Electrochemical nanofabrication for more sustainable photovoltaics

The installed photovoltaic (PV) capacity is expected to exponentially increase in the coming decade, presenting challenges like material scarcity and scalability. One of the critical materials used in PV applications is indium tin oxide (ITO), commonly used as the transparent conducting material. This thesis aims to replace ITO with silver nanowire (Ag NW) networks, fabricated through a combination of electrodeposition with nanoimprint lithography. This method offers a more sustainable, scalable production with precise control over size, shape, and alignment. We discuss the electrochemical theory and study the Ag nucleation on ITO substrates. Utilizing the double pulse method and substrate conformal imprint lithography, we have fabricated Ag NW grids on ITO. We find that the nucleation density of the silver nanoparticles is the key parameter for the successful homogeneous void-free filling of the template. These grids exhibit high optical transmission and low sheet resistance, yielding superior performance. The bottom-up approach allows for high aspect ratio nanowires, reducing sheet resistance without compromising transparency or carrier collection. Importantly, this technique can be directly applied to Si-based solar cells, as demonstrated with TOPCon cells, showing excellent transparency even at high angles of incidence. To further enhance the electrical performance of the grids, we use assembled Ag nanocubes as seeds for the electrochemical growth. Overall, this thesis contributes to a more sustainable solar energy infrastructure, opening new paths towards a cleaner, and more renewable energy future.