So far, monocrystalline silicon solar panels have developed rapidly in both research and industrialization.

    Among the many factors that affect C-Si cells, the improvement of the quality of silicon wafers makes the bulk recombination smaller and smaller, and the development of new passivation layers and their preparation technology greatly reduces the surface recombination. Among them, the recombination of the metal electrode and the C-Si contact becomes the key factor affecting the cell efficiency and is considered to be the last limiting factor close to the theoretical limit efficiency. In order to reduce the recombination at the contact point between metal and C-Si, on the one hand, the direct contact area between metal and C-Si is reduced by partially opening holes on the back of the cell (including PERC, PERL, and PERT, etc.). Although the conversion efficiency is at or close to 25%, there is still direct contact between metal and C-Si in these cells, the backside opening process is complicated, and it will cause damage to the silicon material at the opening.

    In addition, the local opening technique makes the carriers not only deviate from the migration path perpendicular to the contact surface but also may be crowded at the opening, which leads to the loss of fill factor. On the other hand, novel contact schemes need to be developed that can achieve both excellent surface passivation and separation and transport of carriers without the need for openings, i.e., carrier-selective passivation contacts. This solution can realize the passivation of the entire surface of the silicon wafer (including the contact area and the non-contact area), and at this time, the carriers are one-dimensional transport between the electrodes at both ends, which is beneficial to obtain a higher fill factor, and then improve its conversion efficiency.