What is exciton diffusion length?

The exciton diffusion length can be calculated as LD = (Dτ)1/2, where D is the diffusion constant given by D = α/(8πR) (three-dimensional diffusion model), R is the annihilation radius of singlet excitons. The annihilation radius cannot be easily measured and generally assumed to be 1 nm21,41,42,43.

What is exciton recombination?

As a result of absorption of photons of energy equal or greater than the band gap energy of the semiconductor, the excitons (electrons and holes) are generated in the conduction and valence band, respectively. This is called exciton recombination. The same phenomenon is also present in an organic semiconductor.

What is exciton absorption?

An exciton is a bound state of an electron and an electron hole which are attracted to each other by the electrostatic Coulomb force. An exciton can form when a material absorbs a photon of higher energy than its bandgap. This excites an electron from the valence band into the conduction band.

What is exciton mention its types?

This is termed as exciton. In organic materials two models are used: the band or wave model (low temperature, high crystalline order) and the hopping model (higher temperature, low crystalline order or amorphous state). Energy transfer in the hopping limit is identical with energy migration.

How many measurements of exciton diffusion in organic semiconductors?

An extensive table of more than a hundred measurements of the exciton diffusion length in various organic semiconductors is presented. Finally, an outlook of remaining challenges for future research is provided. Please wait while we load your content…

How is exciton diffusion related to energy transfer?

Special attention is devoted to the temperature dependence of exciton diffusion and its relationship to Förster energy transfer rates. An extensive table of more than a hundred measurements of the exciton diffusion length in various organic semiconductors is presented. Finally, an outlook of remaining challenges for future research is provided.

What is the diffusion length of an organic solar cell?

The diffusion length of excitons in organic electronic materials is typically on the order of 10 nm. In order for most excitons to diffuse to the interface of layers and split into carriers, the layer thickness should be in the same range as the diffusion length.

How are excitons scattered by phonons in a semiconductor?

If this coupling is weak as in typical semiconductors such as GaAs or Si, excitons are scattered by phonons. However, when the coupling is strong, excitons can be self-trapped. Self-trapping results in dressing excitons with a dense cloud of virtual phonons which strongly suppresses the ability of excitons to move across the crystal.