In a p-n junction

1. The potential of the p and n-sides becomes higher alternately
2. The p-side is at higher electrical potential than the n side
3. The n-side is at higher electrical potential than the p-side
4. Both the p and n-sides are at the same potential

For conduction, p-n junction must be forward biased. For this p-side should be connected to higher potential and n-side to lower potential.