Properties of silver nanostructures incorporated perovskite based thin films for solar cell applications

Silver nanostructures (Ag nanoparticles, Ag@SiO₂ core-shell nanoparticles & Ag nanowires) were firstly added into aluminum oxide isopropanol solution to form cellular Al₂O₃ mesoporous layers for perovskite solar cell applications, respectively. Then CH₃NH₃PbI₃ organic-inorganic hybrid perovskites were fabricated and attached to this matrix. Absorption spectra of Al₂O₃/CH₃NH₃PbI₃ composite and CH₃NH₃PbI₃ were found to be basically the same in the visible region, indicating that Al₂O₃ had less impact on the absorption performance of CH₃NH₃PbI₃. However, the incorporation of silver nanostructures could significantly improve the absorption properties of the perovskites, and the best performance could be achieved with the concentration ratios of Ag nanoparticles, Ag@SiO₂ core-shell nanoparticles and Ag nanowires of 0.15, 0.3 and 0.15, respectively. Further increasing the concentration of silver incorporation would probably cause halogenation and reduce the absorption properties of CH₃NH₃PbI₃. In addition, the efficiency of perovskite solar cell could be improved from original 6.28% to 7.09% after addition of Ag@SiO₂ core-shell nanoparticles. In contrast, the incorporation of Ag nanoparticles & nanowires tended to reduce the short circuit current density and conversion efficiency of the fabricated solar cells, because they could prolong the internal carrier transport path and hence increase the recombination probability of the electron-hole pairs.