Photoelectrochemical Cell with Dye Molecules Oriented in Nematic Liquid Crystal

Abstract

A photoelectrochemical cell consisting of two semiconducting electrodes covered by orienting SiO x layers and filled with merocyanine solutions in nematic liquid crystal was constructed. Dye molecules were oriented as a result of the guest-host effect. Generation of photocurrent by two components of polarized light gives different values of photocurrent"ampalitude but anisotropy of photocurrent is lower than that of absorption in the region of a free base form of dye. It is explained by dominant participation of a protonated form of dye in the photocurrent generation. The 1ast form exhibits a lower degree of orientation than the free base form of dye.

Spectroscopic and photoelectric studies of phthalocyanines in polyvinyl alcohol for application in solar energy conversion

“…The comparison of I(V) characteristics shown in Figure 7 and of the parameters presented in Table 2 with those obtained for porphyrins in nematic liquid crystal [9] leads us to the conclusion that the effectiveness of current generation in the electrochemical cell with porphyrin/phthalocyanine is enhanced when dyes are dissolved in liquid polymer matrix instead of in nematic liquid crystal (LC) as we observed in paper [10]. The alternation in shape of I(V) characteristics in PVA/DMSO (this paper) and in LC [10,35] can be explained by the difference in electric properties of the used electrolyte.…”

“…In the light of all our investigations done for a number of metallic, metal-free and substituted porphyrins [10,33] we could indicate that porphyrin complexed with Mg or Zn showed the highest effectiveness in photocurrent generation. The same trend is also observed in this paper when phthalocyanine was complexed with Mg. Another feature which markedly differs MgPc from other investigated Pcs is its very good solubility in PVA/DMSO As shown, the characteristics of the electrochemical cell fulfilled with dye-PVA/DMSO (this paper) and with dyeliquid crystal (LC) solutions [9,10] differ from each other and indicate that polymer matrices can influence the MgPc photocurrent generation by changing the internal electric fields most probably due to enhance the charge carrier dissociation [10,35]. Such an observation has also been done for ZnPc in polycarbonate [29].…”

Interactions between photosynthetic pigments in organisms and in model systems

“…Therefore, we have to learn from Nature how to construct a perfect system for hydrogen production (Tien and Karvaly 1977) or how to construct systems for the conversion of photon energy into electrical energy (Ptak et al 1997a). Such systems can be constructed on the basis of some parts of photosynthetic organisms (Frąckowiak andNaser 1997, Naser et al 1997) or from non-biological materials but using knowledge of the mechanisms of energy conversion elaborated by Nature during millions of years of evolution.…”