Source: Nachrichten aus der Wissenschaft » idw

The Generation of Current in a Solar Cell

Understanding the Light-Generated Current

The generation of current in a solar cell, also known as the “light-generated current,” involves two essential processes. The first process begins with the absorption of incident photons, which leads to the creation of electron-hole pairs within the solar cell. For electron-hole pairs to be generated, the energy of the incident photon must exceed that of the band gap. However, these electron-hole pairs are only temporary and will exist for a duration equal to the minority carrier lifetime before recombination occurs. If recombination happens, the light-generated electron-hole pair is lost, resulting in no current or power generation.

The Role of the p-n Junction

The second crucial process involves the collection and separation of these carriers by the p-n junction. The p-n junction spatially separates the electron and the hole, preventing recombination. This separation is facilitated by the electric field present at the p-n junction. When the light-generated minority carrier reaches the p-n junction, it is swept across the junction by the electric field, transforming into a majority carrier. If the emitter and base of the solar cell are connected (short-circuited), the light-generated carriers flow through the external circuit, enabling the generation of current.

By understanding these processes, we can appreciate how solar cells harness light energy to produce electricity efficiently.

Source: ResearchGate