[scientizscht (OP)]

Hello!

Are there materials that allow light to pass from one side? And not the other?

Thanks!

[Bored chemist]

Does this count as a "material"?
https://en.wikipedia.org/wiki/Optical_isolator

[evan_au]

There always the "one-way mirror" of the TV cop shows: An obtrusive mirror taking up one side of the interview room, separating the interview room from the observation room. The observation room houses cameras; detectives can hold private conversations about the case, while watching the suspect squirm...

This works by having a partially-silvered mirror, so some of the light from the interview room passes into the observation room. The observation room is kept dark, so no light from the observation room passes into the interview room (or so little that it is totally obscured by the mirror's reflection back into the interview room).
See: https://en.wikipedia.org/wiki/One-way_mirror

[alancalverd]

We also use black mesh (in extremis, a nurse's stocking) to suppress reflected glare from glass screens. The ambient light has to pass through the mesh twice so is attenuated by a² (where a is the attenuation ratio of the mesh) but the wanted light from the screen only passes through once, thus improving the effective contrast ratio by a factor of a.

I once used the "nurse's stocking" trick literally, in an operating theatre where the x-ray display was on its last legs and the ambient was brighter than daylight. Modern medical and avionics screens have a built-in mesh.