Poly fullerene blends

A bulk heteroj unction is by definition a blend of p-type and n-type semiconductors (donor/acceptor). As a prototype bulk heteroj unction, we shall discuss the properties of polymer/fullerene blends. Apart from the poly-... 

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... 

Erb T, Zhokhavets U, Hoppe H, Gobsch G, Al-lbrahim M, Ambacher O (2006) Absorption and crystallinity of poly(3-hex)dthiophene)/fullerene blends in dependence on annealing temperature. Thin Sohd Films 511-512 483... 

P. Boland, S. S. Sunkavalli, S. Chennuri, K. Foe, T. Abdel-Fattah, G. Namkoong, Investigation of Structural, Optical, and Electrical Properties of Regioregular Poly(3-Hexylthiophene)/Fullerene Blend Nanocomposites for Organic Solar Cells. Thin Solid Films 2010,518,1728-1731. 

A composition comprising a Ceo fullerene-terminated poly(A-[(propylphenyl]-AA, A -triphenyl-(l,l - biphenyl)-4,4 -diamine)methacrylate has been prepared by living radical polymerization. When blended with a plasticizer and a nonlinear chromophore, photorefractive efficiencies were improved by up to 9% at abiased voltage of 60 V/pm. 

The pure bulk-phase behavior was studied on blends consisting of poly(acryhc acidj/hydroxypropyl cellulose [44], poly(2-vinylpyridine)/end-sufonic acid poly(styrene) [45], and poly(acryHc acid)/poly(N,N-dimethyl-acrylamide) [46]. Goh et al. [47,48] and others [49] have studied an interesting example of [60]fullerenated poly(2-hydroxyethyl methacrylate) with poly(l-vinylimidazole) or poly(4-vinylpyridine) or poly(styrene-co-4-... 

Kim Y, Chouhs SA, Nelson J, Bradley DDC, Cook S, Durrant JR (2005) Device annealing effect in organic solar cells with blends of regioregular poly(3-hexjdthiophene) and soluble fullerene. Appl Phys Lett 86 063502... 

Blends of poly(ferrocenylmethylphenyisilane) (PFMPS) 48 and fullerenes as the active layers gave short circuit currents on the order of nanoamperes under white light illumination of ca. 160 mW cm" 2, with an open-circuit voltage from ca. 0.3 to 0.45 V [95]. Similar responses were obtained when the fullerenes were covalently attached to the polysilane backbone [96]. 

The miscibility of different Cgo-containing polystyrenes with other polymers was studied in attempts to transfer the fullerene properties to the resulting polymer blends [71]. It was found that poly(2,6-dimethyl-l,4-phenylene oxide), PPO, is miscible with all the PS/Cgo samples investigated, whereas in the case of poly (vinyl methyl ether), PVME, PS/Cgo samples were miscible only for lower contents of Cgo [71]. 

In typical work of Yu et al. [29], the arrays were fabricated on ITO glass substrates. The ITO glass layer was patterned by photolithography into perpendicular rows of electrode strips (width 450 pm, spacing 185 pm). The polymer film, a blend of poly(3-octyl thiophene) and fullerene PCBM[6,6] (see Section 6.3), was spin-cast onto the substrate. 

The hole mobility in such blends is observed to increase with increasing polymer content (as one would intuitively expect) and then peaks at a ratio of 6 4 (MEH-PPV [60]PCBM) before falling. A similar set of results has also been obtained using poly[2-methoxy-5-(3, 7 -dimethyloctyloxy-p-phenylene vinylene)] (MDMO-PPV) (see Figure S.lOd) [59]. Although not mentioned at the time, this observation has since been explained by the intercalation of fullerene molecules between the polymer side chains and a subsequent extension of the polymer backbone [84—86]. This can explain why the hole mobility of PPViPCBM blends increases with increasing fiiHerene content... 

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