Natural and Eco-friendly Biopolymer Dielectric for Low Cost Green Electronic

We present our achievements in the fabrication and characterization of Organic Field Effect Transistors using natural gums, which are non-toxic, water soluble, and biodegradable polymers, as gate dielectrics. We perform material characterizations such as X-ray diffraction (XRD), contact angle measurements, Thermogravimetric Analysis (TGA) and dielectric characterizations, of Gum Arabic (GA), Almond Gum (AG), Cashew Gum (CG) and Khaya Gum (KG). GA is derived from exudates of acacia species such as acacia Senegal and acacia seyal which are trees growing in Sub-Saharan region of Africa. Almond gum is produced by almond trees as a result of either a disease called gummosis or a mechanical injury. The calculated dielectric constant at 1 kHz of GA and AG were around 30 and between 7-9, respectively. Additionally, OFETs properties using gums as the gate dielectrics have been studied. As the active material, poly(3,6-di(2-thien-5-yl)-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione)thieno[3,2-b]thiophene) (DPPTTT)-polymethyl methacrylate (PMMA) 70:30 blend was used. The fabricated OFETs operate at 3 V. The OFETs using gum Arabic as the gate dielectric displayed a saturated field effect mobility µsat = 0.6 cm2/Vs, a threshold voltage Vth = -0.35 V, a subthreshold swing ss = 350 mV/dec, and an on/off current ratio ION/OFF > 102. Those using almond gum was µsat = 0.75 cm2/Vs, Vth = -0.8 V, ss = 266 mV/dec and ION/OFF =103. In light of these obtained results, gums emerge as promising gate dielectrics for OFET applications especially when the requirements of ecofriendly manufacturing of electronics are considered.