Finely Tuned Composition in Conjugated Polyelectrolytes for Interfacial Engineering of Efficient Polymer Solar Cells

Conjugated polyelectrolytes (CPEs) work as highly efficient interface materials in organic optoelectronic devices. A series of CPEs is presented with tunable composition designed to study the evolution of backbones in CPEs and their effects on the properties and photovoltaic performance of the CPEs. The introduction of electron-withdrawing moieties into the main chains can improve the photostability, doping strength, and electron mobility of these CPEs. These CPEs can work well as cathode interfacial layers and enhance device performance by improving interface contact and inducing interface doping, thus enabling efficient polymer solar cells with power conversion efficiencies greater than 10%. Moreover, CPEs with a greater content of electron-withdrawing moieties possess greater mobility and can work as thickness-insensitive cathode interfacial layers, which indicates great potential for application in future large-scale polymer solar cells.