MDMO current-voltage characteristic

Fig. 22 Optical transmission spectra of 100-nm-thick MDMO-PPV PCBM (1 4 by wt.) films spin cast onto glass substrates from either toluene (dashed line) or chlorobenzene (solid line) solutions (a). Incident photon to collected electron (IPCE) spectra (b) and current-voltage characteristics (c) for photovoltaic devices using these films as the active layer. (Reprinted with permission from [34], 2001, American Institute of Physics)...

Fig. 30 Photovoltaic properties of an MDMO-PPV based polymer-fullerene solar cell with an active area of 0.1 cm. a External quantum efficiency (EQE) of [70]PCBM MDMO-PPV cells, spin-coated from chlorobenzene (triangles) and ODCB (squares) and of [60]PCBM MDMO-PPV devices spin-coated from chlorobenzene (open circles) b current-voltage characteristics of [70]PCBM MDMO-PPV devices, spin-coated from ODCB in the dark (open circles) and under illumination (AM 1.5, 1000 W/m squares). The inset shows the I-V characteristics in a semilogarithmic plot. (Reproduced with permission from [170], 2003, Wiley-VCH)...

CdSe nanocrystal based solar cells were substantially improved by Sun et al a twofold increase in the EQE was achieved for MDMO-PPV based blends by application of CdSe nanotetrapods instead of nanorods [254]. The tetrapods, due to their shape, induced better directed electron transport normal to the film plane, yielding overall power conversion efficiencies of 1.8%. The current-voltage characteristics of this device are displayed in Pig. 57. 

Fig. 5.21. Top figure The experimental plots of dark and illuminated J—V characteristics of a typical MDMO-PPV/PCBM solar cell for different concentrations of PCBM. The currents are plotted on the log scale. Curves 1 are for dark currents and curves 2 are for illuminated currents. The open circles show the dark currents needed to make the output current zero at the open circuit voltage. Bottom figure The current densities are plotted on the linear scale for two PCBM concentrations. Curves 1 are for dark currents and curves 2 are for illuminated currents.

Brabec and coworkers have made extensive measurements of the dark and illuminated currents of MDMO-PPV/PCBM BHSCs [124,141], The experimental results for the BH-SCs from their paper [124] are shown in Fig. 5.22. There are points of inflexion in the dark current of the organic solar cell confirming that the dark current is the space charge limited currents. These features, particularly the points of inflexion, are absent in the illuminated characteristics. At larger voltages the forward dark current intersects the illuminated current and the illuminated current becomes larger than the dark current. 

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