Investigation of Inverted Perovskite Solar Cells for Viscosity of PEDOT:PSS Solution

In this paper, we demonstrate that the inverted CH3NH3PbI3 (perovskite) solar cells (PSCs) based on fullerene (C60) as an acceptor is fabricated by applying an improved poly(3,4-ethlyenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) solution as a hole transport layer (HTL). The power conversion efficiency (PCE) of inverted PSCs is increased by 37.5% with stable values of open-circuit voltage (VOC) and fill factor (FF) because we enhance the viscosity of the PEDOT:PSS solution, indicating the perfect effect on both external quantum efficiency (EQE) and surface grain size. The characteristics of the PEDOT:PSS solution, which is being improved through facile methods of obtaining excellent growth of PEDOT:PSS thin film, have a considerable impact on carrier transport. A series of further processing fabrications, including reliable and feasible heating and stirring techniques before the formation of the PEDOT:PSS thin film via spin-coating, not only evaporate the excess moisture but also obviously increase the conductivity. The raised collection of holes become the reason for the enhanced PCE of 3.0%—therefore, the stable performance of FF and VOC are attributed to lower series resistance of devices and the high-quality film crystallization of perovskite and organic acceptors, respectively.