Coulomb capture radius

Consider first the fate of an H+. In a region with an average density nB of B- ions, each with a Coulomb capture radius of the order of 50A [from (17)], the mean lifetime rc of an H+ with respect to capture into BH will... 

For an organic semiconductor blend with an average dielectric constant of 3, this Coulomb capture radius is 19 nm at room temperature, which is somewhat larger than the typical exdton diffusion length of 10 nm. Of course for this estimation it... 

This process is referred to as auto-ionization (AI). It does not follow that all AI transitions lead to completely uncorrelated carrier pairs. Most of the emitted electrons will thermalize within the Coulomb capture radius of the geminate positive ion, forming a transient charge-transfer state that can either decay to the ground state or dissociate by the absorption of ambient energy. Following Jortner (3), the wavefunction of such an AI state can be written as... 

The value of 2q is referred to as the Coulombic capture radius r, and corresponds to the distance at which the kinetic energy of the diffusing particle is equal to the Coulombic attractive potential energy. For an electron moving with thermal energy kT,... 

Equations (10.2) and (10.3) describe the process when a pair of opposite charges encounter each other in space and recombine with the help of Coulomb attraction. According to the classical bimolecular recombination model, when the mean free path of charges in a material is smaller than the Coulomb capture radius bimolecular recombination will take place. The typical mean free path of organic semiconductors is about 1-2 nm, which is much smaller than r (10-20 nm at room temperature ), therefore bimolecular recombination is universally present in OSC devices. ... 

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