You have to calculate thermal wavelength. If th.wavelength is smaller than 5 nm you can not have the thickness you request because of uncertainty principle which yields to confinement, and if it is higher than 5nm than yes.

Dear Nithya K S ,

I would rather see the issue from another perspective.

One may ask what is the minimum thickness required to get continuous layer of the material above the absorber layer which is made out of organic molecules that are normally large in size. As spin on is normally used can one produce such small thickness with homogeneity by this deposition technology.

I think you have to search in the literature for the minimum reproducible thickness of the transport layers.

Quantum mechanical transport is prevailing when the dimension of the space is equal to the de Broglie wavelength

Lambda = h/ mv where m is the electron mass and v is its velocity.

With v=10^5 m/s, m = 9.1x 10^-31 kg and h = 6.62607015 × 10−34 joule second.

one gets Lambda= 7.2 nm which means that the quantum mechanics is prevailing. trapping and tunneling are possible. but because the presence of neither a quantum well nor a a barrier they will flow to the metallic contact where they will be collected.

You have to notice that the transport layer energy levels must be such that it extracts the charge carriers from the active layer and deliver it to the metal layer.

There is no barrier in their path to the intended transport layer.

You can compare your results with the paper in the link:

Article Numerical study of organic graded bulk heterojunction solar ...

and the paper:

Article Possible efficiency boosting of non-fullerene acceptor solar...

Best wishes

Nithya K S , regarding the question in the title: There is no doubt that it is possible.

There are quite many experimentally measured solar cells consisting of separate layers of P3HT and PCBM (and/or analogs of both) with thicknesses from 2 nm each, and probably thinner. The problem of this type of solar cell is too low absorption. Even with unrealistic 100% quantum yield one cannot have high total efficiency in such a case. Well, this is a case of one dimensional confinement and 2-dimensional conductivity.

There were other publications with dendrimer type of fullerene chains, forming 2-dimentional confinement, thus it is also possible.

Another well known example of conductivity in 1-d and 2-d confinement conditions is graphene and carbon nanotubes with even smaller size.

So, yes it is possible. I have never seen any publications showing experimentally measured distribution of PCBM in BHJ cells. But last years I do not follow publications in this area, unfortunately, and cannot say if it is known to happen.

Colleges have well described the de Broglie wave as criterium of confinement effects for consideration in your model.