Photoactive layers

Further research has taken the BHJ cells into more complex designs and new photoactive layers with values of energy conversion efficiencies from 0.13 [273] to 1.4% [282]. Graphene provides these cells with new characteristics impossible to match by ITO based cells, like functionality under extreme bending angles up to 138° under which ITO cells crack and fail after bending by 60° [221]. 

Photoactive Layered Materials Assembly of Ions, Molecules, Metal Complexes, and Proteins... 

Fig. 5.37. (a) I/V characteristics of typical MDMO-PPV/PCBM solar cells with a LiF/A1 electrode of various LiF thicknesses ( 3 A, 6 A, 12 A) compared to the performance of a MDMO-PPV/PCBM solar cell with a pristine A1 electrode ( ). (b) and (c) are box plots with the statistics of the FF and Voc from 6 separate solar cells. LiF or SiOx were thermally deposited at a rate of 1-2 A/min from a tungsten boat in a vacuum system with a base pressure of 10-4 Pa. We emphasize that, for thickness values of the order of 1 nm, LiF/SiOx does not form a continuous, fully covering layer, but instead consists of island clusters on the surface of the photoactive layer. Slow evaporation conditions are essential for more homogenous distribution of the LiF on the organic surface. The nominal thickness values given here represent an average value across the surface of the substrate. The metal electrode (either aluminum or gold) was thermally deposited with a thickness of 80 nm... 

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