Power conversion, conjugated polymers

Comparison of the spectral response and of the power efficiency of these first conjugated polymer/fullerene bilayer devices with single layer pure conjugated polymer devices showed that the large potential of the photoinduced charge transfer of a donor-acceptor system was not fully exploited in the bilayers. The devices still suffer from antibatic behavior as well as from a low power conversion efficiency. However, the diode behavior, i.e. the rectification of these devices, was excellent. 

The excellent photosensitivity and relatively high energy conversion efficiencies obtained from the bulk hetcrojunction materials arc promising. The monochromatic power efficiencies for conjugated polymer photovoltaic devices are around... 

Besides ruthenium complexes, rhenium complexes were also used as the photosensitizers in photovoltaic cells. Bulk heterojunction photovoltaic cells fabricated from sublimable rhenium complexes exhibited a power conversion efficiency of 1.7%.75,76 The same rhenium complex moiety was incorporated into conjugated polymer chains such as polymer 16a c (Scheme 9). Fabrication of devices based on conjugated rhenium containing polymers 17a c and SPAN by the LbL deposition method was reported.77 The efficiencies of the devices are on the order of 10 4%. 

However, in order to make progress toward 10% power conversion efficiency [102] further efforts need to be applied. One very promising concept is synthesizing low band gap conjugated polymers for solar energy conversion [198,199]. Thereby a factor of 2 is expected on the photocurrent, if... 

Several device concepts employing conjugated polymers as active components in the photoconversion process of photovoltaic devices have been presented to date. With power conversion efficiencies surpassing 5% (polymer-fullerene), reaching 3% (hybrid polymer-nanoparticle), or 2% (polymer-polymer), the prospects are high. 

Finally, conjugated materials 40 based on poly(phenylene thiophene) and poly (fluorene thiophene) main chain polymers functionalized with pendant trithiocyanato ruthenium terpyridine complexes were synthesized by the Suzuki coupling reaction. Heterojunction photovoltaic cells with the simple structure ITO/polymer/C-60/Al were fabricated. Under simulated AM1.5 solar light illumination, the short circuit currents, open circuit voltages, and power conversion efficiencies of the photovoltaic cells were measured to be 1.53-2.58 mAcm 2, 0.12-0.24 V, and 0.084-0.12%, respectively [77]. 

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