Types Of Silicon Solar Cells Research Articles

A Horizontal Double‐Sided Copper Metallization Technology Designed for Solar Cell Mass‐Production

ABSTRACTIn the international photovoltaic market, the “carbon footprint” label has received great attention, and low‐carbon footprint products are widely popular. Compared with metallic silver, copper has the characteristics of low carbon emissions and low cost, which can effectively reduce the carbon footprint. Based on this, this article reports a horizontal double‐sided copper metallization technology. This technology can not only metalize the front and back sides of various types of silicon solar cells at the same time but also has fast speed, good uniformity, and simple process, making it suitable for the industrial mass production of solar cells. This article describes the structure and manufacturing process of TOPCon solar cells patterned with an ultrashort pulse laser and metalized using this novel horizontal double‐sided copper metallization technology. In this batch, average efficiency reached above 26%.

Carbon Nanotube Electrode‐Based Perovskite–Silicon Tandem Solar Cells

Carbon nanotube electrode–laminated perovskite solar cells in combination with n‐type tunnel oxide–passivated contact silicon solar cells demonstrate a high power conversion efficiency (PCE) of 24.42% when stacked in tandem. This is compared with conventional indium tin oxide/MoOx‐deposited perovskite solar cells which give an efficiency of 22.35% when stacked in the same four‐terminal tandem system. Despite higher transmittance of the carbon nanotube electrode than that of the indium tin oxide/MoOx in the infrared range, the carbon nanotube electrode‐laminated devices show lower transmittance in the same region due to the total internal reflection and scattering as evidenced by optical simulation. Yet, the exceptionally high PCE of the carbon nanotube electrode‐laminated semitransparent devices far exceeding than that of the indium tin oxide/MoOx‐deposited semitransparent top cell outweighs the effect of the optical transparency. Four types of silicon solar cells are compared as the bottom subcells, and the n‐type tunnel oxide‐passivated contact silicon solar cells are the best choice mainly due to their high absorption in the long‐wavelength region. The obtained 24.42% efficiency is one of the high PCEs among the reported four‐terminal perovskite–silicon solar cells, and this article is the first demonstration of the carbon nanotube electrode application in tandem solar cells.

Modeling and Experimental Verification of the Currents Diffusion and Recombination: Application to Mono and Polycrystalline Silicon

We present a systematic procedure to obtain the main parameters that characterize a solar cell under conditions under illumination such as: resistors series and shunt short-circuit current, fill factor, saturation current, saturation current diffusion and recombination, using the least square method. We have clearly demonstrated that the current approximation to use a single exponential term with a factor of n diode to describe the behavior of the p–n junction appropriate but unable to differentiate between the diffusion saturation currents and recombination even using too sophisticated multimeters, and measures are taken with care. To achieve this goal the experimental measurements of the characteristic I–V, we have used the two types of silicon solar cells: mono and polycrystalline, varying light concentration. The potential applications of both single and poly-crystals are governed by the electrical properties, such as the mobility and lifetime of the carriers, which are greatly influenced by the defects contained in the material. The results obtained show clearly that the structural defects of the grain boundaries associated with the segregated atoms promote the recombination of minority carriers. We employ also the intensity–voltage measurement to solar cells mono and polycrystalline under illumination to understand the recombination and diffusion currents behavior at the p–n junction.

Performance of silicon solar cells under filtered spectra and different light intensities

Solar cells operate under various light intensities. In addition, in a tandem solar cell configuration, the bottom cell receives a spectrum that is filtered by the top cell. The performance of the bottom cell at low light intensity is thus of great importance. In this paper, we study various types of silicon solar cells under various light intensities and filtered spectra. We find that, as expected, the short-circuit current varies linearly with the illumination intensity, regardless of the input spectrum. However, we also observe that for a constant number of incident photons but different long-pass filters (i.e., different photogeneration profiles), the short-circuit current density of the solar cells reduces with increasing cut-on wavelength of the used filter. According to our analysis, the loss in short-circuit current can be partly explained by the strong wavelength dependence of the external quantum efficiency at long wavelengths (1050–1200 nm) as well as the different carrier generation profiles under filtered spectra.

Study on light-induced degradation of silicon wafers and solar cells

In this paper, the laws of light-induced degradation (LID) in silicon wafers and solar cells are investigated by using xenon lamp as light source. There are tested 15 types of the silicon wafers contain the including primary wafer, chemical thinned wafer, thermal oxidation passivation wafer, passivation SiNx:H wafer deposited by plasma enhanced chemical vapor deposition, iodine passivation wafers of three different types of silicons: B-doped CZ-Silicon, B-doped Multicrystalline (MC) silicon, and B-doped Upgraded-Metallurgical-grade (UMG) silicon. There are tested 3 types of silicon solar cells: CZ solar cell, MC solar cell, and UMG solar cell. The light intensity is 1000 W/m2 in test. By using WT-2000 tester and solar cells I-V tester, the variations of minority carrier lifetimes of silicon wafers and the I-V characteristic parameters of solar cells with time of light exposure are tested and recorded. Finally the law of LID is found. Under our light condition (light source is a xenon lamp with a light intensity of 1000 W/m2), all kinds of silicon wafers and solar cells are degraded rapidly within the first 60 min, then slowly until the 180 min, finally the rate tends to 0. The LID becomes very slight after 180 min lighting.

Porous silicon in solar cell structures: a review of achievements and modern directions of further use

Porous silicon, which is being obtained by electrochemical etching of silicon wafers in electrolytes on the base of hydrofluoric acid, recently attracted the attention of specialists in photovoltaics even more due to a number of its unique properties. However, at present, acceptable results are obtained for the use of porous silicon as antireflecting coating for silicon solar cells only. In the present paper, previous experience of the use of por-Si in the silicon solar cells has been reviewed. On the base of examination of the porous silicon properties, a number of new directions of improvement of photoconversion efficiency of structures with optimized layers of porous silicon are proposed. The results of numerical calculations carried confirm perspectiveness of use of porous silicon for efficiency improvement for different types of silicon solar cells. These can be increased of their internal quantum efficiency, expansions of operating spectral range toward ultra-violet and infrared spectrum range, decrease of losses of photogenerated power due to the influence of bulk and surface recombination.

Modelling free-carrier absorption in solar cells

Free-carrier absorption can be a significant parasitic optical absorption process in solar cells. Although estimates of its influence have been made in the past, it has not previously been incorporated into a numerical semiconductor device simulator and studied in conjunction with other effects. A finite element model of free-carrier absorption is presented that incorporates the dependency of the absorption coefficient on the carrier concentration profile, including the change in carrier density that occurs across a single finite element. This model has been implemented in the semiconductor modelling program PC1D for Windows, and used to simulate the effects of free-carrier absorption on several types of silicon solar cells. It was found to have only a very small effect on cell efficiency, but can significantly affect the long-wavelength spectral response, which has implications for device characterization. Empirical equations for the behaviour of free-carrier absorption in a variety of materials are presented. © 1997 John Wiley & Sons, Ltd.

Low Energy Proton Damage to Solar Cells

Various types of silicon solar cells have been irradiated with 4.6 - 4.8 Mev protons in two separate experiments. In the first experiment, variations included the bulk material, impurity concentration, and oxygen concentration; the second experiment involved the cells of various manufacturers. Changes in diffusion length, spectral response, and efficiency under sun-like illumination are presented. Annealing effects in terms of the aforermentioned parameters are given. Comparison of the effects of this damage to that of 1 Mev electrons is made. Some preliminary results on the effects of proton damage to GaAs photovoltaic cells are also mentioned.