Potential structure of c-Si bottom sub-cell in bifacial four-terminal III-V//c-Si multijunction devices

• Published in: Solar energy 2023-06, Vol.257, p.10-17
• Main Authors: Phong Pham, Duy, Han, Seungyong, Phuong Nguyen, Minh, Shin, Hyun-Beom, Kwan Kang, Ho, Kim, Youngkuk, Yi, Junsin
• Format: Article
• Language: English
• Subjects: Bifacial illumination; III-V//c-Si multijunction solar cells; TOPCon solar cells; Wide-gap materials
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2023.04.015

[Display omitted] •4-terminal III-V//c-Si multijunction device with a TOPCon bottom cell.•Wide-gap poly-SiOx as back surface field for TOPCon device.•Bifacial illumination of the 4-terminal device is examined.•Over 34% of cell efficiency with extra 0.25-sun illumination at the back. We propose a structural innovation for a four-terminal III-V//crystalline silicon (c-Si) multijunction (MJ) device under bifacial illumination. The top cell is a double-junction gallium indium phosphide (GaInP)/gallium arsenide (GaAs) cell structure, and the bottom cell is a tunnel oxide passivating contact (TOPCon) structure with a boron-diffusion emitter and a wide-gap polysilicon oxide (poly-SiOx) passivating rear contact. To maximise the albedo-reflectance light transmitted into the c-Si absorber, the wide-gap poly-SiOx passivating contact is intended to replace the conventional narrow-gap polysilicon (poly-Si) passivating contact at the rear of the TOPCon. With an extra 0.25-sun illuminated light at the back, the bottom cell's conversion performance improves by 14.5%. When compared to mono-illumination, bifacial illumination increases the overall efficiency of the MJ device by 2.67%. The design shows great potential for enhancing further the conversion performance of the bifacial GaInP/GaAs//TOPCon MJ devices using the wide-gap poly-SiOx passivating rear contacts.