Although Organic Thin Film Transistors (TFTs) with an efficient operation have been manufactured and characterized since the last decade of the past century, some obscure points concerning the comprehension of their working mechanisms, such as the charge carrier accumulation mode and the device detriment, still need to be clarified. In this respect, the choice of a suitable in situ, real-time electrical characterization technique can furnish some exhaustive results in terms of the comprehension of charge carrier accumulation in devices based on organic small molecules, strongly affected by the thin film morphology. In particular, the analysis of the drain current (ID) evolution during the thin film growth can shed light on the layered distribution of the charge carriers induced by the gate voltage into the device channel. In addition, the opportune choice of dynamic measurement methods can open a new scenario for the analysis of TFTs working mechanisms, as the device operation can be affected by several problems such as charge trapping and related stress phenomena. In detail, as a consequence of both the nature of organic semiconductors and the manufacturing processes, an instability phenomenon due to charge trapping manifests in OTFTs by a decrease in time of the transfer current or, equivalently, by the shift of threshold voltage (?Vth) upon prolonged or repeated application of the gate bias. Here, the analysis of this stress phenomenon is developed by exploiting a dynamic study of trapping mechanisms in OTFTs based on the analysis of the hysteresis in transfer characteristics Beyond the importance played by the role of the experiment in the context of the device analysis, the choice of the manufacturing techniques allows to combine the easiness in materials processing and the possibility of engineering the device architectures, for instance via the patterning of the thin film surface. As this latter aspect is concerned, by combining the standard deposition technique based on organic powder sublimation to the solution processabilty of organics based on soft lithography fabrication methods, it is possible to manufacture prototypes of efficient ambipolar devices with the desired non conventional architectures. The detailed analysis of the above topics carried out in this contribution, is then developed to underline that both the experimental and the manufacturing planning can decidedly suggest some new strategies aimed to add further insight into the development of efficient organic device applications.
Non Conventional Experimental Approaches for the Analysis of Organic Thin Film Transistor Accumulation Mode, Working and Engineering of Device Architecture
D'Angelo Pasquale
2011
Abstract
Although Organic Thin Film Transistors (TFTs) with an efficient operation have been manufactured and characterized since the last decade of the past century, some obscure points concerning the comprehension of their working mechanisms, such as the charge carrier accumulation mode and the device detriment, still need to be clarified. In this respect, the choice of a suitable in situ, real-time electrical characterization technique can furnish some exhaustive results in terms of the comprehension of charge carrier accumulation in devices based on organic small molecules, strongly affected by the thin film morphology. In particular, the analysis of the drain current (ID) evolution during the thin film growth can shed light on the layered distribution of the charge carriers induced by the gate voltage into the device channel. In addition, the opportune choice of dynamic measurement methods can open a new scenario for the analysis of TFTs working mechanisms, as the device operation can be affected by several problems such as charge trapping and related stress phenomena. In detail, as a consequence of both the nature of organic semiconductors and the manufacturing processes, an instability phenomenon due to charge trapping manifests in OTFTs by a decrease in time of the transfer current or, equivalently, by the shift of threshold voltage (?Vth) upon prolonged or repeated application of the gate bias. Here, the analysis of this stress phenomenon is developed by exploiting a dynamic study of trapping mechanisms in OTFTs based on the analysis of the hysteresis in transfer characteristics Beyond the importance played by the role of the experiment in the context of the device analysis, the choice of the manufacturing techniques allows to combine the easiness in materials processing and the possibility of engineering the device architectures, for instance via the patterning of the thin film surface. As this latter aspect is concerned, by combining the standard deposition technique based on organic powder sublimation to the solution processabilty of organics based on soft lithography fabrication methods, it is possible to manufacture prototypes of efficient ambipolar devices with the desired non conventional architectures. The detailed analysis of the above topics carried out in this contribution, is then developed to underline that both the experimental and the manufacturing planning can decidedly suggest some new strategies aimed to add further insight into the development of efficient organic device applications.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
