This paper describes the application of an inkjet chemical lithography patterning method for back contact solar cell metallisation where the novolac polymer resist is retained in the final device to act as a rear insulation layer. Point openings in the polymer layer with a diameter as small as 20-25μm were achieved and used to etch holes in an underlying silicon nitride (SiN x ) layer. The polymer was retained on the device after etching the SiN x and an area-normalised resistance of 10 11 Ω cm 2 was measured after heating at 130°C for 10 min. The insulating properties of the polymer were not significantly altered after an additional thermal step in which an aluminium layer was deposited over the resist and sintered at 150 °C for 10 min to simulate the cell lamination process. Optical simulations demonstrated that, although the heat-treated polymer can absorb some light, a photocurrent gain up to 0.5mA/cm 2 can be expected for cells with a rear polymer layer of thickness 4μm compared to cells without the polymer assuming the same metal rear reflector coverage and cell thickness.
Li, Z., Li, Y., Ouyang, Z., Hsiao, P. C., Jiang, Y., & Lennon, A. (2015). Electrical and optical analysis of polymer rear insulation layers for back contact cells. In Energy Procedia (Vol. 77, pp. 744–751). Elsevier Ltd. https://doi.org/10.1016/j.egypro.2015.07.105