Purpose: – This paper aims to present the possibility of the technology of chemical metallization for the production of contact of photovoltaic cells. The developed technology allows you to perform low-cost contacts in any form. Design/methodology/approach: – The study used a multi- and monocrystalline silicon plates. On the surface of the plates, the contact by the electroless metallization was made. After metallization stage, annealing process in a temperature range of 100-700°C was conducted to obtain ohmic contact in a semiconductor material. Subsequently, the electrical parameters of obtained structures were measured. Therefore, trial soldering was made, which demonstrated that the layer is fully soldered. Findings: – Optimal parameters of the metallization bath was specified. The equations RS = f (metallization time), RS = f (temperature of annealing) and C-V characteristics were determined. As a result of conducted research, it has been stated that the most appropriate way leading to the production of soldered metal layers with good adhesion to the portion of selectively activated silicon plate is technology presented below in the following steps: masking, selective activation and nickel-plating of activated plate. Such obtained metal layers have great variety in application and, in particular, can be used for the preparation of electric terminals in silicon solar cell. Originality/value: – The paper presents a new, unpublished method of manufacturing contacts in the structure of the photovoltaic cell.

Purpose: The purpose of this study is comparison of the diffusion processes performed using the commercial available dopant paste made by Filmtronics and the original prepared liquid dopant solution. To decrease prices of industrially produced silicon-based solar cells, the new low-cost production processes are necessary. The main components of most popular silicon solar cells are with diffused emitter layer, passivation, anti-reflective layers and metal electrodes. This type of cells is prepared usually using phosphorus oxychloride diffusion source and metal pastes for screen printing. The diffusion process in diffusion furnace with quartz tube is slow, complicated and requires expensive equipment. The alternative for this technology is very fast in-line processing using the belt furnaces as an equipment. This approach requires different dopant sources. Design/methodology/approach: In this work, the diffusion processes were made for two different types of dopant sources. The first one was the commercial available dopant paste from Filmtronics and the second one was the original prepared liquid dopant solution. The investigation was focused on dopant sources fabrication and diffusion processes. The doping solution was made in two stages. In the first stage, a base solution (without dopants) was made: dropwise deionized (DI) water and ethyl alcohol were added to a solution consisting of tetraethoxysilane (TEOS) and 99.8 per cent ethyl alcohol. Next, to the base solution, orthophosphoric acid dissolved in ethyl alcohol was added. Findings: Diffused emitter layers with sheet resistance around 60 Ω/sq were produced on solar grade monocrystalline silicon wafers using two types of dopant sources. Originality/value: In this work, the diffusion processes were made for two different types of dopant sources. The first one was the commercial available dopant paste from Filmtronics and the second one was the original prepared liquid dopant solution.

Purpose: The main aim of this study was a preparation development of dopant solution (DS) which can be deposited by a spray-on method and subsequently allows obtaining the n+ emitter layer with surface resistance in the range of 65-80 Ω⁻¹. The intention of chosen spray-on method was to gain a cheaper way of dopant source deposition, compared to the commonly used methods, which is of particular importance for the new low-cost production processes. Design/methodology/approach: This paper presents the sequence in producing a spray-on glass solution (DS) with very high concentration of phosphorus, which allows to perform diffusion doping at relatively low temperatures. DS contained deionized water, ethyl alcohol, tetraethoxysilane and othophosphoric acid. Findings: The sequence in producing a DS was performed with respect to enabling the application to silicon wafers by spray-on method. Furthermore, the equations defined density and viscosity of DS in term of storage time were referred to determine the possibility of applying this solution by spray-on method. Besides, the dependence of the emitter surface resistance on the doping (diffusion) time was determined. Accordingly, optimal process conditions were specified. Originality/value: The paper presents a new, so far unpublished composition of DS with very high concentration of phosphorus, which can be applied using a spray-on method. Moreover, original are also investigations respecting some properties of obtained DS relative to storage time.

Purpose: – This paper aims to present the results of measurements of the photovoltaic structures made by electroless selective metallization technology. The developed technology provides low-cost contacts in any form, and parameters of photovoltaic cells made in this technology provide reliable results, comparable with those usually used. Design/methodology/approach: – In this paper, photovoltaic cells with contacts based on Nip and NiCuP alloy were performed. As a substrate, mono- and multicristaline silicon was used. After photovoltaic cells have been prepared, sheet resistance of the contact layers and electrical parameters were measured. Composition and structure of contact layers were also measured. Findings: – Obtained results of sheet resistance and contact layers are repeatable and comparable with previously published results. Electrical parameters of the photovoltaic cells made are comparable with used substrate and technologies. The authors have also noticed that the costs of the electroless metallization which is used to make contact layers is lower than metallization made by thick film or vacuum deposition technologies. Originality/value: – The paper presents new, unpublished results of electrical parameters of photovoltaic cells with contact layers made by electroless metallization. The original idea is the usage of metallization in an acidic solution (pH = 2). In this proposed technology, photovoltaic cells on mono- and multicrystalline silicon plates were performed.

Purpose: The purpose of this paper is to present the possibility of technology of chemical metallization for the production of electrodes and resistors based on Ni–P alloy on silicon (Si), alundum (Al₂O₃) and low temperature cofired ceramic (LTCC) substrates. The developed technology provides low cost in any form. Design/methodology/approach: During the study monocrystalline Si plates and Al₂O₃ and LTCC substrates were used. On the surface of the substrates, the electrodes (resistors) by the electroless metallization were made. Subsequently, the electrical parameters of obtained structures were measured. Afterwards, trial soldering was made to demonstrate that the layer is fully soldered. Findings: Optimal parameters of the metallization bath were specified. As a result of the research conducted, it has been stated that the most appropriate way leading to the production of soldered metal layers with good adhesion to the portion of selectively activated Si plate and Al₂O₃ and LTCC substrates comprises the following technology: masking, selective activation, nickel-plating of activated plate. Such obtained metal layers have a great variety of application; in particular they can be used for the preparation of electric contacts in Si solar cells, production of electrodes and resistors and production of electrodes in thermoelectric structures. Originality/value: The paper presents a new, unpublished method of manufacturing electrodes (resistors) on Si plate and Al₂O₃ and LTCC substrates.

Purpose: The purpose of this paper is to develop a method of preparing spray-on dopant solutions that enable obtaining a p+ region forming a back-surface field (BSF) during the diffusion doping process. The spray-on method used allows to decrease the costs of dopant solution application, which is particularly significant for new low-cost production processes. Design/methodology/approach: This paper presents steps of production of high concentration boron dopant solutions enabling diffusion doping of crystalline p-type silicon surfaces. To check the fabricated dopant solutions for stability and suitability for spray-on application, their viscosity and density were measured in week-long intervals. The dopant solutions described in this paper were used in a series of diffusion doping processes to confirm their suitability for BSF production. Findings: A method of preparing dopant solutions with parameters enabling depositing them on silicon wafers by the spray-on method has been established. Due to hygroscopic properties of the researched dopant solutions, a maximum surrounding atmosphere humidity has been established. The solutions should not be applied by the spray-on method, if this humidity value is exceeded. The conducted derivatographic examination enabled establishing optimal drying conditions. Originality/value: The paper presents a new composition of a dopant solution which contains high concentration of boron and may be applied by the spray-on method. Derivatographic examination results, as well as equations describing the relation between dopant solution density and viscosity and storage time are also original for this research. The established dependencies between the sheet resistance of the fabricated BSF and the diffusion doping time are other new elements described in the paper.