Place the chicken thighs in the bottom of the slow cooker.
Add the sliced bell peppers and onion on top of the chicken.
Pour the pineapple chunks and their juice over the vegetables and chicken.
In a small bowl, stir together the soy sauce, brown sugar, minced garlic, grated ginger, and black pepper.
Pour the sauce mixture evenly over everything in the slow cooker.
Cover and cook on low for 6 to 7 hours, until the chicken reaches an internal temperature of 165°F.
Serve the chicken, peppers, and pineapple over cooked rice and top with sliced green onions.