Morphological, structural and electrical properties of pentacene thin films grown via thermal evaporation technique

Abstract

The physical and structural characteristics of pentacene thin films on indium tin oxide (ITO)-coated glass were studied. The pentacene films were deposited using the thermal evaporation method with deposition times of 20, 30, and 60 minutes. Field-emission scanning electron microscopy (FESEM) images revealed that film thickness increased with deposition time, with a bulk phase layer appearing at 60 minutes. The presence of the thin-film phase corresponding to 15.5 Å lattice spacing was demonstrated by X-ray diffraction (XRD) patterns in pentacene films with deposition times of 20 and 30 minutes. Meanwhile, with a deposition time of 60 minutes and a lattice spacing of 14.5 Å, the existence of the bulk phase was verified in the pentacene film. Atomic force microscopy (AFM) images of the crystallinity of the pentacene films revealed that the pentacene films deposited on ITO-coated glass exhibited the formation of similar islands with modular grains, results in a fine crystalline structure. From the current-voltage (I-V) and current density-voltage (J-V) characteristics, the pentacene films were ohmic and that current increased as the pentacene’s thickness decreased. Pentacene films deposited on an ITO-coated glass substrate showed potential in the development of broadband and narrowband optoelectronic devices on a transparent substrate.

Post-Growth Dynamics and Growth Modeling of Organic Semiconductor Thin Films

“…Organic electronics typically relies on thin films used as active layers in devices, , whose performances are found to be highly dependent on the film structure and morphology, directly dictating the optoelectronic properties. , For a successful integration in devices, control over the film growth is, therefore, crucial . One of the best techniques to obtain thin films with high control on structure and morphology is organic molecular beam epitaxy (OMBE), which allows fine-tuning of the growth parameters. − Nonetheless, even films grown via OMBE may experience a post-growth evolution in a controlled environment and/or in ambient conditions, through different processes such as wetting, dewetting, or ripening, − often characterized by a change in the morphology and/or structure, − which may affect device performance and long-term stability.…”

“…1 Organic electronics typically relies on thin films used as active layers in devices, 2,3 whose performances are found to be highly dependent on the film structure and morphology, directly dictating the optoelectronic properties. 4,5 For a successful integration in devices, control over the film growth is, therefore, crucial. 6 One of the best techniques to obtain thin films with high control on structure and morphology is organic molecular beam epitaxy (OMBE), which allows fine-tuning of the growth parameters.…”