Excitons diffusion length

The second type of solar cell is based on a /m-heterojunction in analogy to semiconductor devices [274]. Excitons generated by light, diffuse and dissociate at the interface between a hole and an electron-conducting material. The optimum layer thickness was calculated to be 1.5 times the exciton diffusion length [275]. 

Lunt RR, Giebink NC, Belak AA, Benziger JB, Forrest SR (2009) Exciton diffusion lengths... 

Such bilayers were studied by photoluminescence, with a view to extracting the degree of photoluminescence quenching induced by a thin acceptor layer on the polymer [18]. Studies of photoluminescence quenching in bilayers have corroborated the picture derived from studies of photoelectrical performance. The short exciton diffusion length in PEOPT is 5 nm, consistent with both PL quenching and photodiode performance. 

Thus, a plot of lh] versus Ha should be linear with an intercept-to-slope ratio of , the exciton diffusion length. For the case where 1/a , Eq. (7) becomes... 

Mulder (1968) described photogeneration in anthracene by a surface-enhanced exciton model. Figures 27 and 28 show the photogeneration efficiency and singlet state absorption coefficient. According to Mulder, when the exciton diffusion length l and the absorption depth, //a, are much less than the thickness, the photogeneration efficiency is... 

Harima et al. (1989) measured the photogeneration efficiencies of 5,10,15,20-tetraphenylporphyrin (TPP) and its Zn complex (ZnTPP) doped with tetracyano-quinodimethane (TCNQ), o-chloranil (Chi), phenothiazine (Pz), and I. TCNQ, Chi, and I are electron acceptors while Pz is a donor. The porphyrins were selected on the basis of differences in exciton diffusion lengths (Tanimura et al., 1980 Yamashita et al., 1987) and oxidation potentials (Felton, 1978). The photogeneration of I doped ZnTPP was described by a direct ionization process via a singlet state of ZnTPP and ascribed to a reduction of the electron-hole recombination rate in the depletion layer. For TPP doped with Chi, Pz, or I, the results were explained by exciplex dissociation (Loutfy and Menzel, 1980). For... 

Kroeze JE, Savenije TJ, Vermeulen MJW, Warman JM. (2003) Contactless determination of the photoconductivity action spectrum, exciton diffusion length and charge separation efficiency in polythiophene-sensitized TiOj bilayers./Rfc yr Chem B 107 7696-7705. 

---