I actually prefer to dry peppers out on a counter, or flat surface, in the sun. Turn them once or twice a day to keep from rotting. If you still want to do it in the over, I would recommend the lowest setting until they are dry. Flip them on occasion. Still the best method would be to sun dry them.
Here is an article for other methods: https://www.gardeningknowhow.com/edible/vegetables/pepper/drying-hot-peppers.htm