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Browsing Pusat Pengajian Kejuruteraan Bahan dan Sumber Mineral - Tesis by Author "Ali, Muhammad Zeshan"

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    Stretchable pedot:pss (poly(3,4- ethylenedioxythiophene)- poly(styrenesulfonate)) for electronic applications
    (2022-08-01)
    Ali, Muhammad Zeshan
    PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)), conjugated conducting polymer, is the most attractive among conducting polymers due to tunable electrical conductivity, good chemical and environmental stability and facile processability for variety of stretchable optoelectronic, thermoelectric and sensor applications. Pristine PEDOT:PSS films have low conductivity of <1 S/cm and limited stretchability (<5%). This research study is aimed to improve conductivity of PEDOT:PSS for transparent electrode with focus on mechanism of conductivity improvement. Post-treatment of PEDOT:PSS by DMSO solvent and HBr-DMSO solution improved conductivity of PEDOT:PSS due to charge screening between PEDOT and PSS, washing away of PSSH and improved oxidation. Improved conductivity at high transparency achieved competitive figure of merit of ~37 for transparent electrode for transparent optoelectronic applications. Thermoelectric generator based on PEDOT:PSS with focus on mechanism of improvement in conductivity, Seebeck coefficient and concurrent improvement of thermoelectric (TE) properties are investigated in the study. One-step pre-treatment by triflic acid improved TE properties, simultaneously leading to power factor of 94 µWm-1K-2 due to increase order of long-range crystal packing as well as hopping between newly generated DOS. The developed thermoelectric generator resulted in the thermovoltage of 2.0 mV at temperature difference of 15 K. Development of a strain sensor along with development of conductive ink based on PEDOT:PSS and poly (dimethyl siloxane) (PDMS) is also the focus of the study. Conductive ink based on hydrophilic PEDOT:PSS and hydrophobic PDMS is developed by using bifunctional silane coupling agent of (3-glycidoxypropyl) trimethoxy silane (GPTMS). Low percolation threshold is achieved due to good mixing of phases and tunneling percolation mechanism of conduction. The developed strain sensor is 50% stretchable with high gauge factor of 146, fast response time of 130 milli seconds, and successfully captures finger and wrist motions. Chemical treatment of pristine PEDOT:PSS improve conductivity and thermoelectric properties for optoelectronic and stretchable applications.