Exciton generation rate

This is given by g = gexdex, where gex is the exciton generation rate and /ex the exciton dissociation probability. The position dependence of gex can be found by solving Maxwell s equations for light absorption in the thin, layered device structure. Because of the low thicknesses and low dielectric permittivity, absorption is strongly influenced by optical interference. In an effective medium, tj x can be treated as a... 

In the absence of lasing with steady-state conditions, the exciton generation rate equals the sum of the relaxation rates and the population in level 2 is negligible (N3 0), giving a constant population difference (N) of... 

A simple example of this is the case of a molecule (modeled as an oscillating dipole) close to a perfect mirror. If the dipole is parallel to the mirror, destructive interference between directly emitted light and reflected light causes a reduction in the radiative rate. In the presence of competing nonradiative decay processes, this leads to a reduction in the efficiency of emission. The variation of radiative rate with position and orientation for a molecule within an arbitrary planar dielectric structure has been modeled by Crawford.81 This model has been applied to polymer LEDs by Burns et al.,82 and Becker et al.,83 who predict significant variations in the efficiency of radiative decay in polymer LEDs depending on the distribution of exciton generation within the device. 

Pth is the pumping optical power necessary to reach threshold and is linearly proportional to the threshold generation rate of excitons, Gth- Thus, if the introduction of an analyte causes the overall relaxation rate (732) to change then the quenched laser power becomes... 

Rate of photon emission Re 732 Rate of exciton generation G re... 

Figure 5a. The charge generation exhibits a threshold-like electric field dependence with an onset at 0.7 x 10 V/cm, showing that there is a substantial potential barrier (several tenths of an eV) between the exciton and charge pair states, which is reduced by the electric field. The charge pair generation rate is not constant in time, but decreases with time as y(0( o typical for a random system, as a result of a...

The formation of multiple electron-hole pairs (excitons) are identical to multiple exciton generation, that is, ehpm = /meg- b carriers are formed upon dissociation of the excitons. The generation rate of excitons /tmeg competes with the radiationless deactivation of an electron down to the bottom of the conduction band The ratio between these two rates is given by the factor P which is related to tj EG by [180]... 

The recombination rate Ptlx, which is defined as the number of generated exci-tons in A/ divided by the number of generated excitons in At plus the number of minority carriers passing through the device in At, for an unbalanced LED (where j(x) jp(x) 3> j (x) and pp pH) is given by the following equation ... 

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