Bulk heterojunction cells

Photovoltaic Devices with OPV4—Ceo- The increased lifetime of the charge-separated state, which extends into the millisecond time domain, opens the possibility of using the OPVrt-Coo dyads as the active material in a photovoltaic device. As an important difference with previous bulk heterojunction cells, the covalent linkage between donor and acceptor in these molecular dyads restricts the dimensions of the phase separation between the oligomer and the fullerene that could freely occur in blends of the individual components. This can be considered as a primitive attempt to obtain more ordered and better-defined phase-separated D-A networks. 

Figure 1.5 Typical organic photovoltaic cell architectures, (a) Bilayer cell (b) bulk heterojunction cell.

Dye-Sensitized Cells Dye-sensitized solar cells (DSSCs) are slightly more complex than bilayer and bulk heterojunction cells, but as was the case for bilayer cells, the increase in device complexity reduces the number of functions that must be performed by each of the materials. A schematic drawing of a dye-sensitized solar cell is shown in Fig. 8.8. A layer of sintered, interconnected TiC>2 nanoparticles, which serves as the electron transport material (ETM), is coated by a thin layer of light absorbing dye. The remaining pores in the dye-coated TiC>2 layer are then filled with a... 

Dye-sensitized solar cells (DSCs) are a paricularty successful example of a bulk heterojunction cell architecture. A wide bandgap inorganic semiconductor (typically a metal oxide) is sensitized to the solar spectrum by attaching a surface-adsorbed... 

Peumans, P. Uchida, S. Forrest, S. R. 2003. Efficient bulk heterojunction photovoltaic cells using small-molecular-weight organic thin films. Nature 425 158-162. 

Dennler, G. Scharber, M. C. Brabec, C. ]., Polymer-fullerene bulk-heterojunction solar cells. Adv. Mater. 2009, 21,1323-1338. 

Fig. 3 Contemporary organic solar cell devices are based on donor/acceptor heterojunction device architectures, (a) Energy level diagram, (b) Planar heterojunction conligmation. (c) Bulk heterojunction configuration...

Liang YY, Xu Z, Xia JB, Tsai ST, Wu Y, Li G, Ray C, Yu LP (2010) For the bright future-bulk heterojunction polymer solar cells with power conversion efficiency of 7.4%. Adv Mater 22 E135... 

Howard lA, Laquai F (2010) Optical probes of charge generation and recombination in bulk heterojunction organic solar cells. Macromol Chem Phys 211 2063... 

Blom PWM, Mihailetchi VD, Koster LJA, Markov DE (2007) Device physics of polymer fullerene bulk heterojunction solar cells. Adv Mater 19 1551 Onsager L (1938) Initial recombination of ions. Phys Rev 54 554... 

Limpinsel M, Wagenpfahl A, Mingebach M, Deibel C, Dyakonov V (2010) Photocurrent in bulk heterojunction solar cells. Phys Rev B 81 085203... 

Pal SK, Kesti T, Maiti M, Zhang EL, Inganas O, Hellstrom S, Andersson MR, Oswald F, Langa F, Osterman T, Pascher T, Yartsev A, Sundstrom V (2010) Gemmate charge recombination in polymer/fullerene bulk heterojunction films and implications for solar cell function. J Am Chem Soc 132 12440... 

Scharber MC, Wuhlbacher D, Koppe M, Denk P, Waldauf C, Heeger AJ, Brabec CL (2006) Design rules for donors in bulk-heterojunction solar cells - towards 10% energy-conversion efficiency. Adv Mater 18 789... 

One of the most promising uses of C60 involves its potential application, when mixed with 7r-conjligated polymers, in polymer solar cells. Most often the so-called bulk heterojunction configuration is used, in which the active layer consists of a blend of electron-donating materials, for example, p-type conjugated polymers, and an electron-accepting material (n-type), such as (6,6)-phenyl-Cgi -butyric acid methyl ester (PCBM, Scheme 9.6).38... 

FIGURE 2. Device configuration for heterojunction (a) and bulk-heterojunction (b) organic thin film solar cells. 

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