This is a good question. American culture is so complex that it does not have a monolithic image of African American teenagers. Let me explain this diversity.
Just look at the major television shows of the past few decades. This will clearly show that African American teens are depicted in many different ways. For example, if you think of Steve Urkel, he was depicted as a nerdy, intelligent and oddly charming teen. If you think of Will Smith from the show Fresh Prince of Bel-Air, he was depicted as a smooth, cool, and a very handsome teen. His cousin was just the opposite.
The same can be seen in the movies. The roles are not monolithic at all. To put it in short, the world has drastically changed.
When it comes to music, often African American teens are portrayed for their sex appeal, but this is not something that apply to African American teen, but all teens in general.