Amorphous Silicon Solar Cells Research Articles

Study of ultrathin‐film amorphous silicon solar cell performance using photonic and plasmonic nanostructure

The photonic and plasmonic nanostructures are highly feasible for enhanced light trapping mechanisms. These nanostructures hold great promises for better photovoltaic performance by yielding the highest light-harvesting photons within the few nanometer absorber regions. The shed light on the nano-scaled structures (thin films and nanogratings) is responsible for the highest scattering mechanism with the omnidirectional diffraction angles and enhanced life time of the photons. In this research work, we have focused on improved ultrathin film amorphous silicon (a-Si) solar cell performance, which was integrated by top-SiO2 and bottom-Ag nanogratings as a backside reflector by using rigorous coupled-wave analysis method. The SiO2 antireflection coating, nanogratings, and absorber (a-Si) layer thicknesses were optimized for better photovoltaic performance. With the influence of optimization parameters, the highest current density of 27.03 and 33.53 mA/cm2 were obtained from transverse electric and transverse magnetic polarization conditions due to the surface guided-mode, Fabry–Perot resonance, surface excitation, localized fields, and surface plasmon polariton modes.

Photovoltaic distribution on an amorphous-silicon solar cell in near-band-edge excitation observed by conductive-probe atomic force microscopy combined with a fine-wavelength-tunable light source.

We describe the development of a conductive-probe atomic force microscopy method combined with a fine-wavelength-tunable light source and use it to observe the photovoltaic distribution on a cross-sectional surface of an amorphous-silicon solar cell in near-band-edge excitation. The light source's wavelength resolution is dλ = 1nm, and its intensity is 1 µW/cm2 (10 mW/m2); this excitation condition is sufficiently fine and weak to investigate electrical properties in the near-band-edge wavelength range. The photovoltage is observed in the indium tin oxide (ITO) region, and the maximum photovoltage increases when we increase the excitation energy of the illumination light. However, the photovoltaic distribution parallel to the ITO layer becomes relatively localized as the excitation energy increases. This localized photovoltaic distribution suggests that the conductivity of the electric current path within the ITO layer should be inhomogeneous.

Simple and efficient design towards a significant improvement of the optical absorption of amorphous silicon solar cell

In recent times, solar cell presents a good candidate for solving the problems of energy crisis and environmental pollution as well. However, it could suffer from the limited absorption among the full spectral wavelength. In this context, we present in this paper a simple and efficient design towards a prominent enhancement of the optical characteristics of amorphous silicon solar cells. Here, we have theoretically demonstrated the role of the one-dimensional photonic crystals as an anti-reflecting coating and back reflector to improve the absorption properties of the proposed cell. The anti-reflecting coating is designed from a single period of the one-dimensional quadrant photonic crystals. Whilst 10 periods of the one dimensional binary photonic crystals are used to design the back reflecting mirror. The theoretical framework of our study is mainly based on the finite element method and the transfer matrix method as well. The investigated results verify the significant role of the anti-reflecting coating and the back mirror in raising the absorption values of the cell that could reach over than 0.9 in the wavelength domain from 350 nm to 640 nm. Moreover, the change in the values of the angle of incidence investigates a distinct decrease in spectral absorption.

A Numerical Modeling on Light I-V Curves of Hetero-Junction Amorphous Silicon Solar Cells

A Numerical Modeling on Light I-V Curves of Hetero-Junction Amorphous Silicon Solar Cells

A high gain solar cell aperture‐coupled patch antenna based on substrate‐integrated suspended line platform for 5G application

AbstractThe aperture‐coupled patch antenna integrated with the amorphous silicon solar cell based on the substrate‐integrated suspended line platform is presented in this letter. The antenna patch on G1 layer is used as the cathode of amorphous silicon cell and the 1 × 2 array antenna is proposed based on the unit. The solar cell antenna operating from 4.67 to 5.17 GHz has the characteristic of high gain, which is achieved by air coupling to reduce loss. The gain of the unit and array is 9.21 and 11.92 dBi, respectively. In addition, the results of the antennas with and without solar cells are little different.

Effects of Back-Reflectors on a-Si: H Solar Cells

ZAO (ZnO: Al)/Al and ITO/Ag complex back-reflectors were successfully applied to substrate nip and superstrate pin amorphous silicon solar cells respectively. As a result, the short circuit current (Isc) for a cell with a complex back-reflector increases significantly as compared with a cell without a complex back-reflector. For a superstrate pin cell prepared on SnO2 coated glass, the short-circuit current even increases up to 30%.

Coupled optical-electrical-thermal simulation for nanoparticles enhanced armorphous silicon solar cells

This paper strives to provide a better insight regarding the thermal impact on an amorphous silicon solar cell embedded with silver nanoparticles. Investigation on thermal influence is carried out through simulation modelling. The main aspects considered in modelling are optical, electrical and thermal aspects. The more holistic modelling treatment in this paper introduces various feedback links among three main aspects. Besides thermal impact, this paper provides a preliminary analysis on the factor hindering the nanoparticles embedded from providing satisfactory enhancement on conversion efficiency. The simulation shows that a rise in cell temperature within a range of 32.44K lowers the electrical performance of the cell but promotes a better optical absorption. However, the variations introduced by the rise in temperature are less significant within the simulated temperature range. The key factor that hinders the potential of the nanoparticles lies in the enhanced light spectrum (longer wavelength region).

Approximation of photovoltaic characteristics curves using Bézier Curve

Accuracy of solar cell model parameters is now a requirement for the manufacturing of appropriate photovoltaic models. Consequently, the methodologies of the parameters had already attracted immense interest among researchers over the years. This paper deals about the approximation of the characteristics curves of a solar cell using the Bézier curve method. This technique is selected to overcome the problems of the non-linearity, complexity, multivariate and multimodal of the characteristic's curves. The Bézier curves method is a parametric curve used throughout computer graphics and related disciplines. It is a robust methodology for constructing free-form curves, surfaces, shape design, and geometric representation of various products. Six different cases are carried out to test the validity of the proposed method, they are: (i) organic flexible dual junction amorphous silicon solar cell, (ii) silicon solar cell, (iii) Schutten Solar STP6-120/36 polycrystalline photovoltaic module, (iv) Schutten Solar STM6-40/36 monocrystalline photovoltaic module, (v) Photowatt-PWP 201 polycrystalline photovoltaic module and (vi) 230-W multi-silicon photovoltaic module under partial shading conditions. The technique is implemented and adapted by the mean of the De Casteljo algorithm to optimize the control points and minimize the distance between the experimental and calculated points. It is based on subdividing the curve into various segments and controlled by control points using the De Casteljo algorithm to minimize the distance between the experimental and theoretical points. The performance of the approximated characteristics curves is compared with experimental data as well as recent algorithms and techniques from the literature. For more validity, statistical error metrics from literature are computed and compared to ensure the accuracy of the approximated results and the performance of the proposed method. For instance, the comparison is carried out by resorting to the Individual Absolute Error (IAE) and the Relative Error (RE). Further, the Bias metrics and accuracy are calculated using the Autocorrelation Function (ACF), Tracking Signal (TS), and Normalized Forecast Metric (NFM). The proposed method provides a low error for the six case studies and better than that obtained by the other algorithms.

Solar photovoltaic technology: A review of different types of solar cells and its future trends

The Sun is source of abundant energy. We are getting large amount of energy from the Sun out of which only a small portion is utilized. Sunlight reaching to Earth’s surface has potential to fulfill all our ever increasing energy demands. Solar Photovoltaic technology deals with conversion of incident sunlight energy into electrical energy. Solar cells fabricated from Silicon aie the first generation solar cells. It was studied that more improvement is needed for large absorption of incident sunlight and increase in efficiency of solar cells. Thin film technology and amorphous Silicon solar cells were further developed to meet these conditions. In this review, we have studied a progressive advancement in Solar cell technology from first generation solar cells to Dye sensitized solar cells, Quantum dot solar cells and some recent technologies. This article also discuss about future trends of these different generation solar cell technologies and their scope to establish Solar cell technology.

A Parametric Study of Coupled Photo-Electro-Thermal Responses of Thin Film a-Si:H Solar Cell with Embedded Nanoparticles

A parametric investigation has been performed on a thin-film hydrogenated amorphous silicon (a-Si:H) solar cell that is enhanced with various light trapping schemes through a modelling approach. The proposed model contains a novel coupling approach and various feedback routines for a more holistic modelling treatment. The proposed optical model adopts a semi-coherent method, the electrical model extends the classical drift-diffusion model to incorporate the effects of thermal gradients, and the thermal model adopts energy conservation equations from the hydrodynamic model. Based on the simulation results, it is observed that the rise in cell temperature adversely affects the electrical performance but promotes more optical absorptions due to the unique optical properties of amorphous silicon. To obtain an optimum enhancement from the inclusion of nanoparticles, their dimensions and separation distances are essential factors. The thickness of the intrinsic active absorbing layer affects the optical performance directly which then leads to various variations in electrical and thermal responses.

Crystalline Silicon vs. Amorphous Silicon: the Significance of Structural Differences in Photovoltaic Applications

Firstly, the paper briefly introduces the structure of crystalline silicon, amorphous silicon, and hydrogenated amorphous silicon and highlights the structural differences. Then, the paper presents a feature-by-feature based comparison between c-Si solar cells and a-Si solar cells. What roles different structures of silicon play in each PV characteristic are subsequently explored. In the end, based on these previously analyzed features, this paper further discusses circumstances in which the use of either c-Si or a-Si solar cells may be appropriate, the use of c-Si solar cells is more appropriate, and the use of a-Si solar cells is more appropriate. In short, the outstanding conversion efficiency and user-friendly cost of crystalline silicon solar cells prove successful, while the disturbing nature of amorphous silicon solar cells demonstrates several optical and electrical properties, like high absorption coefficient and Staebler-Wronski Effect, never before anticipated.

Resonant nano-dimer metasurface for ultra-thin a-Si:H solar cells

Low-cost hydrogenated amorphous silicon solar cells (a-Si:H) can perform better and be more competitive by including nanostructures. An optimized nano-dimer structure embedded in close contact with the back electrode of an aSi:H ultra-thin solar cells can enhance the deliverable short-circuit current up to 27.5 %. This enhancement is the result of an increase in the absorption at the active layer, that is the product of an efficient scattering from the nanostructure. From our calculations, the nano-dimer structure must be made out of a high-index of refraction material, like GaP. The evaluation of the scattering and absorption cross section of the structure supports the calculated enhancement in short-circuit current, that is always accompanied by a decrease in the total reflectance of the cell, which is reduced by about 50 %.

The benefit of using p-a-SiOxCy:H as double window layers in hydrogenated amorphous silicon solar cells: Correlation of simulation and experiment

By using AMPS-1D simulation program, we have simulated and compared two experimental p-i-n devices. One with p-type window and buffer layers based on hydrogenated amorphous silicon oxide (p-a-SiOx:H) and the other with two p-a-SiOxCy:H layers based on hydrogenated amorphous silicon oxycarbide.The numerical results showed that, an incorporation of the p-a-SiOxCy:H layer instead of the p-a-SiOx:H layer, as window layer reduces the value of holes front contact barrier height (φh) and as buffer layer leads to a smaller values of conduction band (ΔEC) and valence band (ΔEV) offsets. In one hand, the ΔEV low value minimizes the recombination of photogenerated holes at the i/p interface. In the other hand, low value of holes front contact barrier height (φh) obtained with using p-a-SiOxCy:H layer, facilitates to a large amount of photogenerated holes to reach the interface of the front contact. It is also obtained that, the integration of p-a-SiOxCy:H double window layer i improves the short circuit-current density (JSC) which is causes by a good spectral response in the short wavelength. Consequently, an enhancement in the efficiency of the p-i-n single junction device was obtained and we could achieve the value of 10.7 %. This result makes the oxycarbide p-a-SiOxCy:H films which have wider band gap, lower absorption coefficient and good conductive properties more suitable for using as window and buffer layer in a-Si:H based solar cells.

Sensor and photovoltaic dual functions of a-Si:H solar cell in smart clothing and eyewear

PurposeFlexible hydrogenated amorphous silicon (a-Si:H) solar cells have many advantages, including lower weight, good flexibility and light sensitivity. Moreover, a-Si:H solar cells can be used as sensors, as indoor light sources and can also generate electricity. These solar cells are suitable for the design of portable systems and curved materials. The purpose of this study was to integrate flexible a-Si:H solar cells and wearable technology and to apply the dual functions of photovoltaics and photo sensors to smart clothing and eyewear.Design/methodology/approachThe integration of flexible a-Si:H solar cells and tri-colour light-emitting diodes (LEDs) was used to develop smart auto-flashing clothing. In addition, we combined flexible a-Si:H solar cells and twisted nematic (TN) liquid crystal (LC) cells to design smart self-activation eyewear.FindingsThe maximum power resistance value of flexible a-Si:H solar cells was used to deduce the equation of solar cell voltage value generated by different percentages of SUN (100% SUN means 100 mW/cm2). A solar cell was used as a photo sensor that connects a resistor in a series to the Arduino to detect the voltage value, and then different percentages of SUN are calculated from the equation. Applying the deduced equation to the smart phone APP and Arduino code, we developed a human–machine interface (HMI) to facilitate user operation.Originality/valueIn this study, the flexible a-Si:H solar cell performs the function of not only photovoltaic power generation but also that of a photo sensor. The smart auto-flashing clothing is suitable for traffic guides, joggers and people engaging in other night activities. This smart self-activating eyewear can adjust to light and protect the eyes.

Aluminium nanoparticles alloyed with other earth-abundant plasmonic metals for light trapping in thin-film a-Si solar cells

Plasmonic nanoparticles have been used for a variety of applications, including light trapping in thin film solar cells. Due to costs associated with the most commonly studied plasmonic metals (Au and Ag), other metals such as Al, In, Mg and Ni have recently emerged as alternative, earth-abundant plasmonic metals. Though the plasmonic properties of these metals have been studied individually (particularly Al) there have been few reports on the plasmonic properties of alloys of earth-abundant plasmonic metals. This is of interest because alloying could offer a degree of plasmonic tunability, improved corrosion resistance and drive down costs. In this report we study the light trapping ability of Al–Cu, Al–Au, Al–Ni, Al–In and Al–Mg alloys in an amorphous silicon solar cell. We use a combination of Mie Theory, Transfer Matrix Modelling and Effective Medium Theory to develop a simple numerical solution to this problem, and benchmark it against known theoretical results. Al–In and Al–Mg alloy nanoparticles emerge as the most suitable (of the candidates studied) for this application. Al (75%) In (25%) (by volume fraction) nanoparticles of radius 15 nm are shown to improve the absorption of amorphous silicon by 18%. We provide maps of the plasmonic behaviour of alloy nanoparticles for a range of radii (1-100 nm) and alloy compositions, enabling materials design. Therefore, we hope that this report will spur further interest into the utility of Al-alloy nanoparticles for plasmonic applications.

Shunt resistance spatial variations in amorphous silicon solar cells

This article describes the spatial variations of the shunt resistance in a-Si:H, PV cells across the absorber layer (i-layer). When the a-Si:H PV cell is illuminated through its front layer, photo generated carriers distribute along the i-layer as a function of the radiation WL and the voltage drop across the PV cell. The generated electric currents of the electrons and holes are simultaneously determined by solving the equations of the transport, Poisson, and the continuity as a role of the voltage and the place near the i-layer. In this work, leakage flow of electrons and holes is calculated through the i-layer to calculate the corresponding two J/V curves of the two carrier types. Therefore, the shunt resistance associated to each carrier type varies is calculated separately and will be variable overall the i-layer. This research bring out with the calculation of area dependent shunt resistance extracted from the location-dependent J/V curves of the carriers is comparable to the conventional single valued shunt resistance found from the global J/V curve of the PV cell. This proposed work is a novel idea, which clearly indicates the simple technique to calculate shunt resistance spatial variations of a-Si:H PV cell. This article also presents the impact of the CM values on the calculated shunt resistance of the PV cells.

Interfacial assessment of degraded amorphous silicon module using scanning probe microscopy

This is a study of the degradation of amorphous silicon solar cells. The study accessed structural defects and the mechanical stress of solar cells at nanoscale level. Interface morphology, deformation, and internal delamination of the cells were analyzed. Adequate analysis of roughness parameters was performed to investigate the state of degradation of the amorphous silicon solar modules (a-Si:H) used in this study. Roughness parametric test is necessary in thin film solar cells production process because it is used to quantify the relationship that exists between roughness parameters and electrical efficiencies of solar cells. However, in this study, a roughness analysis was not only performed to quantify the performance of the a-Si:H module but to also compliment their mechanical degradation analysis. Roughness indicators such as root means square (RMS) roughness and average roughness were acquired from line profiles. Measurements were taken with scanning probe microscope (SPM) and PeakForce Quantitative Nanomechanical (QNM) technique was used through the cross sectional area of the analyzed samples. The method was validated with adhesive force and deformation analyses; it was established that high roughness values result from mechanical degradation. Results from the roughness parameters and the mechanical degradation analysis were further observed from in situ measurements and these showed good compatibility. The benefit of this technique is that it provides a good procedure for the evaluation of mechanical degradation without destroying any part of the intrinsic layers in a-Si:H modules.

Comparative study on energy and exergy properties of solar photovoltaic/thermal air collector based on amorphous silicon cells

This paper compared the performance of solar photovoltaic/thermal (PV/T) air collectors (SPVTAC) based on amorphous silicon solar cells with traditional solar air collectors and individual photovoltaic (PV) modules. The SPVTAC was proposed to overcome the problems of large thermal stresses at fluctuating temperatures and frost in winter, and also due to their working suitability in medium–high temperature ranges. The energy and exergy performance of the three devices were tested and analyzed with different airflow rates, inlet temperatures and solar irradiance. The experimental results show that the thermal efficiency of SPVTAC was approximately 25% lower than the traditional solar air collector at the same operating condition. Also, the electrical efficiency of SPVTAC was higher than the individual PV system (4.65%) when the air mass flow rate was over 0.040 kg/s. For each degree increase in the inlet temperature, the thermal efficiency of the amorphous silicon SPVTAC decreased by approximately 0.45%, the electrical efficiency decreased by approximately 0.042% and the temperature difference between the inlet and outlet decreased by 0.24 °C. The maximum total exergy efficiency of the SPVTAC (12.22%) and the maximum thermal exergy efficiency of the traditional solar air collector (8.71%) was achieved at an inlet air temperature of 60 °C. These experimental results provide a reference for further applications of amorphous silicon solar cells integrated with SPVTAC.

Enhanced Conversion Efficiency of a-Si:H Thin-Film Solar Cell Using ZnO Nanorods

The surface reflectivity of a material will vary as light passes through interfaces with different refractive indices. Therefore, the optical loss and reflection of an optical-electronic component can be reduced by fabricating nanostructures on its surface. In the case of a solar cell, the presence of nanostructures can deliver many different advantages, such as decreasing the surface reflectivity, enhancing the light trapping, and increasing the efficiency of the carrier collection by providing a shorter diffusion distance for the photogenerated minority carriers. In this study, an approximately 50-nm thick seed layer was first prepared using spin coating. Zinc oxide nanorods (ZnO-NRs) were then grown using a chemical solution method (CSM). The ZnO-NRs were approximately 2 μm in height and 100 nm in diameter. After applying them to amorphous silicon (a-Si:H) solar cells, the short-circuit current density increased from 8.03 to 9.24 mA/cm2, and the photovoltaic conversion efficiency increased by 11.24%.

Photon management of combining nanostructural antireflection and perovskite down-shifting composite films for improving the efficiency of silicon solar cells

Photon management is an efficient route to ameliorate optical issues for improving the efficiency of solar cells. On account of reflection loss and spectral mismatch for silicon solar cells, we herein firstly demonstrate a photon management of combining antireflection and luminescence down-shifting coatings to simultaneously suppress the reflection of incident light with nanoporous structure and improve the spectra response of silicon solar cells in short wavelength with in-situ fabricated perovskite quantum dots composite film. Antireflection film can be obtained by sacrificing CdxZn1-xSeyS1-y/ZnS quantum dots template in PDMS composite film, which can bring 9.7% improvement in photocurrent for amorphous silicon solar cells. By further combining perovskite quantum dots down-shifting luminescence coating, an absolute improvement of 1.05% in power conversion efficiency was achieved. The photon management combining the antireflection and luminescence down-shifting coatings could provide a low-cost, simple but effective way to address the optical issues and improve the device performance of optoelectronic devices.