Source: ResearchGate

Understanding Silicon Solar Cell Efficiency

Maximizing Carrier Collection

In silicon solar cells, efficient collection of light-generated carriers is crucial for optimal performance. To achieve this, both surface and bulk recombination must be minimized. Two key conditions for effective carrier collection are:

1. The carrier must be generated within a diffusion length of the junction to reach it before recombining.
2. In the presence of localized high recombination sites, such as unpassivated surfaces or grain boundaries, the carrier must be generated closer to the junction than to the recombination site.

Impact of Recombination Sites

Localized recombination sites at the front and rear surfaces of a silicon solar cell influence the collection probabilities of photons with different energies. For instance, blue light, with its high absorption coefficient, is absorbed near the front surface. If the front surface has high recombination, it may not generate minority carriers collectible by the junction. On the other hand, high rear surface recombination primarily affects carriers generated by infrared light, which can penetrate deeper into the device.

Quantum Efficiency

The quantum efficiency of a solar cell measures the impact of recombination on light generation current. In silicon solar cells, the quantum efficiency varies based on the presence of recombination sites. It provides insights into how effectively the cell converts incident light into electrical current.

Source: Fluxim

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