Bulk heterojunction diodes

Fig. 5.7. Typical I/V characteristics of a bulk heterojunction diode. The schematic band diagrams for the three different diode regimes axe depicted in the figure according to the applied voltage...

The hole mobility /u-h in OCiCio-PPV is 5 x 10-11 m2/V s. The electron mobility /xe in PCBM is 2 x 10-7 m2/V s. However, the transport of separate charge carriers in an interpenetrating network may be different than the transport in the individual compounds. In Ref. [65] the transport and injection of charge carriers in OCiCio-PPV PCBM bulk-heterojunction diodes are investigated. 

Fig. 5.18. Measurement and simulation of a bulk heterojunction solar cell in the dark (a) and under illumination (b). The dark I/V characteristics are plotted semi-logarithmically, whilst the illuminated characteristics are plotted on a linear scale. The bulk heterojunction was simulated as a diode with the following structure positive electrode/p++/i/n++/negative electrode, (c) Local variation of the energy levels (top) and of the carrier densities for a bulk heterojunction solar cell with balanced mobilities, (d) Local variation of the energy levels (top) and of the carrier densities for a bulk heterojunction solar cell with higher electron mobility...

Table 5.3. Solar cell characteristics (PF and Voc) of MDMO-PPV/PCBM bulk heterojunction devices for various interfacial layers (LiF, SiO ) with different thicknesses compared to a solar cell with a pristine A1 electrode, and also calculated diode characteristics Rs and Rp found using (5.39) for the various interfacial layers...

The observed experimental result that Voc decreases linearly for bulk heterojunction solar cells allows us to conclude that, at least in the high temperature range (T > 200 K), these solar cells may be described by a diode model with Ip exp(E/kT). Here E is a parameter analogous to Eg for conventional semiconductors. For conjugated polymer/fullerene bulk heterojunction solar cells, E should correspond to the energy difference between the HOMO level of the donor and the LUMO level of the acceptor components of the active layer [as also suggested by the extrapolated value of V oc(0 K)]. 

Magnetoresistance in Poly (3-hexyl thiophene) Based Diodes and Bulk Heterojunction Solar Cells... 

Fig. 3. %MR as a function of magnetic field for a typical RRP3HT based diode and a P3HT PCBM bulk heterojunction solar cell at room temperature showing almost negligible MR of good solar cells compared to the diodes.

Device Models of Bulk Heterojunction Solar Cells. 10-27 The Equivalent Circuit Model Extended One-Diode Model Electric Field-Dependent Dissociation of the Coulomb-Coupled E-H Pairs Numerical Solution to the Drift-Diffusion Equations... 

FIGURE 10.21 Current density-voltage curves of bulk heterojunction solar cells under 80 mW cm stimulated AM 1.5 illumination. The inset shows the replacement circuit of a one-diode model. 

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