Construction of Imine-Linked Nanoparticle Organic Networks for Field Effect Transistors: Wet Chemical versus Mechanochemical Approach

Metal nanoparticles (MNPs) in heterogeneous form have shown impressive potential for a range of applications in optoelectronics, heterogeneous catalysis, and sensing. Various strategies with varying degrees of success have been adopted over the years for the heterogenization of MNPs, including anchoring and/or encapsulation of MNPs in polymers, zeolites, silica, etc. However, these strategies suffer from unavoidable drawbacks, such as leaching and agglomeration-induced deactivation. In this work, we developed a new approach to heterogenize MNPs as networks [nanoparticle organic networks (NONs)] by reacting amine-functionalized MNPs (as nodes) with dialdehydic linkers (as organic struts) at room temperature. Importantly, a green and sustainable mechanochemical synthetic strategy was conceptualized and employed to overcome the limitations of the wet chemical approach to NON synthesis. Capitalizing on the processable powder form of NONs and the inherent conductivity of the MNPs, we introduced NON materials in semiconducting polymer (SP)-based field effect transistors (FETs). An enhancement of the in-plane charge transport mobility by 2 orders in magnitude and a 760% increase in photoresponsivity compared to the pristine SP indicated the efficacy of NONs "as an emerging class of materials" for optoelectronic applications. We correlate this enhancement in performance to the NON-induced structural ordering of the SP and passivation of trap states, which is supported by a higher value of the order parameter and small crystallite size of SP as calculated from X-ray diffraction analysis.