Controllable Multistep Preparation Method for High-Efficiency Perovskite Solar Cells with Low Annealing Temperature in Glove Box

摘要

Perovskite solar cells (PeSCs) fabricated by a two-step method have achieved high power conversion efficiency (PCE). Although two-step fabrication makes the formation of perovskite films much easier to control, the too fast reaction between the lead source (such as PbI2) and halogenated organic/inorganic cation (such as formamidinium iodide [FAI]) during the high-temperature (approximate to 150 degrees C for FAPbI(3)) annealing hinders further reaction progress, leaving a large amount of unreacted lead source. This annealing in air is a mandatory step to achieve high-quality perovskite films and then high-efficiency devices with the aid of moisture, which is detrimental to device stability. Herein, a multistep preparation procedure (recoating FA(0.9)MA(0.1)I solution) is proposed to obtain a well-defined perovskite film with large crystal domain size (approximate to several micrometers) and reduced grain boundary at low annealing temperature without the help of moisture (i.e., 60 degrees C in glove box). As a result, a device with high PCE up to 19.301% is achieved using the multistep prepared perovskite film. The high-quality perovskite film is attributed to the dissolution-recrystallization process during the repeated FA(0.9)MA(0.1)I coating procedure. The capability of this multistep method is further demonstrated in fabricating high-performance devices (PCE of 17.762%) without the annealing procedure.