Most dishwashing liquids are strong detergents. They cut grease better than plain soaps. OTOH, they are much too strong for most plants, and can burn the leaves. In addition, the treatment should be applied when the plant is not in full sun, because the water droplets can act as little magnifying glasses. Ever start a fire as a kid, using a magnifying glass?
It sounds like you did everything right, but used the wrong products. I like Dr. Bronner's unscented liquid Castile soap for this purpose, but you can use Ivory or even Murphy's Oil Soap. You can even use a bar soap by shaving bits off and soaking them overnight in water. Just make sure it's a pure soap, like Castile or Ivory. I don't know that it would be a problem, but I wouldn't use something like Irish Spring or Dial. That's JMO, though, as I've never tried it. I did use Dawn the first time I made a soap solution to kill insects, and I burned all the leaves on one branch of the tree I was treating. I'm sorry it happened to you, as well.
I don't know alot about pepper plants, but do NOT put fertilizer on them or start to give them more water. That will only make matters worse. The plants won't have any use for extra food, so it will just sit in the soil and damage the roots. With no leaves to transpire moisture, extra water will just sit in the soil and rot the roots. I think just keeping them on the same schedule you had them on would be fine. Cut back on watering if the soil looks like it's staying wet longer than usual, and do not fertilize.
Best of luck to you!
"Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too?" - Douglas Adams