Birefringence creation by solar light: A new approach to the development of solar cells with azobenzene materials

The conversion of solar energy into electricity is one of the viable alternatives regarding energy demand and sustainability. This work shows that novel energy storage devices can be developed by using materials containing highly polarizable molecules as poly{1-(4-(3-carboxy-4-hydroxy-phenylazo) benzenesulfonamido) −1,2-ethanediyl, sodium salt} (PAZO). In the present case, layer-by-layer (LbL) of PAZO and poly(allylamine hydrochloride) (PAH) thin films were prepared and the creation and relaxation of photoinduced birefringence were characterized. These results demonstrate that birefringence can be induced in these films by visible light with a spectrum similar to solar light. Comparing the characteristics parameters of birefringence creation and relaxation, it was seen that the writing birefringence characteristic time, with a value of 1.4 hours, is quite slower than the obtained with laser beam but the relaxation characteristic time is of the order of 7 days. In addition, the birefringence value is proportional to the amount of azo-groups in the sample. These preliminary results allows us conclude that solar devices based in that principle can be studied, namely, the conversion of the oriented dipoles stored energy in power.