Actually I need a photocathode which should wok in vacuum and I've seen many interesting materials but which are used in photochemical cells. But I don't know if such materials would still be good emitters in vacuum or not.
Actually I need to find a simple material which could be coated easily on large sufaces, be a good photoemitter in sunlight and be stable in the air, at least for a few days or so. I need to be able to emit currents larger than 1mA/cm2 , the photocathode is working in vacuum.
My confusion comes from the following fact: I don't know if photoemission is affected by the fact that the material is submersed in a liquid (normally it could be). I've seen in some publications that CuO can be used as a photoemitter in a photochemical cell (having a good efficiency and being more stable than Cs compounds etc.) and I wanted to know if it could also work efficiently in vacuum.
If you could help me with some information I'll be very grateful.