ABSTRACT
In this work, it is proposed the development of organic semiconductors (OS) based on uranyl(VI) complexes. The above by means of the synthesis and the characterization of the complexes by Infrared spectroscopy, Nuclear magnetic resonance spectroscopy, mass spectrometry, and X-ray diffraction. Films of these complexes were deposited and subsequently, topographic and structural characterization was carried out by Scanning Electron Microscopy, X-ray diffraction, and Atomic Force Microscopy. Additionally, the nanomechanical evaluation was performed to know the stiffness of uranyl films using their modulus of elasticity. Also, the optical characterization took place in the devices and their bandgap value ranges between 2.40 and 2.93â eV being the minor for the film of the uranyl complex with the N on pyridine in position 4 (2 c). Finally, the electrical behavior of the uranyl(VI) films was evaluated, and important differences were obtained: the uranyl complex with the N on pyridine in position 2 (2 a) film is not influenced by changes in lighting and its current density is in the order of 10-3â A/cm2. The film with uranyl complex with the N on pyridine in position 3 (2 b) and 2 c presents a greater current flow under lighting conditions and two orders of magnitude larger than in film 2 a. In these films 2 b and 2 c, ohmic behavior occurs at low voltages, while at high voltages the charge transport changes to space-charge limited current behavior.
ABSTRACT
The hybrid film of molybdenum oxide (MoO3) and poly(3,4-ethylenedyoxithiophene) polystyrene sulfonate (PEDOT:PSS) is a promising candidate for use as hole transport layer (HTL) in low-cost devices. A fast, controllable and economic process was used to fabricate high-performance HTLs by adding organotin (IV) semiconductors to the MoO3/PEDOT:PSS films. These hybrid films were fabricated by spin-coating and the MoO3/PEDOT:PSS-organotin (IV) complex films were characterized by infrared spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Some mechanical and optical properties of the hybrid films were obtained and, to electrically characterize the hybrid films, hetero-junction glass/ITO/MoO3/PEDOT:PSS-organotin (IV) complex/Ag devices were prepared. Regarding the mechanical properties, the films have high plastic deformation, with a maximum stress of around 40 MPa and a Knoop hardness of 0.14. With respect to optical behavior, the films showed high transparency, with optical gap values between 2.8 and 3.5 eV and an onset gap of around 2.4 eV, typical of semiconductors. Additionally, the films in their respective devices show ambipolar and ohmic behavior with small differences depending on the substituent in organotin (IV) semiconductors. The MoO3/PEDOT:PSS matrix defines the mechanical behavior of the films and the tin complexes contribute their optoelectronic properties.
