The Study Of The Rear Surface Passivation For Silicon Solar Cells

Drastic cost reduction of bulk crystalline silicon soalr cells for the competitiveness of the drastic cost reduction of bulk crystalline silicon soalr cells for the competitiveness of the photovoltaic industry requires the use of the thinner substrates. requires. The rear passivation is more and more important for the thinner wafers that is the trend of photovoltaic industry. The rear passivation technologies are systematically investigated by analyzing the minor carriers effective lifetime and the local back contact formed by the screen printing.First, we use the PC1D to simulate depanency of the solar cells conversion efficiency on the backside sureface. The CTO RTO SIN and stacks as the rear passivation medium films. It was found throuth QSSPCD that the sin film were less than 17nm and exceeded 26nm, the rear surface passivation effect reduced and kept accord, respectively. There is a little effect on the rear passivation with the sin refractive index from 1.9-2.3. The anneal characteristic of the refractive index 2.3 as 2.0, the both side sin passivation has the same effect on the different acid surface.just to the stacks, after the RTP, the lifetime of diffused wafers decreas a few. When the CTO oxygenation time is about at 80 minutes, the lifetime decreses gradually. While when at 50-80minutes, the lifetime increase.Second, it is found that the result of removing back junction with three different methods has the same effect. We use the screen printing technology to make the gride back contact with the area of the rear surface 25% and point contact with diameter of 250um and space 2mm, but there is the same problem in the two different forms. The series of the resistance is too big, the shunt resistance is too small. While we use the acid method, the electric performance parameter become a little better.