I think you're confused. OLED stands for Organic Light Emitting Diode. Note the "Light Emitting" part and you'll quickly realize that any OLED film applied to your windows would really blow chunks.
I can just imagine driving down the road, the sun setting ahead of you, getting in your eyes. So you dial up the current to the OLED film on your windshield. Suddenly, you slam into the guardrail at 65mph because you forgot that OLED means you just turned your entire windshield into a wall of light.
I think you mean e-ink film. It uses charged, suspended capsules with different colors on each side of the charge. As the film layer is charged one way, the capsules rotate in suspension such that the desired color is rotated to the desired orientation. Even that stuff wouldn't work that great as a window tint. You'd still have major haze issues.
Frankly, I think the whole idea of DIY electric window tint is half-baked. I have enough problems with minor glitches in my CarPC. The last thing I need is a something that could cause all of my car windows to become totally opaque, simply because of some faulty PIC code, or a short, or a vibration induced component failure, or... You get my drift.