HI. I got some question about the derivation of the I-V characteristic in a solar cell.(adsbygoogle = window.adsbygoogle || []).push({});

The first step is to solve the minority carrier diffusion equation with appropriate boundary conditions: at the edges of the cell and at the edges of the depletion zone.

At the edges of the d.z. the conditions for the concentrations p_N and n_P can be found using quasi-Fermi levels....

1) Suppose to be in case of forward applied voltage V. In the quasi neutral regions, far from the d.z, and into the d.z., the quasi-Fermi levels are constant. This means that here currents J_p and J_n equal to 0. How is it possible to have currents just in teh little spaces out of the d.z. when a votage is applied?

2) Why qV= F_n - F_p ?

In thee next step of the derivation, they integrate the electron continuity equation over the d.z. ,

dJ_{n}/dx = q[ R(x) - G(x)]

with R recombinatio rate ad G generation.

For R they consider just midgap single level trap mechanism. They keep a point X_{m}inner the d.z. at wich p(x_{m})=n(x_{m}) and then consider R(x_{m}) for the whole d.z.

3) Does is exst a point xm where p=n?

If someone would like to answer id be really glad. Bye

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Pn junction in solar cell case

Can you offer guidance or do you also need help?

Draft saved
Draft deleted

**Physics Forums | Science Articles, Homework Help, Discussion**