in the DSSC, when a photon with an energy higher or lower than the level of homo is falling, what will happen in the system? For example, a photon with an energy corresponding to the wavelength at homo (e.g. 500 nm) will excite the dye particle to the Lumo level, right? However, what will happen in the case of energy with a length of 400 nm? or 100 nm, 800 nm?
If the dye has a lot of absorption spectrum, it will still generate only LUMO-level energy at its wavelength, right?
Mikita Davykoza
The HOMO / LUMO orbitals are very simplistic for a dye molecule that has a large number of orbitals. However, this is enough to answer your question. The difference in electron energies at NOMO-LUMO indicates the weight of the absorption range of the molecule. Let us assume that the dye absorbs in the range of 300 - 600 nm. If a photon with a wavelength of 400nm falls on it, then its absorption energy
Planck's constant x frequency (300) - Planck's constant x frequency (600) = ...
Photons with wavelengths of 200 and 650 nm will not be absorbed by the dye.
r
Dear Yuri Mirgorod
Thank you for your answer!
This means that the absorbed photon energy will always be constant: E = LUMO-HOMO? And the residue will be released in the form of heat or light (luminescent)?
I could not understand it, because on the page among the requirements for the dye it is marked ("1. Firstly, the dye should be luminescent"):
https://nanoscalereslett.springeropen.com/articles/10.1186/s11671-018-2760-6
And then the height of the absorbance will further illustrate the expected current in the circuit? Regarding the voltage, the matter is clear and understandable.
Regards,
MD
P.S. Огромное спасибо, я долго над этим сидел.
Kindly check https://www.researchgate.net/publication/270123509_Absorption_Spectra_of_Natural_Dyes_and_Their_Effect_on_Efficiency_of_ZnO_Based_Dye-Sensitized_Solar_Cells
Also check https://www.nature.com/articles/s41598-019-53534-2
Dear Mikita Davykoza ,
welcome,
There is some unclear points in your question. Please let me elaborate on some concepts related to the phot absorption of any semiconductor materials including the Dies. The dies are characterized by a molecular band structure. There is the homo level which is the highest occupied valence level. There is also the lumo level which is the lowers empty molecular level.
So electrons are transferred from homo to the lumo level when subjected to photons with energy equal to the difference between the lumo and homo levels as hinted before. In solid sate materials the single levels broadens to a band and therefore the material absorbs a band of photons covering specific range of the wavelengths.
So this material absorbs a band of wave lengths around the original homo and lumo levels of the isolated ,molecules.
For more information please refer to the paper in the link:Article Modeling of organic semiconductor conduction parameters with...
Best wishes
Dear Abdelhalim abdelnaby Zekry
Good evening!
Thank you for such a clear and understandable explanation. This was useful information for me.
Best R.