From the image above, we can observe that N-type silicon is red and includes electrons represented by black circles.
P-type silicon is blue, it contains holes, and they are represented by white circles.
The power supply across the p-n junction forward-biases the diode and pushes electrons from n-type to p-type. Push the hole in the opposite direction.
The electrons and holes at the junction are combined.
As electrons and holes recombine, photons are released.