Abstract
In this paper, the effects of two different solvents on the Schottky barrier of ITO/ blend of methyl red dye—fullerene nanoparticles/Al - M electrode have been studied. We have taken chlorobenzene solvent and toluene solvent. Three different devices have been made by taking three different weight ratios of the dye—nanoparticles blend which is 1:1, 1:2, and 2:1. The estimation of the interfacial Schottky barrier at the junction of metal-organic dye is estimated using the device’s dark I—V plot. Interfacial Schottky barrier at the metal-organic junction is least for 2:1 weight ratio of dye - nanoparticle blend in chlorobenzene solvent but for toluene solvent, the Schottky barrier is least for 1:2 weight ratio of dye—nanoparticle blend. The lowering of barrier height at 2:1 and 1:2 ratios in Schottky barrier contacts prepared with chlorobenzene and toluene solvents can be attributed to the filling up of traps at the metal-organic layer interface. The Norde method is also used to check the consistency of the obtained value of the Schottky barrier measured from I—V plots. Reduction in Schottky barrier results in improved current injection process at the metal-organic interface.
Highlights
Organic thin-film devices have gained substantial consideration in recent years as they are flexible, cost-effective and they are easy to tune, and have large area solution-processable fabrication techniques [1,2,3,4]
In our earlier works [14, 15], we have reported that with fullerene nanoparticles, the Schottky barrier gets improved in organic devices resulting in improved charge injection as fullerene nanoparticles are highly electronegative carbon nanoparticles and they act as electron acceptors
SEM images are taken for methyl red dye-based organic devices consisting of fullerene nanoparticles in both chlorobenzene solvent and toluene solvent respectively
Summary
Organic thin-film devices have gained substantial consideration in recent years as they are flexible, cost-effective and they are easy to tune, and have large area solution-processable fabrication techniques [1,2,3,4]. One of the limitations is when these organic dye-based thin films are sandwiched in between two metal electrodes, a high Schottky barrier occurs at one of the metal-organic (M/O) interfaces which lowers the injection of majority charge carriers [5, 6]. Organic semiconductors differ significantly from their inorganic counterparts, as they are amorphous in nature [9] Their electronic states are highly localized, and the charge injection process is described as thermally assisted tunneling from the delocalized states of the metal into the localized states of the organic semiconductor. The charge injection process is described as thermally assisted tunneling from the delocalized states of the metal into the localized states of the organic semiconductor and it plays a crucial role in the electrical properties of organic dye-based devices and is sometimes even more dominant than charge transport within the organic semiconductor [10]. The estimated barrier height at metal-organic layer interface is always greater than 0.30 eV and due to this, we have considered only injection limited current (ILC) and we have not considered space charge limiting current (SCLC) effect on the current mechanism [19]
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