Best Night clock app that will pop up when i put the note 5 on charging??

i was trying so many apps as a night clock to my note 5 so the screen will be so dimmed and i see the clock..
for example this one

https://play.google.com/store/apps/d...ht_clock&hl=en

but the problem is i can't find an app with very dimmed screen that will pop up by it self when the note 5 is on charging...
and free app with no adds on it.....


please any good suggestions ??