A Novel Method to Achieve Selective Emitter Using Surface Morphology for PERC Silicon Solar Cells

• Published in: Energies (Basel) Vol. 13; no. 19; p. 5207
• Main Authors: Ju, Minkyu, Park, Jeongeun, Cho, Young Hyun, Kim, Youngkuk, Lim, Donggun, Cho, Eun-Chel, Yi, Junsin
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-10-2020
• Subjects: Caustic soda; Cytology; Doping; doping process; Efficiency; Electrical resistivity; Emitters; Etching; Fabrication; Morphology; PERC; Phosphorus; Photovoltaic cells; selective emitter; Silicon nitride; Sodium; solar cell; Solar cells; surface morphology; Wafers
• ISSN: 1996-1073; 1996-1073
• DOI: 10.3390/en13195207

Recently, selective emitter (SE) technology has attracted renewed attention in the Si solar cell industry to achieve an improved conversion efficiency of passivated-emitter rear-contact (PERC) cells. In this study, we presented a novel technique for the SE formation by controlling the surface morphology of Si wafers. SEs were formed simultaneously, that is, in a single step for the doping process on different surface morphologies, nano/micro-surfaces, which were formed during the texturing processes; in the same doping process, the nano- and micro-structured areas showed different sheet resistances. In addition, the difference in sheet resistance between the heavily doped and shallow emitters could be controlled from almost 0 to 60 Ω/sq by changing the doping process conditions, pre-deposition and driving time, and temperature. Regarding cell fabrication, wafers simultaneously doped in the same tube were used. The sheet resistance of the homogeneously doped-on standard micro-pyramid surface was approximately 82 Ω/sq, and those of the selectively formed nano/micro-surfaces doped on were on 62 and 82 Ω/sq, respectively. As a result, regarding doped-on selectively formed nano/micro-surfaces, SE cells showed a JSC increase (0.44 mA/cm2) and a fill factor (FF) increase (0.6%) with respect to the homogeneously doped cells on the micro-pyramid surface, resulting in about 0.27% enhanced conversion efficiency.