It sounds like you may have a leaf blight. Copper sulfate is sometimes recommended for fungal infections like this, but as peppers are an edible crop and I am not sure of the diagnosis I would not recommend spraying your plants. Instead, remove the worst of the leaves, try to increase air circulation, and do not overwater. Peppers like full sun in the warmest place in your garden. With some luck they will snap out of this fungal infection in time for a fall harvest. Keep growing, Marianne Binetti