Research On Performance Enhancement Of Organic Field-Effect Transistor Memory Based On TIPS-pentacene/PS

With the rapid development of information technology,the importance of high-performance organic field-effect transistor memory has become increasingly evident.The method of forming phase-separated thin films through one-step spin-coating of small molecule semiconductor and polymer blend solutions has been widely used in the fabrication of organic field-effect transistor memory due to its greatly simplified operation process.However,due to the strong intermolecular forces of polymer materials,as well as the shortcomings of spin-coating processes,phase-separated film formed by spin-coating often suffer from poor continuity and high roughness,resulting in low yield and hindering charge transport.In this thesis,small molecule semiconductor TIPS-pentacene and polymer PS are used as the research objects and the morphology of active layer is improved by reducing the molecular weight of the polymer,vaporizing pentacene and introducing OTCS self-assembled films in different states to modify the substrate appearance.This thesis mainly focuses on the evolution law of thin film morphology and the correlation between electrical properties and thin film morphology.The main research contents and results are as follows:The first part of the thesis focuses on the fabrication of organic field-effect transistor using TIPS-pentacene/PS phase-separated thin films.Firstly,PS with a molecular weight of 280 k Da is selected as a representative to investigate the optimal blending ratio for achieving the highest quality TIPS-pentacene/PS phase-separated thin film.Based on this,improved phase-separated film morphology is achieved by changing the molecular weight of PS and vaporizing pentacene on the active layer.As a result,the charge carrier mobility is increased from 0.0077 cm²V^-1s^-1to0.022 cm²V^-1s^-1,and the yield of high-quality devices reaches from 30%to 80%.Based on the aforementioned thesis,the substrate is surface-modified by introducing an OTCS self-assembled layer.By adjusting the contact angle of the OTCS self-assembled layer,superior stability is achieved compared to devices with an OTCS/pentacene/electrode structure.Following more than 100 times of read-write-erase operations,both the current ratios between the positive write state and erase state,as well as between the negative write state and erase state,remain at a level of 10³.Furthermore.after a retention test exceeding 10⁴s,the current ratios of the positive write state and erase state,as well as the negative write state and erase state,respectively,maintain values of 10² and 10⁴.Based on the thesis conducted in the second part,modification of the OTCS self-assembled layer is achieved through ultraviolet irradiation.Furthermore,the performance of the devices is regulated by adjusting the volume ratio of the TIPS-pentacene/PS mixed solution and the thickness of the layer of pentacene deposited by thermal evaporation.The carrier mobility is improved to 0.10 cm²V^-1s^-1,and the memory window is increased from 10 V to 30 V.Moreover,after undergoing over 100 times of read-write-erase operations,the current ratios between the positive write state and erase state,as well as between the negative write state and erase state,remain higher than 10².Additionally,following the retention test exceeding 10⁴s,the current ratios of the positive write state and erase state,as well as the negative write state and erase state,maintain current ratios exceeding 10³.