Bulk heterojunction architecture

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...

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

Fig. 12 Examples of device architectures of conjugated polymer-based photovoltaic cells a single layer b bilayer c disordered bulk heterojunction d ordered bulk heterojunction. (Reproduced with permission from [71], 2005, American Chemical Society)...

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... 

Rathgeber S, Perlich J, KAhnlenz F, TArk S, Egbe DA, Hoppe H, et al. Correlation between polymer architecture, mesoscale structure and photovoltaic performance in side-chain-modified poly(p-arylene-ethynyl-ene)-alt-poly(p-arylene-vinylene) PCBM bulk-heterojunction solar cells. Polymer 2011 52(17) 3819-26. 

To ensure that all photogenerated excitons reach a donor-acceptor interface, the heterojunction formed between the two materials has to be scaled down to the nanometer level to form an architecture that is referred to as bulk heterojunction [42]. As such, the bulk heterojunction can be regarded as an ensemble of nanoscale heterojunctions distributed all over the volume forming a bicontinous network. 

Figure 6.1 Four device architectures of conjugated polymer-based photovoltaic cells (a) single-layer polymer PV cell (b) bilayer polymer PV cell (c) disordered bulk heterojunction (d) ordered...

Fullerene/polymer organic bulk heterojunction solar cells have very simple architecture (Figure 47a). To make such devices, fullerene derivative and a conjugated polymer are dissolved together in an appropriate solvent. The resulting solution is deposited on a conducting substrate... 

In 1995, Heeger and eo vorkers introduced the bulk-heterojunction (BHJ) structure by simply blending polymer and fullerene as active materials, whieh is considered the best PSC device architecture. The extensive studies of donor polymer photovoltaic materials have been well discussed and reviewed.Although thousands of donor polymers with different backbones and side groups have been developed, synthesized and applied in PSCs, donor polymers ean be roughly classified into two types according to their struetures, namely the elassical and novel donor polymers. 

Figure 4.1 (a) Device architecture of inverted bulk heterojunction polymer solar... 

Figure 5.1 (Left) Standard device architecture. The active layer is composed of a bulk-heterojunction (BHJ) network. (Right) Simplified view of the device operation for an organic solar cell.

The principles of OSCs have been outlined in detail elsewhere. Various types of cell architectures have been proposed of which three are of main interest (1) bulk heterojunction solar cells in which electron donors and acceptor are homogeneously mixed to jointly form a functional layer, for example, poly(3-hexylthiophene) (P3HT) as the donor and substituted fullerenes like [6,6]-phe-nyl-C61-butyric acid methylester (PCBM) as the acceptor (2) multilayer devices of vacuum-deposited small molecules and (3) dye-sensitized nanostructured oxide cells, for example, dyes attached to the surface of nano-Ti02. 

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