Enhancing Metal Grid Adhesion on Silicon Heterojunction Solar Cell by Annealing and Acid Etching the Indium Tin Oxide Layers

In order to enhance the metal grid adhesion on silicon heterojunction (SHJ) solar cell, an acid etching treatment is applied onto the indium tin oxide (ITO) layers before preparing the Ag grid by screen printing. At the same time, different annealing procedures to the ITO layers prior to the acid etching are comparatively investigated according to the variation of the ITO and SHJ solar cell performance. It is found that the acid etching can improve the adhesion of Ag grid on the ITO surface by modifying the ITO surface roughness. However, the acid corrosion can degrade the electrical and optical properties of ITO layers. To mitigate this, an annealing process is implemented prior to the acid corrosion. The annealing treatment can enhance the ITO resistance against the acid etching via promoting the ITO crystallization and thus reduce the etching depth of ITO layers. The ITO crystallization can also improve the conversion efficiency of the SHJ solar cells. So, the appropriate combination of annealing and acid etching is an effective way to achieve high‐efficiency SHJ solar cells with strong metal grid adhesion, which will be very beneficial for improving the stability of the SHJ solar cells in the field application.