Science Fair Project help plox

[AustinBlyat]

So this isn't really a computer thing... but i hope someone out there can help me. My science fair project is using body temp/heat to charge a phone. I bought peltier tiles and a powerbank circuit (based on what i watched on yt) and soldered the red cable to b+ (from tile to circuit) and the black tile to b-, again following the video. But it doesn't work, im not sure if its because the temperature differences aren't extreme enough but im not sure how to keep one side hot while the other cold. if anyone could help me that would be deeply appreciated

thanks