Incorporating silver-SiO2 core-shell nanocubes for simultaneous broadband absorption and charge collection enhancements in organic solar cells

Abstract

A new type of silver nanoparticles, silver-SiO2 core-shell nanocubes (Ag NCs@SiO2), is developed for simultaneous broadband absorption and efficient charge collection enhancements in organic solar cells (OSCs), thereby improving short-circuit current density and power conversion efficiency (PCE). The effect of Ag NCs@SiO2, present at the bottom of active layer (PTB7:PC70BM), on the performance of OSCs were analyzed systematically. The results indicate that the broadband absorption enhancement in the OSCs is realized mainly due to the excitation of the strong localized surface plasmon resonance surrounding the Ag NCs@SiO2, supported by the theoretical simulation. While the efficient charge collection efficiency is attributed primarily to the improvement in vertical phase separation of donor/acceptor in the active layer, associated with the process integration of Ag NCs@SiO2 in the cell fabrication. The use of Ag NCs@SiO2 benefits the absorption enhancement and also prevents the exciton quenching and carrier charge recombination loss that would occur in cells with pure Ag NCs. The combination of these advantages results in an average PCE of 7.84% for cells with Ag NCs@SiO2, corresponding to a 13.6% increase in the efficiency as compared to that of the structurally identical control cell without Ag NCs@SiO2.