Background:
In this article, experimentally, we fabricated the FASnI3 perovskite solar cells base on the SnF2
and SnF4-doped FASnI3 nano-thin film materials, and got the photoelectric conversion efficiency (PCE) were 6.5 % and
5.59 %, respectively. Theoretically, we wanted to know why the PCE of SnF2-doped FASnI3 is higher than the SnF4-
doped FASnI3.
Methods:
We built three kinds of model structures by the CASTEP, they were undoped and SnF2 and SnF4 doped FASnI3
perovskite structure models, respectively. The method was ultrasoft to calculate the interaction between electron-ion, with
an electron exchange correction method of generalized gradient approximation and Perdew-Burke-Emzerhof method.
Results:
We found the probabilities of energy transfer between SnF2 molecule and around it molecules were the lowest
among three structures. By integratedly analyzing optical properties, band structures, effective masses, and density of
states (DOS) et al, we considered that SnF2 doping was superior to SnF4 doping in maintaining photoelectric properties of
FASnI3. In addition, SnF2-doped FASnI3 possesses smaller hole effective mass than SnF4-dopedFASnI3, adding Sn4+ ion
into perovskite as an shallow acceptor energy level can effectively reduce the optical absorption properties, however,
adding Sn2+ ion into perovskite at an appropriate proportion can enhance its photoelectric performance of FASnI3.
Conclusion:
Sn4+ doping is a negative effect, and the Sn2+ doping is positive effect in promoting the photoelectric
performance of FASnI3 perovskite. We considered that SnF2 doping was superior to SnF4 doping in maintaining
photoelectric properties of FASnI3. We hope our results can help to deeply understand on Sn2+ and Sn4+ ion promoting the
stability and high efficiency of FASnI3, and help strive to develop the lead-free perovskite solar cells.
Influence of the Porosity of the TiO2 Film on the Performance of the Perovskite Solar Cell
