Density functional theory and experimental investigations of MWCNT-PDMS based triboelectric nanogenerator

Abstract

The emergence of triboelectric nanogenerators (TENG) have transformed the landscape of self-powered electronics and sensing mechanisms by exploiting the remarkable potential of innovative functional nanomaterials. However, there is a lack of theoretical in-depth analysis of the triboelectric devices. Herein, for the first time, the triboelectric performance of Polydimethylsiloxane (PDMS) and Multi-walled Carbon Nanotubes (MWCNT) - PDMS based TENG is unveiled by rigorous investigation of electronic structures through density functional theory (DFT) computations. Experimentally, PDMS and MWCNT-PDMS thin films are fabricated that are used as tribo-negative layers in the fabrication of TENGs. Further, the material characterisations are performed for the fabricated nanocomposite films. The output performance of TENGs is realised by using a dynamic test platform that imitates the finger tapping mechanism and the influence of contact surface area (1 cm 2 , 4 cm 2 , 9 cm 2 , 16 cm 2 , 25 cm 2 ) between triboelectric layers on open circuit voltage (V oc ) of TENGs is investigated. The outcomes demonstrate linear increase in V oc corresponding to increase in contact area of TENG. With a contact area of 1 cm 2 , the maximum peak-to-peak open circuit voltage (V mpp ) is recorded to be 32.2 V and 94.2 V for PDMS and MWCNT-PDMS based TENG respectively. An increase in V mpp by ~65% is synergistically validated by ~95% decrease in band gap endowing to addition of MWCNT into PDMS elastomer. Importantly, the energy band gap analysis is quantified by calculating HOMO/LUMO states and density of states responsible for the development of electric potential which can be used for small power applications. • Analysing the enhancement in triboelectric performance of PDMS on addition of MWCNT using density functional theory (DFT) calculations. • MWCNT-PDMS based TENG exhibited ~65% higher open circuit voltage than pure PDMS TENG. • Band gap reduced by ~95% on incorporation of MWCNT into PDMS elastomer. • Increased DOS peak intensity in valence band and conduction band along with the shift towards fermi level provides assistance to charge transport in comparison to pristine PDMS • Experimental outcomes are synergistically validated by DFT findings.