J-V characteristic of perovskite solar cells using lead(II) thiocyanate doped-methylammonium lead iodide (MAPbI₃) as active material

Perovskite solar cells based on methylammonium iodide (MAPbI₃) as active material have been intensively investigated for low cost and high power conversion efficiency (PCE). Todays, the PCE beyond 20% have been obtained using different structures of solar cells. However, there are still many problems needed to be solved prior to mass production and commercialization, in particular the stability of solar cells. The PCE decreases significantly in high humidity due to the decomposition of organic methylammonium iodide with water vapor from air-humid into lead iodide. Many researchers are now paying a lot of attentions to improve the stability of perovskite solar cells, including device structures, interfaces engineering and materials engineering. Recently, perovskite solar cell based on methylammonium lead(II) thiocyanate [MA(PbSCN)₂] improved the humidity-stability of solar cells, due to higher binding energy of thiocyanate (SCN) ions to Pb ions as than that of iodide (I) ions to Pb ions. However, the PCE is lower than that of commonly used MAPbI₃ solar cells, because the large bandgap leads to low light absorption. In this work, we present our recent study on J-V characteristic of solar cells using lead(II) thiocyanate Pb(SCN)₂ doped lead(II) iodide as active materials of perovskite solar cells. We prepared perovskite films using two-step spin-coating method. We used two different structures of solar cells, mesoporous device and inverted planar structure. The best PCE of solar cells is 7% obtained with inverted planar structure. The mesoporous device structure shows lower performance than that of inverted planar structure, which is due to poor quality of electron transport layer, both titanium dioxide (TiO₂) both blocking and mesoporous layers.