Effect Of Polymer Semiconductor Side Chain Modification And Element Substitution On The Performance Of Optoelectronic Devices For Fabric Sensing

With the fast development of interdisciplinary research between textile and other Fields such as electronics,computers,biology,materials,art,etc.,smart textile are drawing intense attention in the new era.Among smart textiles,smart wearable device is one of the hottest topics.For instance,as one of the most important part of smart wearable device,sensor's performance will directly affect the practical application of intelligent wearable device.Field-effect transistor(FET)is an important part of sensor logic circuit.It has the function of current amplification and switching.Photodetector(PD)is a device that transforms optical signal into electrical signal.It is a component commonly used in photoelectric display or sensor.Compared with traditional inorganic materials,polymer semiconductor materials have the advantages of low production cost,relatively simple preparation process,massive production capability and good flexibility.Therefore,organic photodetectors(OPD)and organic field-effect transistors(OFET)based on polymer semiconductor materials are more suitable for the fabrication of intelligent wearable devices.It is very important to prepare OFET devices and OPD devices for smart wearable devices with excellent performance and good market popularity.The main factors affecting the performance of these two optoelectronic devices are the raw materials and the device preparation process.Therefore,this thesis focuses on the following aspects:First,three types of Donor-donor polymer(PTVTN1,PTVTN2 and PTVTN3)were used to fabricate OFET devices.Meanwhile,grazing-incidence wide angle X-ray scattering(GIWAXS)technology and atomic force microscopy(AFM)were used to analyze the morphology of polymer films.It is found that the OFET devices based on Donor-donor polymers shows p-type behavior,indicating that the Donor-donor polymers are favorable for hole transport and are suitable for the fabrication of high-performance OFET devices.The mobility of the OFET devices after the side chain modification of the polymer increases by three orders of magnitude,indicating that the side chain modification is an effective method to improve the performance of the OFET device.Edgeon orientation is more favored for charge transport than face-on orientation in OFETs application.Second,three types of Donor-acceptor conjugated polymers(PCDTFBO,PCDTFBT and PCDTFBSe)were used to prepare OFET devices with different conductive channel lengths.The morphology of the three polymer films was studied by AFM.It is study found that the substitution of elements of the same main group of the Donor-acceptor conjugated polymer can improve the mobility and current switching ratio of OFET devices,indicating that element substitution is an effective method to improve device performance.The mobility and current switching ratio of OFET devices decrease with the increase of the conductive channel length of OFET devices.The threshold voltage of OFET devices increase with the increase of the conductive channel length of OFET devices.By mixing the two donor materials of PCIG-BDTT and PCIG-SBDT with the acceptor material ITIC,four types of OPD devices with different active layer thicknesses were prepared and tested.It is found that the donor polymer with short side chain length and deep HOMO energy level can effectively increase the hole injection barrier and improve the performance of OPD devices.The thickness of active layer of OPD devices will affect their performance.The EQE and light current density are negatively correlated with the active layer thickness of OPD devices,while the dark current density is positively correlated with the active layer thickness of OPD devices.