Transition-metal dichalcogenides (TMDs) attract increased attention for the development of donor-acceptor materials enabling improved light harvesting and optoelectronic applications. The development of novel donor-acceptor nanoensembles consisting of poly(3-thiophene sodium acetate) and ammonium functionalized MoS2 and WS2 was accomplished, while photoelectrochemical cells were fabricated and examined. Attractive interactions between the negatively charged carboxylate anion on the polythiophene backbone and the positively charged ammonium moieties on the TMDs enabled in a controlled way and in aqueous dispersions the electrostatic association of two species, evidenced upon titration experiments. A progressive quenching of the characteristic fluorescence emission of the polythiophene derivative at 555 nm revealed photoinduced intraensemble energy and/or electron transfer from the polymer to the conduction band of the two TMDs. Photoelectrochemical assays further confirmed the establishment of photoinduced charge-transfer processes in thin films, with distinct responses for the MoS2- and WS2-based systems. The MoS2-based ensemble exhibited enhanced photoanodic currents offering additional channels for hole transfer to the solution, whereas the WS2-based one displayed increased photocathodic currents providing supplementary pathways of electron transfer to the solution. Moreover, scan direction depending on photoanodic and photocathodic currents suggested the existence of yet unexploited photoinduced memory effects. These findings highlight the value of electrostatic interactions for the creation of novel donor-acceptor TMD-based ensembles and their relevance for managing the performance of photoelectrochemical and optoelectronic processes.
Keywords: electrostatic interactions; functionalization; photoelectrochemistry; photophysics; polythiophenes; transition-metal dichalcogenides.