Experimental and computational investigations of the photosensitive Schottky barrier diode property of an azobenzene based small organic molecule

Azo based organic semiconductor molecules are mostly used as write once, read-many-times (WORM) memory systems. Therefore, a large scope still remains in the fabrication of photoconducting azo compounds, which can be used under acute conditions for advanced applications. In this context we have designed a very simple, small azo based organic molecule, viz. [1,4-phenylenebis(azanylylidene)bis(methanylylidene)bis(2-methoxy-4-(phenyldiazenyl)phenol)] (compound 1). The device fabricated using compound 1 showed Schottky barrier behavior. The value of the rectification ratio is 6.22 and 18.27 under dark and photoirradiated conditions, respectively. Thermally stable and low cost compound 1 can be used in the area of optoelectronic devices probably being the first azo-organic material showing such properties. Experimentally measured optical conductivity is again correlated theoretically using DFT computation. It has been observed that the change in the dihedral angle produces a decrease in the energy for the allowed electronic transition.