Metal Nanoclusters for Interface Engineering and Improved Photovoltaic Performance in Organic Solar Cells

Copper nanoclusters (Cu NCs), synthesized by a one-pot synthesis method, were theoretically shown to exhibit a dipole moment and cause work function modification on a surface as observed from Kelvin probe measurement. Here, Cu NCs were used as an interfacial modifier in organic solar cells (OSCs). The effective engineering of the electron transporting layer/active layer interface using Cu NCs resulted in improved photovoltaic performance in fullerene and non-fullerene based OSCs. On insertion of Cu NCs, the best power conversion efficiency (PCE) obtained for the non-fullerene based system was 15.83% compared to 14.22% for the control device, while the PCE increased from 7.79% to 8.62% for the fullerene based system. The interface modification resulted in reduced recombination losses and charge accumulation at the interfaces. The improved performance in Cu NC interfaced devices is attributed to work function modification, enabling reduced energy barrier and enhanced charge collection.