27.6% Perovskite/c-Si Tandem Solar Cells Using Industrial Fabricated TOPCon Device

The tandem cell structure is the most promising solution for the next generation photovoltaic technology to overcome the single-junction Shockley–Queisser limit. The fabrication of a perovskite/c-Si monolithic tandem device has not yet been demonstrated on a c-Si bottom cell produced from an industrial production line. Here, a c-Si cell with a tunneling oxide passivating contact (TOPCon) structure produced on a production line as the bottom cell of a tandem device, and a top cell featuring solution-processed perovskite films to form the tandem device are used. The c-Si cell features a rough damage etched, but untextured front surface from the wafering processes. To combat the challenge of rough surfaces, several strategies to avoid shunt paths across carrier transport layers, absorber layers, and their interfaces are implemented. Moreover, the origin of reflection loss on this planar structure is investigated and the reflection loss is managed to below 4 mA cm⁻². In addition, the source of the voltage loss from the TOPCon bottom cell is identified and the device structure is redesigned to be suitable for tandem applications while still using mass production feasible fabrication methods. Overall, 27.6% efficiency is achieved for a monolithic perovskite/c-Si tandem device, with significant potential for future improvements.