching and high temperature phosphorus diffusions, thereby permitting a low thermal budget method to form patterned structures. We investigate the saturation current density J0 of anodic SiO2/silicon nitride stacks on phosphorus diffused and undiffused silicon and show that a J0 of <10 fA cm−2 can be achieved in both cases. Finally, to showcase the anodic SiO2 films on a device level, we employed the anodic SiO2/silicon nitride stack to passivate the rear surface of an interdigitated back contact solar cell, achieving an efficiency of 23.8%.

Annihilating Pores in the Desired Layer of a Porous Silicon Bilayer with Different Porosities for Layer Transfer

A silicon layer that is tens of micrometers thick on a handle substrate is desired for applications involving power devices, microelectromechanical systems (MEMS), highly efficient silicon solar cells (<50 µm), etc. In general, if the initial silicon layer obtained from the layer transfer process using the etch-stop or ion-cut techniques, which may provide very accurate thickness control, is too thin, then additional epitaxial growth is required to increase the thickness of the silicon layer. However, epitaxial growth under strict predeposition conditions is a time-consuming and expensive process. On the other hand, producing porous silicon via anodization in a hydrofluoric acid solution offers an efficient way to control the dimensions of the generated pores directly on the nano- or macroscale via the current density. When sintering the porous layer via high-temperature argon annealing, the porosity of the porous layer determines whether this porous layer can serve as a device layer or a separation layer. In addition, it is clearly easier to create a transferred layer ten of micrometers thick via anodization than by ion implantation and/or epitaxial deposition.

Development of sol-gel derived gahnite anti-reflection coating for augmenting the power conversion efficiency of polycrystalline silicon solar cells

Abstract The present research is focused on developing ZnAl2O4 (gahnite) spinel as an antireflection coating material for enhanced energy conversion of polycrystalline silicon solar cells (PSSC). ZnAl2O4 has been synthesized using dual precursors, namely aluminum nitrate nonahydrate and zinc nitrate hexahydrate in ethanol media. Diethanolamine has been used as a sol stabilizer in sol-gel process for ZnAl2O4 nanosheet fabrication. ZnAl2O4 nanosheet was deposited layer-by-layer (LBL) on PSSC by spin coating method. The effect of ZnAl2O4 coating on the physical, electrical, optical properties and temperature distribution in PSSC was investigated. The synthesized antireflection coating (ARC) material bears gahnite (ZnAl2O4) spinel crystal structure composed of two dimensional (2D) nanosheets. An increase in layer thickness proves the LBL deposition of ARC on the PSSC substrate. The ZnAl2O4 2D nanosheet comprising ARC on the PSSC was tested and it exhibited a maximum of 93 % transmittance, short-circuit photocurrent of 42.364 mA/cm2 and maximum power conversion efficiency (PCE) 23.42 % at a low cell temperature (50.2 °C) for three-layer ARC, while the reference cell exhibited 33.518 mA/cm2, 15.74 % and 59.1 °C, respectively. Based on the results, ZnAl2O4 2D nanosheets have been proven as an appropriate ARC material for increasing the PCE of PSSC.

Reducing parasitic absorption and recombination losses in silicon solar cells through transition metal doped glass frit

Efficient electron selective contacts, smoother rear silicon surface and passivation of silicon-electrode interfaces could reduce parasitic light absorption and electron-hole recombination. Therefore, they are necessary for high conversion efficiency in silicon solar cells. In this work, a novel transition metal doped glass frit is fabricated and introduced into pristine Al paste. As a result, the average power conversion efficiency (PCE) of cells is improved from 17.9 to 18.3%. Combining several results, the improvement can be attributed to three key factors: (a) a thicker back surface field (BSF) layer that blocks electrons; (b) a smoother rear silicon surface which leads to less parasitic absorption; and (c) glass frit coating on aluminum particles which may facilite hole-transfer from silicon layer to aluminum electrode.

Synthesis of Si and CdTe quantum dots and their combined use as down-shifting photoluminescent centers in Si solar cells

This paper describes the synthesis and characterization of Si and CdTe quantum dots (QDs) and their use, either on their own or combined, as photoluminescent (PL) down-shifting nanostructured coatings aimed to enhance the photovoltaic efficiency of polycrystalline silicon solar cells. To this end, the front face of a set of silicon cells was coated with different volume ratios of the above-mentioned QDs, or some of its mixtures, dispersed in PMMA layers. Previously, the absorption and the PL (exc = 380 nm) response of the dispersions of the QDs were measured. It was observed that the PL response of the mixtures was strongly affected in location, spread, and intensity of the emission peak according to the volume ratio involved. As compared to the unmixed CdTe samples, a notorious red-shift of the main peak location was obtained for a couple of mixed QDs’ dispersions, which was one of the project objectives given that Si solar cells respond better to photons with wavelengths in the 650–700 nm range. This effect was confirmed in a set of polycrystalline Si solar cells covered with and without nanostructured PMMA/QDs layers tested under AM 1.5G solar simulator conditions. It was found that the use of the proposed mixtures of QDs gave an increase of 1.53% in solar cell power conversion efficiency.

Investigation of quasi-periodic structures to increase the efficiency of thin-film silicon solar cells: A comparative study

To boost the energy conversion efficiency in a thin-film Si solar cell, the effect of applying simple and generalized Fibonacci and Thue-Morse quasi-periodic multilayers in the front and back sides have been investigated. The anti-reflection coating and the back reflector are composed of SiO2/TiO2 and SiO2/Si sequences, respectively and the obtained results are in a good agreement with previous studies. Also, a 2D square array photonic crystal with 12-fold basis has been introduced to enhance the optical path length and hence, the absorption probability for longer wavelengths due to excitation of higher-order diffraction modes. The study has been carried out using the transfer matrix method (TMM) and the finite difference time domain (FDTD) methods and the electrical characteristics have been obtained implementing the drift-diffusion. A reasonable enhancement of ~115% and more than 120% in the short circuit current density and conversion efficiency have been achieved, respectively in the optimized structure.

Applications of rare earth Tb3+-Yb3+ co-doped down-conversion materials for solar cells

We prepared Tb3+-Yb3+ co-doped silicate glass as a down-conversion layer and used it in solar cells. We confirmed the existence of a down-conversion process in the system by absorption spectroscopy, fluorescence spectroscopy and energy level analysis. Tb3+ ions can absorb high-energy photons and effectively pass the energy to Yb3+ ions. Then Yb3+ ions emit near-infrared photons with energies that match monocrystalline silicon solar cells. As the Yb3+ ion concentration constantly changed, the energy transfer efficiency and the photoelectric conversion efficiency of solar cells both changed. We measured in the standard environment (AM1.5G) and found that Tb3+-Yb3+ co-doped silicate glass samples can improve the photoelectric conversion efficiency of monocrystalline silicon solar cells by 8.6%. Our results show that this material has great potential in the application of solar cells.

Microwave-assisted Fe-doped ZnO nanoparticles for enhancement of silicon solar cell efficiency

We have investigated the performance of a silicon solar cell coated with ZnO nanoparticle layers doped with iron varying from (0–20%). We synthesized nanoparticles using a microwave method and fabricated thin film layers on silicon solar cells through a spin coating technique. The structure and morphology of nanoparticles were analyzed through transmission electron microscopy (TEM) and X-ray diffraction spectroscopy (XRD). The size of the particles decreased as iron concentration increased from 0 to 15%. Optical properties were analyzed through photoluminescence (PL) and absorption spectroscopy. PL spectra show a blueshift in the near band edge emission peaks for 0–15% doped samples and a redshift for the 20% doped sample. The band gap of Fe–ZnO nanoparticles (0–15%) was found to increase from 3.20 eV to 3.24 eV, and the bandgap decreased to 3.22 eV for 20% Fe–ZnO nanoparticles. Current-Voltage measurements confirm the enhancement in power conversion efficiency by 30% with iron doping in ZnO up to 15%. Efficiency increased with nanoparticle layers up to 180.29 nm in every sample and decreased with further increase in thickness. Enhancement in external quantum efficiency (EQE) was also observed with the increase in dopant concentration up to 15%. The optimum thickness of the ZnO nanoparticle layer was found to be approximately 180 nm for maximum enhancement in conversion efficiency.