Semiconductor polymers P3HT

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Summary:

In Fact, I tried to understand the result (Figure 3) of a paper named "A general relationship between disorder, aggregation and charge transport in conjugated polymers", but because of some special concept I could not understand. would you please explain the result of Figure 3?
Thanks

Main Question or Discussion Point

"In the case of negligible paracrystallinity, the density of states (DOS) of the 1D pi-stack depends on the amount of on-site disorder generating a Gaussian tail of states extending into the bandgap (Fig. 3a). Typical pi-stacks of conjugated polymers exhibit moderate amounts of paracrystalline disorder (g >5%; see below). Under these conditions, the DOS of the aggregate is hardly affected by on-site disorder and is determined by the amount of paracrystallinity (Fig. 3c,d). The spatial extent of the calculated wavefunctions for the disordered stack (Fig. 3e-h) shows that disorder-induced states that lie deeper into the DOS tail are increasingly localized. Even states within the originally `delocalized band' become more localized with increasing paracrystallinity. In the limit of large positional disorder (g ~10%), the distinction between band and tail disappears: a single broad distribution of localized states with a monotonically decreasing DOS extends into the bandgap, reproducing well-known results of electronic structure theory of amorphous materials34,35. In the intermediate paracrystallinity regime (g ~3-7%) we observe a coexistence of localized and delocalized states, indicating that in paracrystalline aggregates charge is transported by a mechanism where mobile charge is temporarily trapped in localized states, akin to multiple trapping and release."
 

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  • #2
Dr_Nate
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There's many high-level concepts in there.
What's your background knowledge on this subject?
 
  • #3
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There's many high-level concepts in there.
What's your background knowledge on this subject?
polymers
 
  • #4
Dr_Nate
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polymers
Do you understand the concepts of electronic band structures, density of states, and band gaps well?
 
  • #5
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Do you understand the concepts of electronic band structures, density of states, and band gaps well?
I read about band gap and DOS.

DOS: The density of state function describes the number of states that are available in a system and is essential for determining the carrier concentration and energy distributions of carriers within a semiconductors.

I did not understand : One-site disordered Localization length Eigenstates of the disordered Hamiltonian
If you can kindly tell me about the concept and refer me to a book or paper I appreciate it.
 
  • #6
Dr_Nate
Science Advisor
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To truly understand this stuff you're going to need a course in quantum mechanics to start to understand wave functions.
I did not understand : One-site disordered Localization length Eigenstates of the disordered Hamiltonian
If you can kindly tell me about the concept and refer me to a book or paper I appreciate it.
I would need to read the paper to truly understand what's going on but I'll tell you what I think they've done. They've used quantum mechanics to solve a particular model that they made up. Localization length probably refers to a measure of how far the electron wave function's weight is distributed away from the lattice (or maybe atomic site).
 
  • #7
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To truly understand this stuff you're going to need a course in quantum mechanics to start to understand wave functions.

I would need to read the paper to truly understand what's going on but I'll tell you what I think they've done. They've used quantum mechanics to solve a particular model that they made up. Localization length probably refers to a measure of how far the electron wave function's weight is distributed away from the lattice (or maybe atomic site).
Thank you so much for your reply. I think that they wanted to show the effect of disorder in polymer structure on DOS. I did not understand what they concluded from that?
would you please explain more about localization length?
They want to show relationship between disorder/order and charge transfer in P3HT. They found that short-range order improve charge transfer.
 
  • #8
Dr_Nate
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You're going to have to read their conclusions for that.
 
  • #9
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There is not any conclusion part that explain specifically mention the result of this picture.
 

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