Using green chemistry routes to fabricate green n-type organic semiconductors for the transistor construction

Title : Using green chemistry routes to fabricate green n-type organic semiconductors for the transistor construction

Abstract:

Traditionally, Organic Thin Film Transistors (OTFT) possess p-type Semiconductors made by pentacene or tetracene, usual organic materials in electronics with toxic precursors for manufacturers and environment. Much later, the organic n-type semiconductors were applied in organic transistor fabrication: fullerene C60, dioctyl-perylene tetra-carboxylic diimide (PTCDI-C8H17) or hexa-deca-fluoro-copper-phthalocyanine (F16CuPc) and the list continues with multiple compounds based on Polycyclic Aromatic Hydrocarbons (PAH) [1]. Even pentacene combined with special metals used for source and drain contacts, in special environmental conditions, is used for n-type OTFT [2].

Our group reported the fabrication of an n-type semiconductor, with very low toxicity for organic transistors, using sulpho-salicylic acid (SSA) grafted on ferrite core-shell (Fe₃O₄-SSA), appealing to the green synthesis routes, [3].

The toxicity of the PAH compounds is indicated by their lethal dose LD50 between 14 mg/kg to 90 mg/kg, [4]. The extracted lethal dose within a mices sample was established to 700 mg/kg, for SSA, [5]. This value indicates much lower toxicity of SSA than that of PAH.

The n-type character of the Fe₃O₄-SSA compound, as donor of electron, was demonstrated by 2 methods: (i) by simulations with Hyperchem molecular modeling program, indicating the normalized values at the elementary electric charge. We observed that sulphonate group, SO₃H, possesses net negative electronic charge density of -0.298, so it is negative. (ii) by construction of an OTFT, based on Fe₃O₄-SSA semiconductor and monitoring its main device parameters: threshold voltage V_T = +5 V, conduction current I_ON = 16 nA and ratio I_ON/I_OFF = 500. The measured parameters, especially the threshold voltage takes a positive value to trigger the electrons accumulation current, demonstrating an n-type OTFT with accumulation channel, rich in electrons, at positive gate voltage.

Biography:

Prof. C. Ravariu studied Microelectronics at the Polytechnic University of Bucharest, Romania. He worked as scientific researcher first 5 years at Institute of Microtechnology, Bucharest, then joined the Polytechnic University of Bucharest. Since 2013 he obtained the position of Full Professor at the Polytechnic University of Bucharest, Faculty of Electronics, Romania. He has published more than 250 research articles. Since 2014 he is Chairman of the Romanian IEEE Electron Devices Chapter and his main interest is in nano-bio-devices, organic semiconductors for electronic devices and biomedical research