Excellent intrinsic long-term thermal stability of co-evaporated MAPbI 3 solar cells at 85° C

Thermal stability is a critical criterion for assessing the long-term stability of perovskite solar cells (PSCs). Here, it is shown that un-encapsulated co-evaporated MAPbI(3) (TE_MAPbI(3)) PSCs demonstrate remarkable thermal stability even in an n-i-p structure that employs Spiro-OMeTAD as hole transport material (HTM). TE_MAPbI(3) PSCs maintain over approximate to 95% and approximate to 80% of their initial power conversion efficiency (PCE) after 1000 and 3600 h respectively under continuous thermal aging at 85 degrees C. TE_MAPbI(3) PSCs demonstrate remarkable structural robustness, absence of pinholes, or significant variation in grain sizes, and intact interfaces with the HTM, upon prolonged thermal aging. Here, the main factors driving TE_MAPbI(3) stability are assessed. It is demonstrated that the excellent TE_MAPbI(3) thermal stability is related to the perovskite growth process leading to a compact and almost strain-stress-free film. On the other hand, un-encapsulated PSCs with the same architecture, but incorporating solution-processed MAPbI(3) or Cs-0.05(MA(0.17)FA(0.83))(0.95)Pb(I0.83Br0.17)(3) as active layers, show a complete PCE degradation after 500 h under the same thermal aging condition. These results highlight that the control of the perovskite growth process can substantially enhance the PSCs thermal stability, besides the chemical composition. The TE_MAPbI(3) impressive long-term thermal stability features the potential for field-operating conditions.