Band well structure with localized states for enhanced charge accumulation on Triboelectrification

Abstract

We describe an triboelectric nanogenerator embedded with multilayers consisted of PDMS:electron trapping layer (ETL):PDMS (E-TENG) with oxygen vacancies, producing more localized states in the energy gap, that can accumulate much more transferred electrons by triboelectrification at ETL, thereby enhancing surface charge density of E-TENG. We suggest a working mechanism of an E-TENG with band diagram including electron/ charge flows by investigating electrical, chemical and physical properties and suggest the optimal characteristics of ETL depending on the degree of oxygen vacancies, rich, medium and poor, for high performance of E-TENG. Furthermore, we propose the main factors such as localized states of ETL and difference conduction band between polymer and ETL with band diagram as a band well structure, presented space for electrons/charges accumulation, for high surface charge density of E-TENG. As a results, maximum output performance of E-TENG with rich oxygen vacancies of ETL (E-TENG-R) is 618.7 V, 40.4 mu A and 22.8 nC/cm2, more than three-fold enhancement compare to pristine TENG. Finally, to effectively generate electrical energy, we apply E-TENG-R to kinematic system as a hand handled gear-cam system, 36 times enhancement of working frequency, with ground structure (EHGS) which produces the maximum 200 V and 100 mu A. We charged 110 mu F until 5.2 V for 25 s using EHGS and achieved operation of wireless humidity sensor system.