(a) Schematic diagram of structure and (b) certified efficiency diagram of “indium-less and silver-free” SHJ solar cells

The research group led by Professor Xiaodan Zhang and Professor Ying Zhao of the College of Electronic Information and Optical Engineering of Nankai University, in collaboration with Suzhou Maxwell Technology Co., Ltd. and SunDrive Solar Pty. Ltd. which is an Australian metallization technology company, prepared cheap and mass-producible undoped tin oxide (SnO_x) electrode materials by sputtering at room temperature for the first time, which can replace the indium-based transparent electrodes in solar cells. Furthermore, the SnO_x film has good chemical stability. By superimposing SnO_x with IMO:H (hydrogenated transition metal doped indium oxide) into a bilayer film with a thickness ratio of 1:1, the electrical properties of films are improved and the contact resistance between bilayer film and carrier transport layer is reduced, thereby improving the performance of solar cells. In order to reduce the consumption of “silver”, another precious metal used in SHJ solar cells, copper electroplating is used in metallization process of solar cells. It improves the efficiency by increasing the electrode aspect ratio while saving the cost of expensive silver paste. Finally, an ISFH certified efficiency of 25.94% (total cell area of 274.4 cm²) was obtained in the form of indium-less transparent electrodes with electroplated copper electrodes. It is the highest efficiency among the published research on “indium-less” SHJ solar cells.

The research findings entitled “Silicon solar cell with undoped tin oxide transparent electrode” were published in Nature Energy, a top international academic journal in the field of energy. Qiaojiao Zou, a PhD student at Nankai University, is a co-first author, and Professor Xiaodan Zhang is a co-corresponding author.

This study proves the feasibility of undoped SnO_x transparent electrode materials combined with copper electrodes as an alternative to indium-based transparent electrode materials and silver electrodes. It provides a practical solution to solve the problems of costly silver paste and limited supply of indium metal. At the same time, it offers new ideas for the subsequent development of efficient “indium-free and silver-free” SHJ solar cells, helps to “reduce costs and increase efficiency” for SHJ solar cells, and provides key technological support for realizing the “dual carbon” goals.

Link:https://www.nature.com/articles/s41560-023-01331-7

（Edited and translated by Nankai News Team.)