Enhanced Output Performance of Triboelectric Nanogenerator Based on Sulfur-Rich Polymer with Controlled Composition Gradient

Elemental sulfur of seven million tonnes is annually generated as a by-product from petroleum refining processes. Hence, the upcycling of elemental sulfur has gained significant attention owing to its high economic feasibility and environmental-friendliness. In previous reports, the sulfur-rich polymer (SRP) is utilized for the high-performance negatively chargeable friction layer in a triboelectric nanogenerator (TENG). Because the SRP has the highest electron affinity of –200 kJ mol^-1 in the periodic table except for halogenic elements and precious metals like Au, Pt. In this study, we introduce a structural approach with composition gradient for improving TENG performance. A thin dielectric layer is typically favorable for high performance due to increased charge induction, but excessive thinness reduces surface charge density due to charge recombination. To prevent the recombination, a charge trapping layer (CTL) is employed for enhancement of surface charge density. Increasing sulfur content in SRP leads to a higher dielectric constant, resulting in the generation of more charge through triboelectrification. At the same time, the benzene content decreases, which reduces charge capture ability. This is because aromatic polymers have non-uniform energy levels along their polymer chain, containing numerous charge trapping sites. We optimize TENG performance by creating a monolithic film with spatially controlled elemental sulfur and benzene content through dynamic covalent bonding by the thermal processing of two films with different sulfur contents.<gdiv></gdiv>