Design, realization and loss analysis of efficient low-cost large-area bifacial interdigitated-back-contact solar cells with front floating emitter

Abstract

Large-area (251.96 cm 2 ) bifacial interdigitated-back-contact (IBC) solar cells are presented in this work. We employ front floating emitter (FFE) to replace the front surface field (FSF) to simplify the process sequences. A simplified process flow is exploited to fabricate the IBC solar cells through industrial equipment and compatible processes. Double side boron diffusion followed by etch-back to form the emitter and lightly doped front surface, reducing high-temperature influence on the bulk lifetime and fabrication complexity. Ion implantation and anneal process is applied for base doping. The cell conversion efficiency reaches 22.92%, independently certificated by Fraunhofer Institute for Solar Energy System CalLab (Fraunhofer ISE). The IBC solar cells feature an open metallization grid, which offers a bifacial response with the bifaciality reaches to 72%. Only one-step mask and opening procedure was used, which greatly simplified the process. These results demonstrate the feasibility of this simplified process for manufacturing low-cost high-efficiency of IBC cells. Key parameters such as surface recombination J 0 , metal contact recombination J 0-metal , contact resistivity of the cells are extracted by specially designed structures. Loss analysis shows that further efficiency improvement can be attained though reducing the contact resistance and metal contact recombination. The results in this work indicates the potential of this novel process for producing low-cost high-efficient IBC solar cells. Large-area efficient IBC solar cells are fabricated by using front floating emitter (FFE), which reducing the process complex and save cost. With the simplified process, the conversion efficiency of 22.92% and bifaciality of 72% are attained. Through special structures and patterns designing, the performance parameters ( J 0 , J 0-metal , and ρ c ) are investigated, and the losses of the IBC cell are analyzed by numerical simulation. • Large-area bifacial interdigitated back contact (IBC) solar cell are fabricated through industrial equipment. • Front floating emitter (FFE) replace of FSF reduce electrical shading effect increase the process tolerance. • Front side etch back to from FFE, ion-implantation to from BSF simplified the process of IBC cell. • Extract key parameters ( J 0 , J 0-metal , ρ c ), Quokka 3D simulator was performed to estimate the performance of solar cell. • The front efficiency is 22.92% and 16.54% on the back, the bifaciality is 72%.