Laser-Induced BSF: A New Approach to Simplify IBC-SHJ Solar Cell Fabrication

Silicon heterojunction (SHJ) interdigitated back-contacted (IBC) solar cells currently hold the world record for conversion efficiency of silicon based, single junction solar cells. In order to use this technology for industrial applications, cost-effective strategies for amorphous silicon (a-Si: H) patterning of the back surface field (BSF) and emitter have to be developed. We propose a process flow that eliminates the need to align a-Si: H deposition steps. This is accomplished by the use of a low power, ultraviolet laser to transform an i-n-i-p a-Si: H layer stack into a fully working BSF. This process is referred to here as compensation lasering. In this manuscript, we first show a proof of concept of the compensation laser process using front and rear contacted SHJ solar cells. We then use Raman and SIMS characterization to show that the laser affects boron concentration to form a working BSF. Finally, we present precursors of a SHJ-IBC. Implied V-OC values of 732 mV have been achieved showing the potential of this technique as an SHJ-IBC process.