A comprehensive investigation of the potential of metal assisted chemical etched (MACE) nano-textures over conventional micron-sized iso-textures for industrial silicon solar cell applications

• Published in: Solar energy Vol. 230; pp. 874 - 882
• Main Authors: Sreejith, K.P., Sharma, Ashok Kumar, Basu, Prabir Kanti, Kottantharayil, Anil
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01-12-2021; Pergamon Press Inc
• Subjects: Acid texturing; Chemical etching; Circuits; Comparative analysis; Contact resistance; Crystal structure; Crystallinity; Crystallites; Crystals; Diamond wire sawn wafers; Etching; High efficiency industrial silicon solar cells; Metal assisted chemical etching; Multi-crystalline silicon cells; Open circuit voltage; Photovoltaic cells; Scanning electron microscopy; Short circuit currents; Short-circuit current; Silicon; Silver; Solar cells; Solar energy; Diamond wire sawn wafers; Metal assisted chemical etching; High efficiency industrial silicon solar cells; Acid texturing; Multi-crystalline silicon cells
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2021.10.035

We present a comprehensive comparative analysis of acid textured and MACE (Metal Assisted Chemical Etching) nano-textured multi crystalline silicon (mc-Si) solar cells processed in an industrial cell line in terms of performance parameters. The batch average open circuit voltage of nano-textured solar cells was marginally lower and the measures for improving the same are discussed. Batch average short circuit current (JSC) and fill factor (FF) were respectively 0.65 mA-cm−2 and 0.7% (absolute) higher for MACE nano-textured solar cells. Significantly lower surface reflectance in MACE nano-textured cells in the blue and near infrared regions are found to be the reason for the enhancement in JSC. The main component of FF gain is identified as the lower series resistance in MACE cells. The contact formation mechanism in screen printed mc-Si solar cells, investigated using scanning electron microscopy, revealed that the elevated portions at the boundaries of the textures act as favorable sites for silver crystallite precipitation. A larger areal density of such sites is observed on the MACE nano-textured surface than in case of acid textured solar cells, leading to a much lower series resistance. The results suggest the potential for the application of MACE in the more popular mono-crystalline silicon cell technology for further reduction of contact resistance. Alternatively, MACE may be used to obtain similar contact resistance with lower amount of silver paste, compared to iso- and pyramid textured solar cells.
•MACE nano-textures offer lower reflection and higher fill factor than iso-textures.•Gain in fill factor in nano-textured cells is due to lower series resistance.•Elevated portions of textures are the favorable Ag crystallite precipitation sites.•Large area density of MACE nano-textures lower the series resistance significantly.