Investigation of optical band gap and device parameters of rubrene thin film prepared using spin coating technique

• Published in: Journal of alloys and compounds 2014-01, Vol.582, p.696-702
• Main Authors: Tuğluoğlu, Nihat, Barış, Behzad, Gürel, Hatice, Karadeniz, Serdar, Yüksel, Ömer Faruk
• Format: Article
• Language: English
• Subjects: Absorption coefficient; Barriers; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Device parameters; Devices; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Ohmic; Optical band gap; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics; Rubrene organic compound; Spectra; Spin coating; Spin coating technique; Surface double layers, schottky barriers, and work functions; Thin films; Volt-ampere characteristics
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2013.08.067

•Thin film of rubrene has been deposited by spin coating technique.•The band gap properties of the film were investigated in the range 200–700nm.•The analysis of the absorption coefficient revealed indirect allowed transition.•The parameters such as barrier height and ideality factor were determined. Rubrene thin film has been deposited by spin coating technique. The optical band gap properties of rubrene thin film have been investigated in the spectral range 200–700nm. The results of the absorption coefficient (α) were analyzed in order to determine the optical band gap and Urbach energy of the film. The absorption spectra recorded in the UV–vis region shows two peaks at 250nm and 300nm. The analysis of the spectral behavior of the absorption coefficient (α) in the absorption region revealed indirect allowed transition with corresponding energy 2.31eV. The value of Urbach energy (EU) was determined to be 1.169eV. The current–voltage (I–V) characteristics and electrical conduction properties of rubrene/n-Si device fabricated by spin coating method have also been investigated. The I–V characteristic in dark was showed the rectification effect due to the formation of Schottky barrier at rubrene/silicon interface. From analyzing the I-V measurement for the device, the basic device parameters such as barrier height, ideality factor and series resistance were determined. At the low-voltage region, the current conduction in Au/rubrene/n-Si device is ohmic type. The charge transport phenomenon appears to be space charge limited current (SCLC) at higher-voltage regions.