You can't tint your windshields for a few reasons:
1. Safety-Glass is designed to shatter. Tinting will prevent it from shattering and you could die easier if you go through the windshield.
2. Cops need to see your face. As well (even though still not legal) photo enforced intersections need to see your face.
3. Night time driving is seriously affected by tint... The windscreen is the worst place for it.
Aside from that, there isn't any "film" that could do this. At least not on the market. OLED screens in the future would work, but still, not ready for public yet.