Donor-Bridge-Acceptor (DBA) or Donor-Acceptor (DA) architectures are widely employed protocols to achieve Charge Transfer (CT) in organic semiconductors. Lower Exciton Binding energies (EBE) are required to attain higher efficiencies in Solar Cells.
By exploiting the dipole moment changes we design Donor-Electret-Acceptor moieties which enhances hole and electron distance upon excitation favoring higher CT and CT distance, reducing EBE, plausibly enhancing solar cell efficiencies in the following article.
Article Novel Donor–Electret–Acceptor Framework for Higher Charge Tr...
reduce the high top surface recombination was accomplished by reducing the number of dangling semiconductor bonds at the top surface
Hello Vikramaditya Talapunur
In order to improve solar cell efficiency, we need to improve the exciton conduction process in the bulk far from the interface and the exciton dissociation processe at the interface.
In this purpose we need to fulfill two conditions:
1. to ensure a sufficient exciton binding energy in order to avoid excess exciton dissociation in the bulk of the material before reaching the interface,
2. to ensure a sufficient band lineup (offset) at the interface so that the corresponding electrostatic electric field is sufficient to break the exciton bonding and make the electron free to diffuse on one side of heterojunction interface and make the hole free to diffuse on the other side of the interface.
Therefore, there is a need of fine tuning these two antagonist processes to improve the efficiency of the solar cell.
Best regards,
Professor Abderrahmane Kadri
You can see this research:
https://pubs.acs.org/doi/10.1021/am402744k
Dear Vikramaditya Talapunur ,
This is a good question and prof. Abderrahmane Kadri gave an answer to it.
As said the main problem in organic solar cells is the too high binding energy in the excitons and their short lifetime in the material. This leads to a very short distance to the interface between the donors and acceptors in order to separate the exciton before it recombine. In fact the acceptor material build an attractive electric field on the electrons of the excitons to dispatch them further to the ETL.
So, as you see the separation is affected by the attracting electric field of the acceptor. The exciton diffusion length dictates the distance between the dodnors and acceptors. If there is an electric field agent or conveyor between the two one can further increase the distance between the donors and acceptors. This leads to smaller interface area between the donors and acceptors which is the main cause of recombination losses.
This is really a good idea.
Best wishes
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