SiPoly – Evaluating the potential of crystalline silicon solar cells with carrier-selective polymer layers

The aim of this joint project is to develop and evaluate a new process technology for photovoltaics, which will improve solar cell efficiency without increasing processing costs. The basic idea is to replace the hole collecting p+ layer of the silicon solar cell with a hole conducting polymer layer of PEDOT:PSS using a simple deposition technique. This polymer layer not only needs to form a good contact with silicon but also has to provide excellent passivation at the silicon/polymer interface. The approach of the SiPoly project is to replace the rear side passivation of silicon solar cells with two very cost-efficient, simple process steps: (i) deposition of the hole conducting polymer from the liquid phase under atmosphere and (ii) the full-area deposition of a low-cost metal foil or alternatively a low-temperature screen-printing metal paste that would be developed within the project. These adjustments have no impact on the front side of the solar cell, which can thus be processed using standard industry processes. This makes the new approach very attractive, as it can be easily implemented into existing production lines. The overall goal of the project is to evaluate possibilities of simplified processing of industrial-type solar cells through the implementation of conductive polymers capable of passivating the silicon surface in order to assess the feasibility of industrial application.