where [[tau].sub.e] is the effective carrier lifetime, [alpha] the absorption coefficient of the semiconductor at the illumination wavelength, [P.sub.0] the light intensity, [omega] the angular frequency of the light, [??] the reduced Planck constant, R the reflectivity of the wafer, and Ld the ambipolar
diffusion length calculated using the diffusion characteristics of both electrons and holes [25].
This not only enhances the interpenetrability of the donor/acceptor blends but also increases the interfacial area of BHJ solar cell systems, thus increasing exciton
diffusion length and enhancing their dissociations [61].
Further, as the
diffusion length of these excitons is only of few nanometres (approximately 8-10 nm) before it will relax back to the ground state so; the heterojunction for excitons splitting should be within the excitons diffusion limit (i.e., as close as possible to the photo generation point) [4].
By tracking down the rapid motion of electrons in the material, they have been able to determine the
diffusion length -- how far electrons can travel without getting trapped by imperfections in the material -- as well as mobility -- how fast the electrons can move through the material.
The exciton
diffusion length of PA is longer than 1 micrometer [4]; therefore the bilayered structure based photovoltaics are workable [1-4].
The [n.sub.d] values for simulated data of SS304 varied greatly from 0.73 to 0.47, meaning the diffusion process shifted from a finite
diffusion length due to the oxide growth to an infinite tangential diffusion.
The parameter k represents the ratio of the Debye length to a
diffusion length scale ([I.sub.D]) given by
[40] and evolved from Fick's law of (4) when assuming that the concentration profile along the
diffusion length x is linear: