Well, either the triangle is an unusually efficient piezo generator (in which case you don't have to "charge" it per se, but you do have to park your car on it every night), or, in the "middle layer consisting of silicon and other elements", the other elements are all highly radioactive.

But seriously, is there any well-known type of electronic component for which 'squat triangular prism' is the most efficient shape? Like, I've never taken apart a computer or piece of audio gear, no matter how old, and said to myself "whoa! I'd better be careful. Lot of triangles in there."