Among the various forms of natural energies, heat is the most prevalent and least harvested energy. Scavenging and detecting stray thermal energy for conversion into electrical energy can provide a cost-effective and reliable energy source for modern electrical appliances and sensor applications. Along with this, flexible devices have attracted considerable attention in scientific and industrial communities as wearable and implantable harvesters in addition to traditional thermal sensor applications. This review mainly discusses thermal energy conversion through pyroelectric phenomena in various lead-free as well as lead-based ceramics and polymers for flexible pyroelectric energy harvesting and sensor applications. The corresponding thermodynamic heat cycles and figures of merit of the pyroelectric materials for energy harvesting and heat sensing applications are also briefly discussed. Moreover, this study provides guidance on designing pyroelectric materials for flexible pyroelectric and hybrid energy harvesting.

The electrocaloric effect (ECE), which refers to changes in the temperature of a material when an electric field is applied to or removed from the material, is one of the key phenomena of future highly efficient solid-state refrigeration devices.

Future nanoelectronics for nonvolatile memory elements require novel materials and devices that can switch logic states with a low power consumption, minimum heat dissipation, high-circuit density, fast switching speed, large endurance and long charge retention period. Herein, we report novel high resistance resistive switching in a polar beta-polyvinylidene fluoride (β-PVDF) and graphene oxide (GO) composite. A high resistance switching ratio was achieved without the realization of the essential current-filament forming condition mainly responsible for switching the device from high to low resistance states. β-PVDF is a well known ferroelectric/piezoelectric material which changes shape and size after application of an external electric field. We propose a model which describes how the present β-PVDF–GO composite changes shape after application of an external electric field (E) which provides a favorable environment for the formation of the current linkage path of GO in the PVDF matrix. The applied positive SET electric fields (+E) switch the composite from a high to a low resistance state, which further re-switches from a low to a high resistance state under negative RE-SET electric fields (−E). The positive and negative E-fields are responsible for the contraction and expansion of β-PVDF, respectively, redox reactions between GO and adsorbed water, oxygen migrations, and/or metal diffusion from the electrode to the β-PVDF–GO matrix. The above mentioned characteristics of the composite allows switching from one high resistance state to another high resistance state. The switching current lies below the range of 10–100 μA with an exceptionally high switching ratio, which meets one of the pre-requisite criteria of low power nanoelectronics memristors.

This research explores a novel two-terminal heterostructure of the Pt/Cu ₂ Se/Sb ₂ Se ₃ /FTO memristor, which exhibited essential biological synaptic functions.

An ultra thin film (∼5 nm) high-k Hafnium oxide dielectric, grown on a doped p-Si(100) substrate by the atomic layer deposition technique has been investigated for resistive and capacitive switching with and without illumination of light. As grown samples illustrate small non-switching leakage current under high applied electric fields and probe frequencies and trap charge assisted counter-clockwise capacitance–voltage behavior. A unique resistance switching was observed under illumination of 15–60 mW light. In the first cycle, the light assisted switching provide a 10⁴ : 1 resistance ratio, which diminishes in the next cycle onward, which may be due to irreversible charge injection in the oxide layers. The band offset and band match-up energy diagram for the charge carriers responsible for resistive switching and charge trapping near the interface have been demonstrated under the application of a bias electric field and light.