Poly 2-methoxy-5- -1,4 phenylenevinylene

Fig. 7.17 The molecular structures of poly(p -phenylenevinylene), or PPV, (top), poly(2,5-diheptyl-p-phenylenevinylene), or DHPPV (middle) and poly(2-methoxy-S-(2 -ethyl-bexoxy)-p-phenylenevinylene), or MEHPPV (bottom).

The first realizations of polymer-polymer bulk heterojunction solar cells were independently reported in the mid-1990s by Yu and Heeger as well as by Halls et al. [28,30]. These solar cells were prepared from blends of two poly(para-phenylenevinylene) (PPV) derivatives the well-known MEH-PPV (poly[2-methoxy-5-(2 -ethylhexyloxy)-l,4-phenylenevinylene]) was used as donor component, while cyano-PPV (CN-PPV) served as acceptor component (identical to MEH-PPV with an additional cyano (- CN) substitution at the vinylene group). The blends showed increased photocurrent and power conversion efficiency (20-100 times) when compared to the respective single component solar cells. 

F. Motamedi, K. J. Ihn, Z. Ni, G. Srdanov, F. Wudl, and P, Smith, Fibers of poly(methoxy-2-ethyl-hex-yloxy)phenylenevinylene prepared from the soluble, fully converted polymer. Polymer 33 02 (1992). 

F Wudl and G Srdanov, Conducting Polymer Formed of Poly(2-Methoxy,5-(2 -Ethyl-Hexyloxy)-p-Phenylenevinylene), U.S. Patent 5,189,136, 1993. 

Examples of the optical pumping of solutions of luminescent conjugated polymers include laser action at 596 nm of poly[2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) using excitation with 6 ns Nd YAG third harmonic pulses (354.7 nm). ° Tuning of hexane solutions of the co-polymer poly(2,2, 5,5 -tetraoctyl-p-terphenyl-4,4 -xylene-vinylene-p-phenylenevinylene) (TOP-PPV) was possible between 414 and 456 mn, similar to the classical coumarin laser dyes. ... 

EDOT) coated CdSe nanorods as a function of the quantity of poly [2-methoxy-5-(3, 7 -dimethy locty loxy)-1,4-phenylenevinylene] (MDMO-PPV) added (solvent CHC13).151 (Reprinted with permission from D. Aldakov et al., Eur. Phys. J. Appl. Phys. 2006, 36, 261-265. Copyright the European Physical Journal.)... 

Figure 7.1 Chemical stractures of some common organic photovoltaic materials poly(2-methoxy-5-(3,7-dimethyloctyloxy)-l,4 phenylenevinylene) (MDMO-PPV), poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl Cei-butyric acid methyl ester (PCBM).

Pacios R., Chatten A. J., Kawano K., Durrant J. R., Bradley D. D. C. and Nelson J. (2006), Effects of photo-oxidation on the performance of poly 2-methoxy-5-(3, 7 -dimethyloctyloxy)-l,4-phenylenevinylene 6,6-phenyl Cei-butyric acid methyl ester solar cells , Adv. Eunct. Mat. 16, 2117-2126. 

Significant amount of research has been dedicated to two material systems MDMO-PPV PCBM (MDMO-PPV poly(2-methoxy-5-(3, 7 -dimethyl-octyloxy)-l,4-phenylenevinylene)) and RR-P3HT PCBM, which represent the state-of-the-art polymer solar cell technology. Because there are excellent review papers on the MDMO-PPV PCBM system in the literature, in this section we will only focus on the recent improvements in RR-P3HT PCBM system, especially the approaches to optimize the active blend layer for enhancing device efficiency. 

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