摘要
The presence of numerous trap states on the perovskite surface severely affects the performance of inorganic CsPbI_(2)Br perovskite solar cells.Surface modification has been proven to be an effective strategy to passivate the surface trap states of CsPbI_(2)Br perovskite.However,most modifiers behave high volatility and insulation,not enough to further develop the CsPbI_(2)Br solar cells.Herein,an ionic liquid of 1-viny-3-propionate ethyl imidazolium chloride([PEVIM]Cl)is applied to modify the CsPbI_(2)Br film surface,yielding a compact film with enhanced crystallinity.The surface trap states of CsPbI_(2)Br film are effectively passivated via the interaction between carbonyl group of[PEVIM]Cl and uncoordinated metal cations of CsPbI_(2)Br perovskite,leading to charge recombination suppression and charge transport enhancement.Consequently,the power conversion efficiency(PCE)of[PEVIM]Cl modified CsPbI_(2)Br device is obviously enhanced from 12.49% to 14.19% with an improved open-circuit voltage of 1.160 V.Moreover,the non-encapsulated device presents excellent thermal stability,still maintaining 91%PCE when heated at 85℃ in nitrogen atmosphere for 360 h.Meanwhile,the non-encapsulated device degrades only 11% PCE after stored at 50% relative humidity for 960 h.This simple and efficient approach provides a promising direction to fabricate high-efficiency and stable inorganic perovskite devices.
基金
This research is supported by the Key Research and Development Program from Shaanxi Province,China(2020GXLH-Z-025)
the Shaanxi International Cooperation Project,China(2020KWZ-018)
the Fundamental Research Funds for the Central Universities,China(3102019ghxm003,3102019JC005,3102019ghjd001).
