Multifunctional Organic Neuromorphic Transistors by Controlling the Ferroelectricity of P(VDF-TrFE) via Photocrosslinking

The beginning of the era of the big data, Internet of Things (IoT) and AI (Artificial Intelligence), it is necessary to process the massive amount of data. So far, many data processing method follows the classical Von Neumann’s computer architecture. With this method as the data processes in series, as the amount of data increase, it is very inefficient way. So many researchers are trying to realize the neuron networking by mimicking the human brain for the parallel data processing method and it calls neuromorphic transistors. Additionally, the advantages of using organic materials like mechanical properties that match with human tissue and the working mechanisms of those devices are compatible with human physiology. [1,2]<br/>So, in the organic neuromorphic researchers are focused on mimicking the human brain, especially synaptic function. But these transistors cannot be regarded as unique multifunctional devices because all bult-in functions are mutually combined. To address this, we focus on the separation of electrical switching and data storage functions in organic ferroelectric memory transistors [3].<br/><br/>This study was conducted to create a multifunctional neuromorphic device by mixing P(VDF-TrFE) (poly(vinylideneflurodie-trifluoroethylene)), a ferroelectric polymer, and various photocrosslinker 2Bx, 4Bx and 6Bx. [4] High permittivity needed for electrical switching and the ferroelectricity needed for data storage become compatible by restricting the motion of P(VDF-TrFE) via photocrosslinking. When irradiating the UV light to the photocrosslinker, compared to the reference photocrosslinker, the 4Bx and 6Bx have 2 times and 3 times more azide groups. So, with the less amount of concentration of 4Bx and 6Bx, we observed almost the same results with using more concentration of 2Bx. Additionally depend on the difference of ferroelectricity, the neuromorphic electrical properties like Short-term potentiation (STP), Long-term potentiation (LTP) and Long-term depression (LTD) etc. showed totally different results.<br/><br/>As a result, we realized multifunctional organic neuromorphic thin film transistors which has both switching and data storage property with the photocrosslinking of the P(VDF-TrFE) films. Also, with the various photocrosslinker, we successfully observed the increased ferroelectricity modulation efficiency of P(VDF-TrFE) films.