* 발표자 : 김민제
* 제목 : Improving the Performances of Ambipolar Transistors based on Rigid Planar Low Band Gap Polymers through the Use of a Binary Solvent System
* 내용 : The carrier mobility in an organic thin film transistor (OTFT) is strongly associated with the semiconducting film morphology. The shrewd ion of processing solvents is critical for managing the morphology of the semiconducting polymer film. Here, we report the synthesis of a new low band gap planar polymer composed of PTTDPP-DT-DTT and the performance improvements of the PTTDPP-DT-DTT-based OTFTs obtained using a binary solvent system: (i) chloroform (CF):toluene (Tol), (ii) CF:chlorobenzene (CB), and (iii) CF:o-dichlorobenzene (DCB) (volume ratio of 16:1). The high boiling points (bps) of the added solvents increased the film crystallinity, and an edge-on orientation among the molecules was promoted. Thus, the use of CF:DCB yielded the highest carrier mobility obtained among the devices tested. Thermal annealing further enhanced the carrier mobility of the CF:DCB device. Atomic force microscopy images confirmed that the thermally annealed CF:DCB polymer film displayed the most fibrous character. This work emphasizes that the proper ion of processing solvent is critical for exploiting the beneficial characteristics of rigid planar conjugated polymer semiconductors for the preparation of high-performance OTFTs.
* 발표자 : 호동해
* 제목 : Stretchable and Multimodal All Graphene E-Skin
* 내용 : To develop artificial skin mimic multifunctional human skin, sensor cell with flexible materials could be functionalized to collect signals from external stimulus and give a feedback to customs. Organic field effect transistors (OFETs) active matrix has been studied in E&8211skin matrix. However, in the geometry of E&8211skin based on FET active matrix, there is a great challenge to integrate multifunctional sensing components due to its structure limitation. In this manuscript, we demonstrated, for the first time, all-graphene based transparent and flexible multifunctional sensors matrix. In this matrix, three different functional sensors (including humidity, temperature and pressure sensors) were judiciously integrated in a layer-by-layer geometry through a simple lamination and degassing method. CVD-Graphene was adopted as electrodes for all these three sensor, while GO and rGO could functionalize as the active sensing materials for humidity and temperature sensors, respectively. GO humidity sensor on PDMS substrate was crisscross laminated on top of rGO temperature sensor, both of which have the same geometry. PDMS substrate was sandwiched between two CVD-Gr electrodes and worked as the active layer in the capacitive pressure sensor. Fully fabricated device characterized with specified stimulus temperature, humidity and pressure. Furthermore we demonstrated each sensors are working independently with specified stimulus only. Finally veritably mimic the multifunction of human skin, output signals induced by external stimulation were collected from each sensor in this multifunctional sensors matrix to confirm the reliability of each sensor without signal crosstalk. From this work, we suggested a facile fabrication process combined with versatile graphene derivatives to transparent and conformable E-skin application, which overcome the conventional complex fabrication process to E-skin.