The world's ever increasing demand for energy necessitates technologies that generate electricity from inexhaustible and easily accessible energy sources. Silicon photovoltaics is a technology that can harvest the energy of sunlight. Its great characteristics have fueled research and development activities in this exciting field for many years now. One of the most important activities in the solar cell community is the investigation of alternative fabrication and structuring technologies, ideally serving both of the two main goals: device optimization and reduction of fabrication costs. Inkjet technology is practically evaluated along the whole process chain. Research activities cover many processes, such as surface texturing, emitter formation, or metallization. Furthermore, the inkjet technology itself is manifold as well. It can be used to apply inks that serve as a functional structure, present in the final device, as mask for subsequent structuring steps, or even serve as a reactant source to activate chemical etch reactions. This article reviews investigations of inkjet-printing in the field of silicon photovoltaics. The focus is on the different inkjet processes for individual fabrication steps of a solar cell. A technological overview and suggestions about where future work will be focused on are also provided. The great variety of the investigated processes highlights the ability of the inkjet technology to find its way into many other areas of functional printing and printed electronics.

In this paper, first generation back-contact backjunction (BC-BJ) silicon solar cells with cell efficiencies well above η = 20% were fabricated. The process sequence is industrially feasible, requires only one high-temperature step (codiffusion), and relies only on industrially available pattering technologies. The silicon-doping is performed from pre-patterned solid diffusion sources, which allow for the precise adjustment of phosphorus-and boron-doping levels. Based on the investigated process technologies, BC-BJ solar cells with gap and without gap between adjacent n + -and p + -doped areas were processed. On the one hand, a strong reduction of the process effort is possible by omitting the gap regions. On the other hand, parasitic tunneling currents through the narrow space charge region may occur. Hence, deep doped areas were realized to avoid tunneling currents in gap-free BC-BJ cells. This paper finishes with a detailed characterization of the manufactured cells including important cell measurements like I-V, SunsVOC, quantum efficiency, and an analysis of the cell specific fill factor losses.

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Two approaches for structuring thin metal layers for seed and growth metallization for back-contacted solar cells using hot-melt inkjet as masking technology are evaluated. The characteristics of a hot-melt printed image relevant for process development are discussed. A metal lift-off process and a metal etching process, both creating a meander-shaped opening in a metal layer - hence an interdigitated grid - based on hot-melt inkjet are established. The process sequences are characterized regarding the shunt resistance between the grids and the contact resistance to an underlying emitter layer on appropriate test structures. The contact resistance is found to be increased on samples fabricated by metal lift-off compared to samples fabricated by metal etching. The lift-off process is found to open lines with a width of around 120 m reliably, whereas a line opening width in the range of 50 m is reliably represented with the etching process sequence, whereas a high shunt r esistance is considered the criterion for a successful process