Electrical Properties Of Solar Cells Research Articles

Effect of bandgap variation on photovoltaic properties of lead sulfide quantum dot solar cell

The tunable bandgap of quantum dot (QD)-based solar cells is their greatest advantage, providing control over light absorption region. However, the investigation of the effect of bandgap variation on QD-based photovoltaic properties is insufficient, in contrast to well-defined material properties. In this study, we analyze the electrical properties of solar cells fabricated with bandgap-tuned lead sulfide (PbS) QDs to examine the effect of bandgap variation on photovoltaic properties. We find that reducing the thickness of the QD active layer is necessary to achieve high power conversion efficiency mainly because the doping concentration of the QD film increases as the QD bandgap decreases. We suggest that QD photovoltaic device structures should be designed with consideration of their electrical characteristics in relation to the bandgap.

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.

Influence of Silicon Dioxide-Titanium Dioxide Antireflective Electrosprayed Coatings on Multicrystalline Silicon Cells

This research work primarily focuses on enhancing the power conversion efficiency (PCE) of polycrystalline silicon solar cells by using a single-layer and a double-layered antireflection coating deposited through the electrospraying technique. The usage of titanium dioxide and silicon dioxide as antireflection coating materials has shown a significant increase in the optical and electrical properties of solar cells under open and controlled light sources. The sample with TiO2 as a base layer and SiO2 as the top layer (sample B-IV) exhibited a maximum PCE of 18.90% in direct sunlight and 21.19% in a neodymium setup with cell temperatures of 40°C and 52.1°C, respectively. Sample B-IV has also shown the lowest resistivity of 3.1 × 10−3 Ω·cm among the coated samples. Also, an increase of 11.6% light transmittance and a reduction of 9.6% light reflectance were exerted by sample B-IV. The results obtained from different analysis proves that TiO2/SiO2 was an appropriate antireflection coating material for enhancing the PCE of the polycrystalline silicon solar cell.

Enhancement of the conversion efficiency of selective emitter PERC solar cells by post-oxidation

Thermal oxidation has been widely adopted in the fabrication process of silicon solar cells. In this paper, we investigate the effect of thermal oxidation on the performance of passivated emitter and rear cells (PERC) after the diffusion process. It is found that the application of a diffusion furnace for post-oxidation results in the re-doping of phosphorus, which affects the minority carrier lifetime and implied Voc. In comparison, the use of an annealing furnace for post-oxidation brings an improvement of electrical properties of solar cells because of the gettering effect. Furthermore, the increase in thickness of the oxide layer mitigates the laser-induced damage during the laser doping process, which is beneficial for the enhancement of cell efficiency. Batch data shows that post-oxidation using an annealing furnace leads to an absolute efficiency improvement by 0.1%.

Modification of a standard Al-BSF solar cell line into PERC using PECVD

This study is devoted to comprehensive study of the physical and electrical properties of solar cells manufactured on the basis of the Kazakhstan multicrystalline silicon of solar grade (SoG-Si). The study applied: 4-point resistance measurement method, a method of microwave detected photoconductive decay (?-PCD), a method of Light Beam Induced Current (LBIC), methods for spectrometric analysis of reflection, transmission and photoluminescence coefficients, scanning electron microscopy, and methods for analyzing current-voltage characteristics. The batches of Al-BSF and PERC photovoltaic converters based on Kazakhstani silicon were manufactured and analyzed. To improve efficiency, the study proposes a modification of a standard Al-BSF production line to a PERC line using PECVD. Keywords: solar cell, silicon, efficiency, Al-BSF, PERC, solar cell production, PECVD.

Модификация стандартной производственной линии Al-BSF фотоэлектрических преобразователей до PERC с использованием PECVD

This study is devoted to comprehensive study of the physical and electrical properties of solar cells manufactured on the basis of the Kazakhstan multicrystalline silicon of solar grade (SoG-Si). The study applied: 4-point resistance measurement method, a method of microwave detected photoconductive decay (μ-PCD), a method of Light Beam Induced Current (LBIC), methods for spectrometric analysis of reflection, transmission and photoluminescence coefficients, scanning electron microscopy, and methods for analyzing current-voltage characteristics. The batches of Al-BSF and PERC photovoltaic converters based on Kazakhstani silicon were manufactured and analyzed. To improve efficiency, the study proposes a modification of a standard Al-BSF production line to a PERC line using PECVD.

Enhancement of Schottky Junction Silicon Solar Cell with CdSe/ZnS Quantum Dots Decorated Metal Nanostructures

Recently, in the solar energy society, several key technologies have been reported to meet a grid parity, such as cost-efficient materials, simple processes, and designs. Among them, the assistive plasmonic of metal nanoparticles (MNPs) integrating with the downshifting on luminescent materials attracts much attention. Hereby, Si-based Schottky junction solar cells are fabricated and examined to enhance the performance. CdSe/ZnS quantum dots (QDs) with different gold nanoparticles (Au NPs) sizes were incorporated on a Si light absorbing layer. Due to the light scattering effect from plasmonic resonance, the sole Au NPs layer results in the overall enhancement of Si solar cell’s efficiency in the visible spectrum. However, the back-scattering and high reflectance of Au NPs lead to efficiency loss in the UV region. Therefore, the QDs layer acting as a luminescent downshifter is deployed for further efficiency enhancement. The QDs layer absorbs high-energy photons and re-emits lower energy photons in 528 nm of wavelength. Such a downshift layer can enhance the overall efficiency of Si solar cells due to poor intrinsic spectral response in the UV region. The optical properties of Au NPs and CdSe QDs, along with the electrical properties of solar cells in combination with Au/QD layers, are studied in depth. Moreover, the influence of Au NPs size on the solar cell performance has been investigated. Upon decreasing the diameters of Au NPs, the blueshift of absorbance has been observed, cooperating with QDs, which leads to the improvement of the quantum efficiency in the broadband of the solar spectrum.

Mechanism investigation on effects of glass composition on Ag/Si contact for crystalline silicon solar cells

Pb–Te–Li oxide glasses have been widely applied in front silver (Ag) paste metallization of crystalline silicon (c-Si) solar cells. In practical application, some other important glass compositions, such Bi2O3, SiO2, ZnO and so on, are often added into Pb–Te–Li oxide glasses to improve the quality of Ag/Si contact. In this paper, the significant effects of these glass compositions on the Ag/Si contact are demonstrated by discussing their influences on the formation of Ag colloids in the interface, the erosion of glass to Si, the glass phase conductivity, and the glass passivation performance at the contact interface. The results show that the addition of Bi2O3 or SiO2 into the glass may reduce the Ag/Si contact resistivity, because Bi2O3 can promote the formation of Ag colloid in the interface glass layer and increase the interface glass phase conductivity, and SiO2 can weaken the erosion ability of the glass to keep relatively high dopant concentration in the contacted Si surface. The addition of ZnO into the glass may aggravate the erosion to Si and decrease the glass phase conductivity. It is inferred that increasing Bi2O3 and SiO2 or reducing ZnO can improve the glass passivation performance at the contact interface. Through the application in Ag paste metallization, the important effects of the glass compositions on the electrical properties of solar cells are shown that Bi2O3 and SiO2 in the glasses are helpful to increase the open-circuit voltage and short-circuit current, while ZnO is very useful for raising fill factor.

Preparing Cu2ZnSnSe4 thin film solar cells based on selenium containing precursors

Abstract Selenium containing precursors were prepared by magnetron sputtering SnSe, ZnSe and Cu targets. Effects of different annealing temperature on performances of Cu2ZnSnSe4(CZTSe) thin film and solar cells were investigated. CZTSe absorber layers based on selenium containing precursors were obtained using different selenization temperatures. The crystal structure, phase purity, surface and cross section morphologies and the element compositions of CZTSe thin films were characterized by XRD, Raman, SEM and EDS, respectively. It was found that the crystallization quality of the thin film gradually improved with increasing temperature, and CZTSe thin films annealed at 530°Chad the best crystallization quality. The results showed that the surfaces were flat and dense without obvious secondary phase. Complete CZTSe thin films solar cells were prepared by common structure. The electrical properties of solar cells were tested by Hall, EQE and J-V. The results showed that the maximum mobility was 4.33 cm2V-1S−1, and the maximum power conversion efficiency was 3.65%, with an open circuit voltage of 346 mV, a short circuit current density of 31.36 mA/cm2 and a fill factor of 33.57%.

Influence of double current injection annealing on anti-LID effect in mono-like cast silicon PERC solar cells

Mono-like cast silicon (ML C-Si) passivated emitter and rear cell (PERC) solar cells with high performance and low price are becoming popular in the modern PV market. In this work, mono-like cast silicon PERC solar cells with B and Ga co-doping were treated by single current injection annealing (CIA) process and double CIA process. According to Light-induced degradation (LID) effect analysis, it was found that both single CIA process and double CIA process would enhance the electrical properties of the solar cells. After a light soaking treatment for 60 kWh, the efficiency of the solar cells treated by single CIA process decreased by 1.96% comparing with that before the CIA process. In contrast, the efficiency of the solar cells treated by double CIA process decreased by only 1.13%. All the results, including changes in other electrical properties of solar cells, showed that double CIA process would effectively enhance the anti-LID effect of ML C-Si PERC solar cells.

Comparative study of Cu2ZnSnSe4 solar cells growth on transparent conductive oxides and molybdenum substrates

Cu2ZnSnSe4 (CZTSe) thin films have been synthetized by cosputtering followed by a selenization treatment on Mo and transparent conductive oxide (TCO) coated soda lime glass substrates, such as ZnO:Al and SnO2:F (FTO). The aims of the present work is to investigate the impact of the TCO substrates on the CZTSe growth, the reactions at the back contact and the electrical properties of solar cells. The results show that the morphology of CZTSe is affected by the TCO back contacts. It is found that TCO acts as a diffusion barrier of Na from soda lime glass to CZTSe. Thus low incorporation of Na during the annealing could explain the difference in grain size of CZTSe deposited on TCO. Moreover it is evidenced chemical reactions between TCO and CZTSe which affects the interface. While the efficiency up to 8% is obtained for CZTSe based solar cells deposited on Mo substrate, the efficiency drops to 2.3% for the solar cells deposited on FTO. The low efficiency is explained by the recombination at the back contact due to the formation of the ZnO secondary phase at the CZTSe/FTO interface.

Determination of the electronic properties of Cu2ZnSnSe4-based solar cells by impedance spectroscopy and current–voltage characteristics analysis

Cu2ZnSnSe4 (CZTSe) thin films were synthesized by a cosputtering–annealing process and characterized as absorber layer of solar cells. Electrical characteristics of the solar cells were analyzed by coupling current–voltage measurements with impedance spectroscopy. The slightly p-type nature of the CZTSe absorber is evidenced with a doping level as low as 1.4 × 1015 cm−3. The solar cells exhibit a dominant recombination pathway in the space charge region in which it was revealed an apparent increase of the doping due to the ionization of deep level in the bandgap. Moreover, open circuit voltage of solar cells is found to be mainly limited by the low built-in voltage at the CdS/CZTSe interface. We conclude that the device architecture can play a major role in the electrical properties of solar cells.

Effects of screen printing and sintering processing of front side silver grid line on the electrical performances of multi-crystalline silicon solar cells

In this paper, the influence of screen-printing technology, sintering temperature, and the belt speed of sintering furnace on electrical properties of solar cells were researched. It is found that the morphology and aspect ratio of grid line are strongly influenced by printing parameters including the snap-off distance, the squeegee pressure and the squeegee speed. A number of comparative experiments showed that the electrical performance of solar cells was the best when the snap-off distance is 1200 µm, the squeegee pressure is 75 N, and the squeegee speed is 220 mm/s. Meanwhile, the surface morphology of the front electrode grid line prepared with the above optimum technology parameter is smooth and dense, and possesses good aspect ratio. To better understand the contact quality, the influence of sintering peak temperature on the electrical performance of solar cells was deeply studied. The results show that when the peak temperature was 900 °C, the series resistance (Rs) possesses the minimum value and the open circuit voltage (Voc), fill factor (FF), and conversion efficiency (Eff) all possess the maximum values. The effect of belt speed of sintering furnace on the electrical performance of the cells was also investigated. It is found that the electrical performance parameters were the optimal at the belt speed of 245 in/min.

Electrical and optical properties of Si microwire solar cells

A record-high efficiency of 16.92% was realized by using microscale-patterned Si solar cells. Si microwire (SiMW) solar cells were designed to compare their performances with the standard flat-Si solar cell. The diameter and period of SiMWs were tuned to investigate the effects on the operation and the electrical properties of the solar cells. The highest efficiency SiMW solar cell has a width of 1.57µm to provide the significantly enhanced efficiency of 16.92% from 10.15% of the flat-Si solar cell, due to the improved values of open circuit voltage (608mV), short circuit current density (36.47mA/cm2) and fill factor (76.29%). Impedance spectroscopy and capacitance-voltage studies were carried out to obtain series and shunt resistances, built-in potential, acceptor carrier density, depletion width and flat band potential. Optical properties of SiMW solar cells were analyzed by external and internal quantum efficiencies. The carrier lifetime was measured by using open circuit voltage decay technique. Systematic analyses were performed to reveal the optical and electrical features of SiMW solar cells. These findings may provide efficient design schemes for high-performing solar cells using structured platforms.

The Study of Optical and Electrical Properties of Solar Cells With Oblique Incidence

The optical and electrical properties of organic solar cells with metallic Ag incorporating into the PEDOT:PSS layer in the case of oblique incidence are numerically investigated based on in house finite-difference frequency-domain code. It is found that the light absorption decreases with the increase of incident angle, and the absorption enhancement varies slightly due to the contribution of the broadband surface plasmon (SP)-mode. Since the absorption reduces at large incident angle, the short-circuit current undoubtedly decreases, thus fill factor and power conversion efficiency reduce accordingly. However, there is little variety of open-circuit voltage, which indicates that open-circuit voltage is independent of incident angle. Our results can be used as a reference for better understanding of the optical and electrical properties of organic solar cells with oblique incidence.

Study on the thickness effect of wide-bandgap CuGaSe2 thin films for applications with tandem solar cells

For application on the top cell of a tandem structure, chalcopyrite CuGaSe2 (CGS) thin films were prepared on as-deposited 200-nm-thick indium-tin-oxide (ITO) thin films grown by using radiofrequency (RF) magnetron sputtering. CGS thin films with a wide bandgap of 1.63 eV for use in high open-circuit-voltage solar cells were deposited by using a three-stage co-evaporation process with Cu, Ga, and Se elemental sources with compositional ratios of Cu/Ga = 0.88 and Se/(Cu + Ga) = 0.98. In this study, we examined the effect of the thickness of the top-cell CGS thin films on the tandem cell performance, which is a key factor for improving the cell’s efficiency for optimum light absorption. The film thickness was varied from 0.5 μm to 2 μm in intervals of 0.5 μm by controlling the process time to confirm the optical and the electrical properties of solar cells. Based on our experimental results as a function of the CGS film’s thickness, we achieved a solar cell efficiency of 5.77% with a 1.5-μm-thick CGS thin film in the cell structure fabricated as Al/ZnO: Al/i-ZnO/CdS/CGS/ITO/SLG.

Application Of Artificial Neural Networks In Modeling Of Manufactured Front Metallization Contact Resistance For Silicon Solar Cells

Abstract This paper presents the application of artificial neural networks for prediction contact resistance of front metallization for silicon solar cells. The influence of the obtained front electrode features on electrical properties of solar cells was estimated. The front electrode of photovoltaic cells was deposited using screen printing (SP) method and next to manufactured by two methods: convectional (1. co-fired in an infrared belt furnace) and unconventional (2. Selective Laser Sintering). Resistance of front electrodes solar cells was investigated using Transmission Line Model (TLM). Artificial neural networks were obtained with the use of Statistica Neural Network by Statsoft. Created artificial neural networks makes possible the easy modelling of contact resistance of manufactured front metallization and allows the better selection of production parameters. The following technological recommendations for the screen printing connected with co-firing and selective laser sintering technology such as optimal paste composition, morphology of the silicon substrate, co-firing temperature and the power and scanning speed of the laser beam to manufacture the front electrode of silicon solar cells were experimentally selected in order to obtain uniformly melted structure well adhered to substrate, of a small front electrode substrate joint resistance value. The prediction possibility of contact resistance of manufactured front metallization is valuable for manufacturers and constructors. It allows preserving the customers’ quality requirements and bringing also measurable financial advantages.

The operation mechanism of poly(9,9-dioctylfluorenyl-2,7-diyl) dots in high efficiency polymer solar cells

The highly efficient polymer solar cells were realized by doping poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) dots into active layer. The dependence of doping amount on devices performance was investigated and a high efficiency of 7.15% was obtained at an optimal concentration, accounting for a 22.4% enhancement. The incorporation of PFO dots (Pdots) is conducted to the improvement of Jsc and fill factor mainly due to the enhancement of light absorption and charge transport property. Pdots blended in active layer provides an interface for charge transfer and enables the formation of percolation pathways for electron transport. The introduction of Pdots was proven an effective way to improve optical and electrical properties of solar cells.

A general design rule to manipulate photocarrier transport path in solar cells and its realization by the plasmonic-electrical effect.

It is well known that transport paths of photocarriers (electrons and holes) before collected by electrodes strongly affect bulk recombination and thus electrical properties of solar cells, including open-circuit voltage and fill factor. For boosting device performance, a general design rule, tailored to arbitrary electron to hole mobility ratio, is proposed to decide the transport paths of photocarriers. Due to a unique ability to localize and concentrate light, plasmonics is explored to manipulate photocarrier transport through spatially redistributing light absorption at the active layer of devices. Without changing the active materials, we conceive a plasmonic-electrical concept, which tunes electrical properties of solar cells via the plasmon-modified optical field distribution, to realize the design rule. Incorporating spectrally and spatially configurable metallic nanostructures, thin-film solar cells are theoretically modelled and experimentally fabricated to validate the design rule and verify the plasmonic-tunable electrical properties. The general design rule, together with the plasmonic-electrical effect, contributes to the evolution of emerging photovoltaics.

Characterisation of InAs/GaAs quantum dots intermediate band photovoltaic devices

The authors report on the structural, the optical and the electrical properties of solar cells containing 20 layers of doped InAs/GaAs quantum dots (QDs). The structures were grown by molecular beam epitaxy and contain n dopant sheet densities of 8 and 16 × 1010 cm−2, respectively, in between the QD layers. Under a 1 sun illumination, the open-circuit voltage (Voc) and the efficiency of the 8 × 1010 cm−2 n-doped sample were increased to values of 0.73 V and 9.7%, respectively, compared with a reference undoped sample (a Voc of 0.70 V and an efficiency of 9.0%). However, the short-circuit current density (Jsc) decreased from 20.1 to 17.4 mA/cm2 indicating bandfilling within the QD array.