The core-shell-structured NaYF4:Er3+,Yb3+@NaYF4:Eu3+ nanocrystals as dual-mode and multifunctional luminescent mechanism for high-performance dye-sensitized solar cells

Abstract The core-shell-structured NaYF4:Er3+,Yb3+@NaYF4:Eu3+ (NYFEY@NYFE) nanocrystals with dual-mode emission have been satisfactorily prepared through a solvothermal method utilizing oleic acid and octadecene. From the emission spectra of dual-mode luminescent nanocrystals, it could be seen that nanocrystals consisted of two disparate units, one supplying up-converting luminescence excited with the 980 nm laser and the other providing down-converting luminescence by means of ultraviolet excitation, which are assigned to 4S(3/2) → 4I(15/2) transitions of Er3+ and 5D0 → 7F2 transitions of Eu3+, separately. And then, a novel photoelectrode structure via introducing dual-mode luminescent materials was proposed. The photoelectric conversion efficiency of DSSCs with NYFEY@NYFE photoelectrode attains 7.37%, raised by a factor of 1.37 in comparison to that of the DSSCs without Eu3+ and Er3+ doping. The preparation of dual-mode NYFEY@NYFE not only has great significance to the study of material itself but its application in DSSCs, and can be also applied to other types of solar cells.