Lightly grease a 5-quart (or similar sized) slow cooker insert with nonstick cooking spray.
In a small bowl, combine the paprika, pepper, salt, garlic powder, coriander, red pepper flakes and thyme.
Place the green peppers and onions in the bottom of the slow cooker. Sprinkle 1 teaspoon of the seasoning mixture over the top.
Toss the chicken with the rest of the seasoning mixture. Layer the chicken on the top of the green peppers and onions.
Pour the chicken broth inside around the edges of the crockpot.
Cook on low for 5-7 hours until the chicken is tender (over cooking the chicken may make it a bit dry so only cook it until the chicken is cooked through and tender). Remove the chicken from the slow cooker and shred into pieces. Set aside.
Using a slotted spoon, remove the peppers and onions to a plate. Pour out all the liquid into a bowl or liquid measure.
Place the chicken, peppers and onions back in the slow cooker and toss. Pour in enough liquid to keep the chicken moist (but not soggy) – about 1/4 cup to start and add as needed. Keep the slow cooker on warm or low until ready to serve.
Toast the buns under the oven broiler. Place chicken and peppers on each half of a bun and top with Provolone cheese. Broil until the cheese is melted and slightly bubbly. Serve warm.