Self-woven monolayer polyionic mesh to achieve highly efficient and stable inverted perovskite solar cells

Abstract Poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) is widely used in inverted perovskite solar cells due to its simple preparation process, high stability and light transmittance (low refractive index and extinction coefficient). Theoretical studies have shown that a sufficiently thin PEDOT:PSS layer is necessary to guarantee high optical absorption of the devices. However, some limitations of PEDOT:PSS film induced by traditional deposition method, such as thick film, partly unfriendly contact at PEDOT:PSS/perovskite, hamper its progress in the inverted PSCs for a future market success. Here, a namely self-woven deposition method, has been proposed to prepare a pinhole-free monolayer PEDOT:PSS mesh. The Power conversion efficiency (PCE) of an inverted device has been boosted to 19.49 % from 15.31%, once employing this monolayer PEDOT:PSS mesh as hole transport layer, with structure of ITO/PEDOT:PSS/MAPbI3(Cl)/C60/BCP/Ag. The high performance is mainly attributed to more light reach to perovskite layer due to this monolayer polyionic mesh, and is secondarily ascribed to better energy-level alignment and efficient hole extraction. In addition, this monolayer mesh based device exhibits a relatively high operation stability as well as storage stability thanks to the reduction of the unpaired PSS. Particularly, the validity of the self-woven method is confirmed by employing (FASnI3)0.6(MAPbI3)0.4 perovskite as active material in the same scenario, achieving more than 21% PCE.