Phenyl-C61-butyric acid methyl ester PCBM

In a bulk-heterojunction photovoltaic cell with methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) as an electron acceptor, alternating copolymer 19 (Fig. 9), derived from 2,7-fluorene and 2,5-dithienylsilole, can show impressive performance as the electron donor.31 In a device configuration of ITO/PEDOT/active layer/Ba/Al, the dark current density—bias curve shows a small leakage current, suggesting a continuous, pinhole-free active layer in the device. Under illumination of an AM 1.5 solar simulator at 100 mW/cm2, a high short-circuit current of 5.4 mA/cm2, an open-circuit voltage of 0.7 V, and a fill factor of 31.5% are achieved. The calculated energy conversion efficiency is 2.01%. 

Nowadays the best performing organic photovoltaic cell is represented by a bulk heterojunction (BHJ) solar cell based on the polymer poly(3-hexylthiophene) (P3HT) and the fullerene derivative [6, 6]-phenyl-C61-butyric acid methyl ester (PCBM), with reproducible efficiencies approaching 5% [262,263], However, a serious drawback for the preparation of efficient organic photovoltaic cells is represented by the low optical absorbance in the red/near-infrared region of the lightharvesting component(s), as well as their low extinction coefflcient(s). 

Mihailetchi [134] investigated the open circuit voltage of the bulk heterojunction organic solar cells based on methanol-fullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) as electron acceptor and poly[2-methoxy-5(3 ,7 -dimethyloctyloxy)-p-phenylene vinylene] (OC1C10-PPV) as an electron donor. It is known that a single layer device follows the MIM model [166] and the open circuit voltage V0c is equal to the difference in the work functions of the metal electrodes [134], If charges accumulate in the... 

Figure 3.17 Poly(N-vinyl pyrrolidone] (PVP] and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM] structures.

FIGURE 8.1 Chemical structure of (a) polystyrene (PS), (b) poly(methyl methacrylate) (PMMA), (c) 8-hydroxyqui-noline (8HQ), (d) 1-dodecanethiol (DT), (e) 2-naphthalenethiol (2NT), (f) polyaniline (PANI), (g) tetrathiafiilvalene (TTF), and (h) methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM). 

Regioregular PHT, a p-type conjugated polymer, blended with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), as n-type material, is an active material for photovoltaic devices (40). The deposition methods and the induced morphology strongly influence the functionality of the active material and in turn the final charge generation performances of a photoactive layer. 

Scharber et al. have proposed a relation between the HOMO of the polymer and the open circuit voltage Foo which was used to estimate the maximum efficiency of bulk-heterojunction solar cells for a number of material combinations, including P3HT and phenyl-C61-butyric acid methyl ester (PCBM) [36]. As an alternative to energy level determination with electrochemistry, the method of photoelectron spectroscopy can be used Kahn and coworkers used a combination of direct and inverse photoemission spectroscopy complemented by near edge X-ray absorption fine structure (NEXAFS) for determination of the HOMO and LUMO energy levels and the energy gap between the LUMO of the acceptor and the HOMO of the donor [37]. 

The PCE is commonly obtained by measuring the current density (/) versus the applied potential (U) for aPV device under AM1.5G illumination. Figure 2c shows a typical JIV curve for an OPV device based on the donor P3HT and the acceptor phenyl-C61-butyric acid methyl ester (PCBM). The current density measured at zero applied potential is the short-circuit current density (/sc)- The applied voltage necessary to drive the current to zero is the open-circuit voltage (Voc)- The PCE is determined by calculating the maximum power produced, which is the maximum product of / X F and is denoted by / 3tid Umax-... 

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