Decoupling the metal layer of back contact solar cells – optical and electrical benefits

Abstract We report on our work on optimising the optical and electrical properties of back contact solar cells. We use a spin coated Novolac polymer layer between metal layer and solar cell. This helps to decouple the metal optically from the solar cell and also enables the application of symmetrical metal finger widths on solar cells with thin BSF regions and large emitter regions. While the application of the polymer layer adds process steps to the cell flow it simplifies the metal contact separation, as the metal can be laser ablated from the polymer without damaging the solar cell. Further, the polymer can be inkjet patterned and used as an etch mask for a wet chemical contact opening of the underlying dielectric passivation layer.