Negative capacitance based on isomeric polythiophene in action.

In this study, we demonstrated that arranging positive and negative capacitance materials in series, based on isomeric polythiophene, led to a notable increase in total capacitance. Furthermore, the application of negative capacitance (NC) technology in supercapacitor (SC) construction offers the potential for energy storage capabilities surpassing fundamental limits. Our findings suggest the feasibility of developing all-organic based energy storage devices with high capacitance.

Ionic liquid supported chitosan-g-SPA as a biopolymer-based single ion conducting solid polymer electrolyte for energy storage devices.

This article discusses the preparation of different grades of single-ion conducting quasi-solid polymer electrolytes (q-SPE) material (Chit-g-SPA-IL) based on biopolymer (chitosan), polyacrylic acid and DBU-acetate (DBUH+ AcO-) ionic liquid. Chit-SPA-60 %-IL exhibited the highest conductivity within the range of 10-4 S/cm. TGA analysis demonstrated the stability of electrolytes up to a temperature of 120 °C. SEM-EDS analysis unveiled the porous nature of the electrolyte and even distribution of ions throughout the matrix. It exhibited an electrochemical stability window (EWS) of 2.53 V with significant current density and an ionic transference number (ITN) of ~99.9 %. The temperature-dependent conductivity established an Arrhenius-type conduction mechanism with an activation energy of 0.149 eV for ion movement within the electrolyte matrix. The AC conductivity analysis emphasized the time-temperature independence of the ionic conduction mechanism. Dielectric analysis highlighted the capacitive nature of the electrolyte, underlining its substantial capacitance, while modulus studies indicated minimal influence from the electrode-electrolyte interface. Chit-SPA-60 %-IL at 30 °C included a self-diffusion coefficient of 4.57 × 10-5 m2/s, ionic mobility of 1.75 × 10-3 m2/Vs, and drift ionic velocity of 0.44 m/s. These findings makes SPE as a promising candidate for sodium-ion-based energy storage devices.

Isomeric polythiophene: a promising material for low voltage electronic devices.

In this investigation, we present empirical observations detailing the manifestation of substantial negative capacitance (NC), reaching up to -1 F, within iodine-doped isomeric polythiophene (IPTh-I2). NC observed in our case is not transient but stable enough to be measured for as long as the optimum concentration of the iodine dopant is available. In contrast, undoped isomeric polythiophene (IPTh) manifests a modest positive capacitance ranging from 30 to 60 µF. The concatenation of IPTh-I2 and IPTh in the series results in an augmentation of the total capacitance of the system (∼170 µF), exemplifying a characteristic feature of NC. Conversely, a bilayer configuration consisting of IPTh:IPTh exhibits a reduction in total capacitance by 38%. A notable amplification in the dielectric constant, escalating from 30 in IPTh to approximately 2000 in IPTh-I2, signifies extensive conformational and structural alterations arising from interactions between the doped polymer chain and various iodide species, attributing to the emergence of NC. Furthermore, we document a single-sided p-n junction diode with a low knee voltage (below 0.5 V) as a model device, illustrating the potential of IPTh as a promising material for the design and development of negative capacitance-based field-effect transistors. This research offers avenues for the scientific community to conceive low knee voltage-operating diodes, transistors, supercapacitors, and various other electronic devices based on all-organic semiconductors.