Phthalocyanines photovoltaics

R. H. Tredgold, and R. Jones, Schottky-barrier diodes incorporating Langmuir-film interfacial monolayers, lEE Proc. 128 202 (1981). J.-P. Dodelet, H.-P. Pommier, and M. Ringuet, Characteristics and behavior of electrodeposited surfactant phthalocyanine photovoltaic cells, J. Appl. Phys. 53 4270 (1982). 

Several zinc(II) and aluminum(III) phthalocyanine derivatives substituted with carboxylic acid and sulfonic acid groups were anchored to nanocrystalline Ti02 films and tested for their photovoltaic behavior.72,73 Interestingly, zinc(II)-2,9,16,23-tetracarboxyphthalocyanine (55) exhibited 45% monochromatic current conversion efficiency at 700 nm. It is shown that electron injection to Ti02 occurs from the excited singlet state of the phthalocyanine derivatives. The... 

Figure 4.27 Phthalocyanine-perylene p-n junction photovoltaic cell.

Brumbach M, Placencia D, Armstrong NR (2008) Titanyl phthalocyanine/Cgo heterojunctions band-edge offsets and photovoltaic device performance. J Phys Chem C 112 3142... 

Placencia D, Wang WN, Shallcross RC, Nebesny KW, Brumbach M, Armstrong NR (2009) Organic photovoltaic cells based on solvent-annealed, textured titanyl phthalocyanine/Ceo heterojunctions. Adv Fund Mater 19 1913... 

The low stability of the magnesium porphyrins has precluded most potential applications. Other metallotetrapyrroles have found industrial uses for oil desulfurization, as photoconducting agents in photocopiers, deodorants, germicides, optical computer disks, semiconductor devices, photovoltaic cells, optical and electrochemical sensing, and molecular electronic materials. A few scattered examples of the use of Mg porphyrins in nonlinear optical studies have appeared" and magnesium phthalocyanines have been used in a few studies as semiconductor or photovoltaic materials" " One of the few... 

Solar energy conversion and photovoltaic devices encompass one of the most active applied topics of research in this area191. Thus, photoelectrochemical cells based on electrodes (Sn02, Pt) coated with tetrapyrroles have been studied for a long time191-194. Most studies were performed with phthalocyanines due to their stability and wide range of redox... 

Phthalocyanines possess intense absorption bands in the near-IR region and are known for their excellent stability, rendering them attractive for photovoltaic applications [62]. They have been repeatedly tested in the past as sensitizers of wide-band-gap oxide semiconductors and obtained poor incident photon-to-electric current conversion yields remaining under 1%, which is insufficient for... 

Zhu J, Shen Y, Gu F, Tao J, Zhang J (2007) Preparation and photovoltaic properties of near-infrared absorbing manganese(II) phthalocyanine polymer films. Mater Lett 61(6) 1296-1298... 

In addition to the complexation in solutions, pyridine-appended fulleropyrro-lidines can also form coordination complexes with zinc(II) phthalocyanines in solid-state thin films. Troshin et al. have investigated the photovoltaic behavior of bilayer solar cells fabricated by deposition of solution-processed fulleropy-rrolidines 36-40, which contain chelating pyridyl groups, on vacuum-evaporated films of unsubstituted zinc(II) phthalocyanine (ZnPc) [46], The UV-Vis spectra of these films resemble the spectrum of ZnPc recorded in pyridine, showing a sharp... 

A series of ruthenium(II) phthalocyanines with one or two pyridyl dendritic olig-othiophene axial substituent(s) have also been reported (compounds 50 and 51) [50], The dendritic ligands absorb in the region from 380 to 550 nm, which complements the absorptions of the phthalocyanine core. This combination results in better light harvesting property and enhancement in efficiency of the corresponding solar cells. The solution-processed photovoltaic devices made with these compounds and fullerene acceptor give efficiencies of up to 1.6%. These represent the most efficient phthalocyanine-based bulk heterojunction solar cells reported so far. 

Phthalocyanines are organic semiconductors that strongly absorb visible light, and have been extensively investigated for use in photovoltaic (11), and photoelectrochemical cells (12.). The results however were somewhat inconsistent, and this was probably due to the presence of impurities which were not always clearly identified. Commercially available phthalocyanine was analyzed in order to determine the trace elements present, as well as the effect of heat treatment on the iodine contamination. The X-ray spectra, for an accumulated charge of 15 (1C, from untreated and from H2PC purified for... 

Rectification and photovoltaic effects in organic p-n junctions were first reported by Kearns and Calvin [101] and by Meier [3]. The combination of rhodamines or triphenylmethane dyes (both n-type) with merocyanines or phthalocyanines (both p-type) generated photovoltages up to 200 mV and photocurrents of about 10 8 A at low light intensity, with power conversion efficiency much less than 1%. More recent studies have been performed on merocyanine and malachite green [89,90] and on phthalocyanines and TPyP (a porphyrin derivative) [102,103]. These devices showed stronger spectral sensitization and better spectral match to a solar spectrum than those of Schottky barrier cells using only one component. 

Physical incorporatiem of phthalocyanines and porphyrins in polymers was mentioned in Chap. 2.1.1 and 2.1.2. Moreover, photovoltaic properties of Schottky bavier solar cells were checked by dispersing metal free Pc in a polymer binder At peak solar power (135 mW/cm ) a power conversion efficiency of 1,2% has been obtained. 

The desirable properties of photovoltaic dyes have been reviewed, and porphyrins appear to be promising candidates. A model for the structure of zinc porphyrin deposited on to various metal oxides has been proposed and the use of zinc porphyrin-coated electrodes for the photo-oxidation of SO2 has been described. Further studies on carrier generation in 3-metal free phthalocyanine have been reported and a method for the deposition of Pt islands on X-phthalocyanine particles has been developed. The Pt-coated material is much more photoactive than naked phthalocyanine, and it catalyses oxidation of amines by O2. 

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