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We can define the Incident Photon to Converted Electron (IPCE) for a solar cell as the ratio of photons that strike the solar cell to the number of electrons that flow out of the cell.

Hence, we can express it as (Absorptance as a function of wavelength) x (Some internal quantum efficiency term), if a dye is mediating the light absorption.

Then, we would expect the IPCE to be less (and directly related) to the absorptance as the internal quantum efficiency must be less than unity.

However, in practice this isn't true and despite having low absorbance (which is associated with absorptance) at a certain wavelength, it still has a high ICPE. (cf. ICPE and on TiO2 at 550nm in the diagram).

Why can the IPCE still be high despite low absorptance?

IPCE and absorbance

Frederic Thomas
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UserPhysics
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  • I would guess because of incident photons that are reflected? –  Nov 10 '19 at 14:16
  • By assuming that incident photons are not reflected, we maximise the absorptance value. However, the absorptance values are still low, so this cannot account for it. Also, reflected photons cannot contributed to electron release, hence won't increase IPCE – UserPhysics Nov 11 '19 at 09:41
  • Can you add some numbers to your y-axis so we know exactly the magnitude. Also it’s crucial to know what the thickness of dye containing layer is. My only other guess, is that the solar cell has some form of light trapping (that allows multiple passes of light rays through the absorber). – boyfarrell Nov 24 '19 at 12:41

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