Conjugated polymer:fullerene bulk

A significant increase in the forward current and in the FF is observed for conjugated polymer/fullerene bulk heterojunction solar cells upon insertion of a thin layer of LiF between the organic layer and the Al electrode (negative electrode of the solar cell), as shown in Fig. 5.37a and b. 

The observed experimental result that Voc decreases linearly for bulk heterojunction solar cells allows us to conclude that, at least in the high temperature range (T > 200 K), these solar cells may be described by a diode model with Ip exp(E/kT). Here E is a parameter analogous to Eg for conventional semiconductors. For conjugated polymer/fullerene bulk heterojunction solar cells, E should correspond to the energy difference between the HOMO level of the donor and the LUMO level of the acceptor components of the active layer [as also suggested by the extrapolated value of V oc(0 K)]. 

Hoppe H, Glatzel T, Niggemann M, Hinsch A, Lux-Steiner MC, Sariciftci NS (2005) Kelvin probe force microscopy study on conjugated polymer/fullerene bulk heterojunction organic solar cells. Nano Lett 5 269... 

Hoppe H, Arnold N, Meissner D, Sariciftci NS (2004) Modeling of optical absorption in conjugated polymer/fullerene bulk-heterojunction plastic solar cells. Thin Solid Eilms 451-452 589... 

C.J. Brabec, et al.. Tracing photoinduced electron transfer process in conjugated polymer/fullerene bulk heterojimctions in reed time. Chemical Physics Letters, 2001. 340(3-4) p. 232-236. 

Mozer, A.J., G. Dennler, N.S. Sariciftci, M. Westerling, A. Pivrikas, R. Osterbacka, and G. Juska. 2005. Time-dependent mobility and recombination of the photoinduced charge carriers in conjugated polymer/fullerene bulk heterojunction solar cells. Phys Rev B 72 035217. 

Several organics, e.g. pristine poly(3-octylthiophene), polyfluorene, bifunctional spiro compounds and polyphenyleneethynylene derivative, have been used for fabricating photOFETs. Responsivity as high as 0.5-1 A/W has been achieved in some of these transistors. We have already discussed the bulk heterojunction concept in Chapter 5. The bulk heterojunctions are fabricated using acceptor materials with high electron affinity (such as C<5o or soluble derivatives of C6o) mixed with conjugated polymers as electron donors. PhotOFETs based on conjugated polymer/fullerene blends are expected to show... 

Hoppe H, Niggemann M, Winder C, Kraut J, Hiesgen R, Hinsch A, Meissner D, Sariciftci NS (2004) Nanoscale morphology of conjugated polymer/fullerene based bulk-heterojunction solar cells. Adv Fund Mater 14 1005... 

H. Hoppe, M. Niggemann, C. Winder, J. Kraut, R. Hiesgen, A. Hinsch, D. Meissner, N. S. Sariciftci, Nanoscale Morphology of Conjugated Polymer/ Fullerene-Based Bulk-Heterojunction Solar Cells. Adv. Funct. Mater. 2004, 14, 1005-1011. 

Hoppe, H., N. Arnold, N.S. Sariciftci, and D. Meissner. 2003. Modeling the optical absorption within conjugated polymer/fullerene-based bulk-heterojunction organic solar cells. Sol Ener Mater Sol Cells 80 105. 

Hoppe, H., Niggemann, M., Winder, C., Kraut, J., Hiesgh, R., Hinsch, A., Meissner, D., Sariciftci, N.S. Nanoscale morphology of conjugated polymer/fullerene-based bulk-heterojunetion solar cells. Adv. Funct Mater. 14, 1005-1011 (2004)... 

It is the purpose of this chapter to introduce photoinduced charge transfer phenomena in bulk heterojunction composites, i.e., blends of conjugated polymers and fullerenes. Phenomena found in other organic solar cells such as pristine fullerene cells [11,12], dye sensitised liquid electrolyte [13] or solid state polymer electrolyte cells [14], pure dye cells [15,16] or small molecule cells [17], mostly based on heterojunctions between phthalocyanines and perylenes [18] or other bilayer systems will not be discussed here, but in the corresponding chapters of this book. 

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