Development and characterization of laser chemical processes for high efficiency silicon solar cells

The transfer of new concepts for high efficiency crystalline silicon solar cells to mass production requires industrially feasible technologies to fabricate local doping and metallization structures. The application of laser processing in combination with a liquid jet known as Laser Chemical Processing (LCP) offers the possibility to microstructure thin passivation layers and simultaneously create local doping structures within the ablated areas. The presented work demonstrates different application areas of LCP fabricated local boron and phosphorous doping structures for silicon solar cell applications and analyzes their impact on the electrical performance of the solar cell. The first application area for LCP is the fabrication of boron local back surface fields for p-type passivated emitter and rear locally diffused (PERL) silicon solar cells. The presented experimental results demonstrate for the first time the applicability of laser based boron LBSF structures in high efficiency silicon solar cells with solar cell conversion efficiencies of up to 20.9%. The second focus of this work is the fabrication of phosphorus selective emitter structures in combination with Ni-Cu/Ag plated metal contacts. The main aspects in this context are the identification of theoretical improvements and limitations of a selective emitter design, the fabrication of large area (156x156 mm²) silicon solar cells with and without selective emitter design in combination with a detailed loss analysis and Ni-Cu/Ag plated metal contacts and the analysis of annealing induced non-linear shunts in Ni plated solar cells.