Seed-Assisted Growth of Cast-Mono Silicon for Photovoltaic Application: Challenges and Strategies

Silicon has dominated the photovoltaic material market for a few decades. In contrast to perfectly crystallized Czochralski (CZ) silicon, casting multi-crystalline silicon attracts much more attention due to its low cost and high throughput, which meets the increasing demands of the rapidly developing photovoltaic industry. However, the unavoidable appearance of crystallographic defects seriously limits the performance improvement of solar cells. In this Review, a general overview of the recent efforts in high-quality casting silicon crystal techniques is provided, including the dendritic cast method, high-performance multi-crystalline silicon, and cast-mono silicon. Then, special attention is focused on the seed-assisted growth of cast-mono silicon, which shares some of the most favorable features of high solar cell efficiency offered by well-established CZ silicon and cost-effectiveness of cast multi-crystalline silicon. Nevertheless, this innovative growth technique facing a few challenges once impeded its mass scale production. The main issues concerning nucleation and growth control, extended defects as well as impurity contamination are addressed, which pave the way for this high-potential technology in applications for high-efficiency and low-cost solar cells.