@chrono4548 the only way to do this while the screen is off is to root the phone and install the appropriate Xposed framework to handle NFC while the screen is off. If you've already rooted then it's easy enough to set up but if you haven't rooted yet I'd suggest looking into the possible ramifications for you and your device - on some devices you can permanently disable features that the manufacturer requires the phone to be in a standard state for.
C