There are many varieties of peppers, from sweet to mild and super hot!
Bell peppers are sweet, Japaleños are mild (in my opinion), and the hot peppers I know and use are: Habanero, Scotch Bonnet and Madame Jeannette (Surinamese).
To reduce the “heat” of the fresh pepper, you can
- remove the seeds
- add a little bit more sugar
- partially slice the pepper instead of cutting it up, and cook whole
- remove the whole pepper once the chicken is done
- cook whole uncut pepper to release aroma, without the heat