Deposition and Characterization of Heterostructures Based on Doped Ferrocene for Film-Device Applications

Abstract
Novel heterostructures based on ferrocenium hexafluorophosphate (FcPF6), 2,6-dihydroxyanthraquinone (DHAQ) or 2,6-diaminoanthraquinone (DAAQ), zinc phthalocyanine (ZnPc) and nylon 11 were deposited by the high-vacuum thermal evaporation (HVTE) technique. Morphological and mechanical characterizations of these organic heterostructures FcPF6:DHAQ/nylon(ZnPc) and FcPF6:DAAQ/nylon(ZnPc) were carried out. Subsequently, corresponding optical parameters were calculated. The heterostructure with FcPF6:DHAQ presented the lowest optical band gap and fundamental band gap at 1.55 eV and 2.45 eV, respectively. The nylon(ZnPc) layer favors the optical behavior and places these heterostructures within organic low-bandgap semiconductor range. Additionally, devices were fabricated, and their electrical behavior was evaluated. The ITO/FcPF6:DHAQ/nylon(ZnPc)/Ag device exhibits ohmic behavior, and the ITO/FcPF6:DAAQ/nylon(ZnPc)/Ag device exhibits ohmic behavior at low voltages, but at V ≥ 5 V, its behavior changes to Space Charge Limited Current (SCLC). This device carries a maximum current of 0.02 A, three orders of magnitude higher than the current carried by the device with the DHAQ. The SCLC conduction mechanism showed a hole mobility of 9.27 × 10−8 (cm2)/Vs, the concentration of thermally excited holes of 3.01 × 1023 m−3, and trap concentration of 3.93 × 1021 m−3. FcPF6:DHAQ/nylon(ZnPc) and FcPF6:DAAQ/nylon(ZnPc) are potential candidates for organic devices as an emitter layer and active layer, respectively.