Organic Solar Cells Incorporated With Auag Alloyed Nanoprisms

Compared to the inorganic photovoltaic cells,organic photovoltaic cells(OPVs)still suffer from the relatively lower power conversion efficiency(PCE),though they have many advantages such as low cost,material abundance,large area production,good flexibility,etc.An effective way to improve PCE of OPVs is to introduce metal nanoparticles.By inducing surface plasmon polaritons(SPPs),the enhanced localized field effect as well as the strong light scattering effect can be produced by surrounding metallic nanoparticles,yielding the enhanced light absorption in the active layer.Moreover,the latest researches suggested that metal nanoparticles can improve the electrical performances of OPVs as well.This paper has following contents:(1)In this paper,we successfully synthesized AuAg alloyed nanoprisms(AuAgNPrisms)through the seed mediated and galvanic replacement approaches.By introducing the synthesized AuAg NPrisms at the buffer/active interface with an optimal concentration,we increased the power convert efficiency(PCE)of PTB7:PC70BM based organic photovoltaic cells from 6.58% to 7.11%,the current density from 13.36mA/cm2 to 15.01mA/cm2,corresponding to enhancement factors of 8.1% and 12.4%,respectively.According to our systematical study,we concluded that the incorporation of Au AgNPrisms not only increases light absorption in the active layer over a broad wavelength range,but also improves the exciton dissociation rate at the interface between PTB7 and PC70 BM.With the incorporation of AuAgNPrisms,although the increase in the leakage current is observed,the increase in the carrier mobilityis 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.(2)In order to further improve the dispersibility and stability of AuAg nanoprisms,we used(Tetraethyl orthosilicte)TEOS to successfully coat the Au Ag nanoprisms with a layer of silica under alkaline conditions.The shell acts to prevent the internal metal particles from being oxidized.The UV-Vis absorption spectra and SEM images show that the Au Ag nanoprisms was coated by silica successfully.After this process AuAg nanoprisms can be dissolved in any solvent,so there will be a good potential for the application of AuAg nanoprisms in the future.Finally,we summarize the work of this paper,and put forward the future research.