Synthesis and characterization of organotin(IV) semiconductors and their applications in optoelectronics
A new series of organotin(IV) semiconductors derived from aryl hydroxymethylidene indanones has been synthesized and characterized. The products have been examined as hole-injection layers (HILs) in the fabrication of electronic devices. Their structures have been optimized by density functional theory (DFT), and the energy values of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), as well as their UV/Vis spectra, have been characterized. In order to study the electronic behavior of the organotin(IV) semiconductors, hetero-junction devices have been manufactured by a vacuum deposition process. Organic devices of the type glass/ITO/organotin(IV) complex/ZnPc/bathocuproine/Ag have been assembled by sequential sublimatory deposition. The devices have been characterized by X-ray diffraction (XRD), which revealed a considerable degree of crystallinity and a defined growth pattern in their constituent films. The optical band-gaps of the semiconductors in the devices have been measured to determine their electrical I(V) characteristics and hence their behavior as HILs. UV/Vis analysis has revealed that the deposition process generates flat hetero-junction structures free from impurities that are transparent to visible radiation and have an optical band-gap between 2.83 and 2.95 eV. On increasing the temperature, the devices show symmetrical J(V) behavior, indicative of ambipolarity. In both natural light and darkness, the devices show ohmic behavior at low voltages and space-charge-limited behavior at higher voltages. These dibutyltin(IV) complexes of 2-hydroxybenzylidene-1-indanone derivatives have proved to be suitable as HILs, and their behavior directly depends on radicals present in the tin complex.