Enhanced stability and efficiency of Sn containing perovskite solar cell with SnCl₂ and SnI₂ precursors

Presence of toxic Pb and device stability are the main issues with perovskite solar cell. For Pb replacement, most likely substitute is Sn, which is a metal of group 14 (like Pb). Thus, in the present study, the amount of Pb is reduced and replaced by Sn. To achieve the replacement, use of SnCl₂ is explored in addition to generally used precursor (SnI₂), as the source of Sn. Molar ratio of PbI₂:SnCl₂/SnI₂ is varied to get optimum performance of perovskite solar cell. Pt–FTO counter electrode is used in addition to spiro-MeTAD (as hole transport material). The power conversion efficiency of solar cells containing 2:2 molar ratio of PbI₂:SnCl₂ was enhanced to 10.10%, and PbI₂:/SnI₂ was enhanced to 10.61%. Without Sn addition (CH₃NH₃PbI₃) the efficiency was only 7.39%. The clear enhancement of 37% (SnCl₂) and 43% (SnI₂) is highly encouraging, as it leads to less toxic and highly efficient solar cells at the same time. In addition, the percentage loss in power conversion efficiency of device prepared with SnCl₂ (CH₃NH₃Pb_0.5Sn_0.5ICl₂) was also superior (10 days).