Electrical and optical properties of heterojunction formed by metal complexes of macrocyclic ligands

In this study, previously synthesized [Cu2(L5)(NO3)2][NO3]2, [Cu2(L2)(NO3)2][NO3]2,[Cu2(L7)(ClO4)2][ClO4]2, [Cu2(L8)(ClO4)2][ClO4]2 and [Cu2(L4)(ClO4)2][ClO4]2 organic Cu(II) complexes which have rich ? bonds and different ligands were used to examine the electrical and optical properties. The complexes were named as C1, C2, C3, C4 and C5, respectively. Thin films of Cu(II) complexes were formed by spin coating method on glass and n-Si substrates to investigate optical properties. Optical energy band gap (Eg) of thin films which formed on glass substrate weredetermined by measuring the UV-VIS absorption spectrometry. Optical parameters such as refractive index (n) and extinction coefficient (k) spectra of thin films on n-type Si substrate were determined by spectroscopic ellipsometry measurements. To investigate the electrical properties, thin films of thecomplexes were formed by spin coating on inorganic semiconductors. Thus organic-Inorganic (OI)structures were fabricated. Metal/Organic/Inorganic (Au/Cu(II) complex/n-Si) structure was created by evaporation of Au metal on organic/inorganic structure. For electrical characterization of Au /Cu(II) complex / n-Si structures current-voltage (I-V) measurements were taken at room temperaturein the dark conditions. Diode parameters such as ideality factor (n), barrier height ( ) and saturation current (I0) were determined and obtained parameters have been compared with Au/n-Si diode in the literature. Obtained results from I-V measurements have been also compared with results re-calculated by Cheung?s method. Capacity-voltage (C-V) measurements of all structures were taken at different frequency and room temperature. The results obtained from I-V measurements have been compared with those obtained from C-V measurements. Furthermore, photoelectrical characterization of metal/organic/semiconductor structures were investigated from I-V measurement under a solarsimulator with 100 mW/cm2light intensity and AM1.5 condition and their photovoltaic parameters such as short-circuit current (Isc) and open circuit voltage (Voc) were determined.Key Words: Cu (II) complex, Thin films, Schottky diode, Organic-inorganic heterojunction,Electrical properties, , Optical properties