Optimization of micron size passivated contact and doping level for high efficiency interdigitated back contact solar cells

The Interdigitated back contact (IBC) solar cell is one of the most efficient commercial solar cells in the PV market. In order to improve the IBC solar cell efficiency, the entire solar cell structure must be well designed. The first issue is the solar cell’s doping level, including the p+ and n+ surfaces. The second is that the contact and passivation must be optimized. In this paper, we analyzed the recombination parameter (Jo) and specific contact resistivity (ρc) which are influenced by doping level, contact size and passivation. We found that the Jo decreases regularly as the ratio of contact size decreases in the diffusion wafer. An industrial, cost effective IBC solar cell fabrication with laser process was developed. The IBC solar cell with micron size contact and special doping level gave Voc of 690.0 mV, Jsc of 42.0 mA/cm2, FF of 81.0%, and η of 23.5%. The software 3D Quokka@ was used to calculate the IBC solar cell efficiency through simulation using a device model. Through the energy loss analysis, the simulation indicated that IBC solar cell with 25.0% efficiency could achieve with optimized doping level, micron size passivated contact, low contact resistance in the high bulk lifetime wafer.