Sn Perovskite Solar Cells with Tin Oxide Nanoparticle Layer as Hole Transport Layer

Tinperovskite solar cells (Sn-PVK-PVs) are a promisingalternative to lead perovskite solar cells (Pb-PVK-PVs). Poly(3,4-ethylenedioxythiophene) polystyrene sulphonic acid (PEDOT:PSS)is employed as the hole transport layer (HTL). However, the matterof concern is the damage of the Sn-PVK layer by the acidic propertiesof the PEDOT:PSS. Therefore, PEDOT:PSS-free Sn-PVK-PV is eagerlyawaited. In this paper, the inorganic hole collectors using commerciallyavailable SnO2 nanoparticles (Nano SnO2) arereported. It is well-known that Nano SnO2 works as anelectron transport layer for Pb-PVK-PVs. However, we foundthat the Nano SnO2 surface was reduced to SnOx (x < 2) nanoparticles (abbreviated as P-NanoSnO(x)) when the Nano SnO2 contacted with theSn-PVK layer, and the resulting P-Nano SnOx works effectivelyas the HTL of the Sn-PVK-PVs. The efficiency of 9.77% is reported.Furthermore, P-Nano SnOx devices showed higher stabilityin comparison to PEDOT:PSS devices.