Improved Efficiency of Organic Photovoltaic Cells by Incorporation of AuAg-Alloyed Nanoprisms

We successfully synthesized AuAg-alloyed nanoprisms (AuAgNPrisms) through the seed mediated and galvanic replacement approaches. By introducing the synthesized AuAgNPrisms at the buffer/active interface with an optimal concentration, we increased the power conversion efficiency of PTB7:PC70BM-based organic photovoltaic cells from 6.58% to 7.11%, the current density from 13.36 to 15.01 mA/cm2, corresponding to enhancement factors of 8.1% and 12.4%, respectively. According to our systematical study, we concluded that the incorporation of AuAgNPrisms not only increases light absorption in the active layer over a broad wavelength range but improves the exciton dissociation rate at the interface between PTB7 and PC70BM. With the incorporation of AuAgNPrisms, although the increase in the leakage current is observed, the carrier mobility is also improved apparently, yielding that the reduction in the fill factor is negligible. This work could contribute to the development of high efficiency and low cost organic solar cells.