| Organic thin film transistor(OFET)has become a research hotspot in organic electronic devices because of its low cost,flexibility,and large-area fabrication.The main challenges are low mobility,threshold voltage regulation and so on.The accumulation-type organic heterojunction structure can effectively increase the carrier concentration and fill the trap states in the semiconductor organic thin film,thereby increasing the on-state current and regulating the threshold voltage.At the same time,it also expands the application in sensing.It is of great significance for the in-depth study of OFET with heterojunction structure.In this paper,starting from the basic characteristics of organic semiconductor materials and thin films,the formation mechanism of the organic heterojunction accumulation effect is analyzed,the heterojunction structure is introduced into the OFET,the influence on the formation of bipolar OFET is studied,and the BFPDI is prepared.Heterojunction OFET to explore their applications in ammonia gas sensing.Firstly,starting with the mechanism of heterojunction,pentacene and BFPDI are used to form heterojunction,and its action mechanism is systematically analyzed.Through the method of quantitative analysis,the continuity between layers and the crystallization quality of modified layer are controlled,the model is established,the influence of both on the accumulation effect of heterojunction is deeply explored,and the action mechanism of heterojunction is analyzed.Secondly,combining the heterojunction theory with the practical application of OFET,an OFET ammonia gas sensor with heterojunction structure is developed by using the reducibility of ammonia gas and the special carrier accumulation effect of heterojunction.Through the gas sensing experiment of different concentrations of ammonia gas,the extremely low concentration detection of 0.5ppm hydrazine hydrate gas and 3ppm ammonia gas is realized at room temperature The sensing performance is systematically analyzed from multiple angles such as repeatability.It is proved that the heterojunction OFET sensor has the characteristics of high sensitivity,fast response and high stability.Finally,the heterojunction theory is applied to the research of bipolar OFET.Through the comparison and analysis of the advantages and disadvantages of the previous structures,a new structure to realize the bipolarity of the OFET is proposed.The carrier transport mode improves the bipolar transport characteristics of the OFET. |
