No abstract

High-performance flexible organic field-effect transistors with natural protein gelatin as a dielectric layer and solution-processed TIPS-pentacene as an active layer were fabricated on a flexible poly(ethyleneterephthalate) substrate. The fabricated devices exhibited high performance and electromechanical stability, demonstrating high field-effect mobility with near-zero threshold voltage and the I on to I off ratio approaching 10 5 with a low operating voltage of −5 V. Devices exhibited highly stable electrical characteristics under multiple transfer scan measurements. The flexible nature of these devices was tested through the tensile strain test by subjecting them to a 5 mm bending radius. High electromechanical stability was observed with minuscule variation in the electrical parameters under strain application. These flexible devices were demonstrated for circuit and sensing applications. Under the humidity exposure test, the devices responded quickly with rapid response and recovery time and acted as a humidity sensor. This property was utilized for real time health monitoring applications by testing these devices as a breath rate analyzer. In addition, to test the credibility of these flexible devices in circuit applications, the external load invertor circuits were demonstrated before and after applying strain to these devices.

No abstract

No abstract

Organic field-effect transistors (OFETs) have opened up new possibilities as key elements for skinlike intelligent systems, due to the capability of possessing multiple functionalities. Here, multifunctional OFET devices based on gelatin, a natural biopolymer gate dielectric, and TIPS-pentacene as an organic semiconductor are extensively explored. Gelatin is combined with a thin high-k HfO2 dielectric layer deposited by atomic layer deposition (ALD) to achieve a low leakage current and low-voltage operation. The natural biopolymer offers a better semiconductor:dielectric interface, leading to better charge conduction in the devices, along with an enhancement of sensing capabilities giving additional functionality. These fabricated flexible OFET devices exhibit excellent electrical characteristics with a high field-effect mobility reaching over 2 cm2/(V s) (extracted with C i at 1 kHz), a low subthreshold swing (SS) of ∼200 mV/dec, and a high current on–off (I on/I off) ratio at a low operating voltage of −5 V with excellent electrical and mechanical stability. Moreover, circuit and multiparameter sensing capabilities for visible and UV light, as well as for humidity and breath rate, have been successfully demonstrated for these devices. Our results indicate that these multifunctional OFET devices can open up a plethora of opportunities for practical applications such as real-time health and environmental monitoring.

An expression for load for maximum power transfer from a real solar cell, having resistive and current leakage losses, has been obtained using Lagrange’s method of undetermined multipliers for solving the transcendental current-voltage relationship. The theoretical results are compared with the experimental measurements of the optimum load for p-n junction solar cells for various illumination levels.

No abstract

No abstract