Effect of Aluminium Nanoparticles on the Performance of Bulk Heterojunction Organic Solar Cells

Al nanoparticles (NPs) are incorporated in the active layers to enhance the performance of organic solar cells (OSCs). The improved short circuit current J_sc and power conversion efficiency (PCE) for OSCs with Al NPs are observed. A final PCE of 3.66wt% is achieved, which is an improvement of more than 30wt% compared to a standard cell with a PCE of 2.84wt%. When the mass of Al NPs is 10wt% of OSCs, the device performance is best. The optical performance of OSCs reveals that the absorption from sunlight increases. The external quantum efficiency spectra suggests that the Al NPs in the active layers influence the efficiency of converting photons into electrons, which leads to the improvements in the photocurrent. The enhanced photovoltaic performance induced by incorporating Al NPs in the active layer is discussed in the terms of increasing charge separation at the donor-acceptor interface and the effectively decreasing transmission distance of charge in polymer.