AOMat 2016 Abstracts

Full Papers
Paper Nr: 2

Birefringence Creation by Solar Light - A New Approach to the Development of Solar Cells with Azobenzene Materials


Pedro Farinha, Susana Sério, Paulo A. Ribeiro and Maria Raposo

Abstract: 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.

Paper Nr: 5

High Perfomance Integrated Temperature Sensor based on Amorphous Silicon Diode for Photonics on CMOS


Sandro Rao, Giovanni Pangallo and Francesco Della Corte

Abstract: A temperature sensor based on a photonic layer-integrated hydrogenated amorphous silicon p-i-n diode is presented. The linear dependence of the voltage drop across the forward-biased diode on temperature, in a range from 30 °C up to 170 °C, has been used for thermal sensing. A high sensitivity of 11.9 mV/°C in a biasing current range ≈34-40 nA has been measured.

Short Papers
Paper Nr: 3

Preparation of PAH/Graphene Oxide Layer-by-Layer Films for Application on Solar Cells


I. C. C. Assunção, P. A. Ribeiro, Q. Ferreira, M. Raposo and S. Sério

Abstract: In this study we provide the preparation and characterization of layer-by-layer LBL films made with poly(allylamine hydrochloride) (PAH) alternated with graphene oxide. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed a smooth surface with a RMS roughness of 5.74 nm. The LBL films were also characterized by means of UV-vis spectroscopy. The I-V characteristic curve evidenced a typical semiconductor behaviour.

Paper Nr: 4

Methylene Blue - A Trendy Photosensitizer in Medicine and in Solar-Energy Conversion Systems


Filipa Pires, Margarida Coelho, Paulo A. Ribeiro and Maria Raposo

Abstract: The photosensitizer methylene blue (MB) has been investigated as a deoxyribonucleic acid (DNA) intercalant with the main objective of understanding the chemical/physical processes, which occur when adequate wavelength light is impinging on DNA intercalated with MB. This understanding is crucial for the creation of dynamic phototherapy procedures and for the development of new dye sensitized solar cells. During this work we developed and optimized all the conditions to efficiently produce [MB/DNA] multi-layered films by self-assembly. Our study revealed that pH strongly influences the growth of our multilayer films. Our UV studies revealed that the UV radiation causes damage of DNA through opening of aromatic ring and by breaking the DNA phosphate groups. The FT-IR studies on cast films with [MB/DNA] revealed that the denaturation ratio decreases as the irradiation increases, meaning that MB is an intercalant of DNA chain. This study paves the way to develop new dye sensitized solar cells which employ inexpensive materials and take advantage of the intercalation process in order to adjust the intermolecular arrangement of the donor/acceptor molecules to improve the performance of the device.