Conductive Hole-Selective Passivating Contacts for Crystalline Silicon Solar Cells

Defect state passivation and conductivity of materials are always in opposition; thus, it is unlikely for one material to possess both excellent carrier transport and defect state passivation simultaneously. As a result, the use of partial passivation and local contact strategies are required for silicon solar cells, which leads to fabrication processes with technical complexities. Thus, one material that possesses both a good passivation and conductivity is highly desirable in silicon photovoltaic (PV) cells. In this work, a passivation-conductivity phase-like diagram is presented and a conductive-passivating-carrier-selective contact is achieved using PEDOT:Nafion composite thin films. A power conversion efficiency of 18.8% is reported for an industrial multicrystalline silicon solar cell with a back PEDOT:Nafion contact, demonstrating a solution-processed organic passivating contact concept. This concept has the potential advantages of omitting the use of conventional dielectric passivation materials deposited by costly high-vacuum equipment, energy-intensive high-temperature processes, and complex laser opening steps. This work also contributes an effective back-surface field scheme and a new hole-selective contact for p-type and n-type silicon solar cells, respectively, both for research purposes and as a low-cost surface engineering strategy for future Si-based PV technologies.