Source: World Scientific Publishing

The Impact of Surface Recombination on Solar Cell Efficiency

Understanding Surface Recombination

Surface recombination, which occurs at the surface of solar cells where the crystal lattice is disrupted, is a significant factor impacting solar cell efficiency. This process leads to high rates of recombination, which can limit the overall performance of the solar cell.

Causes of Surface Recombination

Defects and impurities present within or at the surface of the semiconductor contribute to surface recombination. The disruption of the crystal lattice at the surface of the solar cell creates a high recombination environment. Dangling bonds, or unpaired electrons, at the semiconductor surface are key contributors to the local recombination rate.

Surface Recombination Velocity

The surface recombination velocity, measured in cm/sec, is a parameter used to quantify the recombination at a surface. A surface with no recombination has a velocity of zero, while a surface with fast recombination limits the movement of carriers towards the surface. For most semiconductors, the surface recombination velocity is around 1 x 10^7 cm/sec.

Surface Passivation

To reduce surface recombination, a process known as surface passivation is employed. This technique involves growing a layer on top of the semiconductor surface to bind some of the dangling bonds, thereby decreasing the recombination rate. By minimizing the number of dangling bonds, surface passivation enhances the efficiency and performance of solar cells.

 

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