New Indolo[3,2-b]indole based small organic molecules for Organic Thin Film Transistors (OTFTs): A combined experimental and DFT Study

Synthesis of new indolo[3,2-b]indoles (5a- 5j) in presence of Ag-doped ZnO and (Diacetoxyiodo) benzene system under visible-light have been reported. All the new fused linear heterocyclic indolo[3,2-b]indole systems (5a- 5j) thoroughly characterized by spectroscopic methods like mass, UV-visible, NMR and C, H, N elemental analysis. Further, their photophysical properties were carried out by combined experimental and theoretical studies. Thermogravimetric studies are carried out to confirm the thermal stability of molecules. The frontier molecular orbitals of molecules are characterized with the help of cyclic voltammetry. Additionally, the compounds of series 5 were used for the fabrication of organic thin-film transistors, which indicated the hole mobilities in the range of 0.11 – 0.85 cm2/Vs and with on/off ratio 105 on ODTS-SiO2 substrate at 50 °C and are also supported by DFT studies.