Generation of Additional Logic States in Molecular-Switch Embedded Anti-Ambipolar Transistor for Realizing Multi-Valued Logic System

Developing logic circuit systems that have high data throughput levels and mechanical flexibility is becoming more and more important with expanding market of AI and autonomous driving. It is known that the organic thin film transistor can meet the above conditions. However, organic thin film transistors have weaknesses in high-temperature processes and fine patterning. Therefore, there is a limit to increasing the speed of data process by improving the degree of integration. As an alternative to solving this problem, a logic (MVL) system has been proposed. The traditional logic inverter system can perform 2ⁿ processing operations, but the triangular logic inverter system can process 3ⁿ processing operations, which is about 160% more efficient than the traditional logic inverter.<br/><br/>The mechanism of multi-valued logic system is described below. If n-type semiconductor and p-type semiconductor are in lateral contact, the current graph will show the effects like ‘union’ in the sets. On the other hand, if two semiconductors contact in vertical way, the current graph will show the effects of ‘intersection’. Interestingly, in the case of one semiconductor gets over the other at lateral contact to create both lateral and vertical contacts, both effects happen and an additional middle logic state could be generated. This heterojunction, which is called anti-ambipolar, changes the sign of the slope of the drain electrode current value in a specific voltage range. However, as we are planning to make higher level of base, you need a very complex structure. Therefore, a new strategy is needed to implement a high-base logic system. Accordingly, we tried to introduce molecular switch to develop MVL circuits.<br/><br/>As a result, diarylethene, a molecular switch that can change its structure by light, was able to successfully decrease the current level of embedded organic polymer. In the electric field condition, charge carriers move from one electrode to the other. When UV light is irradiated to DAE, the HOMO level of DAE rises as the molecule becomes closed form. Then UV irradiation causes them to be trapped in the HOMO of DAE, which leads to the reduction of overall current level and make additional middle logic state. The reduced current and the shift of NTC range allow us to distinguish different states.<br/><br/>In this work, We demonstrated anti-ambipolar transistor(AAT) and MVL system that used it. Most of DAEs were successfully co-deposited with organic semi-conductor(DNTT). It is believed that molecular switch that has less sterically hindered characteristics obtained better drain current and mobility due to securing free volume for molecular switching.