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Again, I'm a physicist turning to chemists (so bear with me). So I've been measuring some materials by changing the wavelength of the incident light on the material and I have a detecting tip like in the diagram below:

enter image description here

And I might get a response that looks like this

enter image description here

Both materials have the same HOMO (organics) / Work Function (Metals). For example, I hardly detect any photoelectrons (emitted electrons) from stainless steel, but loads from copper (both roughly 4.5eV).

However, I am more interested in organics, why might some substances (e.g certain blends of perovskites) emit more than others (even if I have exceeded the energy required to lift an electron from the HOMO to the vacuum level)?

I thought it might be related to Density of States in metals, but this effect is also found in non-lattice molecules.

Could this be related to the related to the reversibility of the reaction (one scientist mentioned this off-the-cuff, but I never managed to catch his name to ask him to explain it further)? Essentially his idea was that molecules that can easily lose or win an electron by an outersphere process (?) (which are likely to have a clean reversible CV voltagramm) and exhibit a strong response in spectroscopy where an electron is given.

I do realise this is a bit more open ended than most questions here on Stack Overflow. But any advice or suggestions is appreciated.

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    $\begingroup$ Three words - density of states. $\endgroup$ – Jon Custer Jul 26 '17 at 13:46
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    $\begingroup$ I suggest that you google "photocathodes" for a lot more information. Most public university libraries have some public access which will allow you to get articles from many pay sites for free. $\endgroup$ – MaxW Jul 26 '17 at 15:05
  • $\begingroup$ Do you mean organic molecules blended with perovskite? You have one perovskite, and you change the organic composition? $\endgroup$ – Alchimista Jul 26 '17 at 22:36

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