Post-Treatment of Mesoporous Scaffolds for Enhanced Photovoltage of Triple-Mesoscopic Perovskite Solar Cells

Triple-mesoscopic perovskite solar cells (PSCs) based on TiO2/ZrO2/carbon architecture have attracted much attention due to their excellent long-term stability and screen-printing technique-based fabrication process. However, the relatively low open-circuit voltage (V-OC) limits the further improvement of power conversion efficiency (PCE) for triple-mesoscopic PSCs. Herein, 2-phenyl-5-benzimidazole sulfonate-Na to post-treat the triple-mesoscopic structured scaffold is introduced. The conduction band of the mesoporous TiO(2)layer (electron transport layer [ETL]) is significantly shifted up from -4.22 to -4.11 eV, which favors the electron transfer from the perovskite absorber to the ETL. At the same time, the recombination at the interface of ETL/perovskite is effectively suppressed. Correspondingly, theV(OC)and fill factor (FF) of the devices are enhanced without sacrificing the photocurrent density (J(SC)). With optimal post-treatment conditions, the champion device delivers aV(OC)of 1.02 V and an FF of 0.70 withJ(SC)of 23.06 mA cm(-2), showing an overall PCE of 16.51%. After 1000 h continuous operation at the maximum power point under AM1.5G 1 sun illumination, the devices can maintain 91.7% of the initial efficiency. This simple procedure and significant photovoltage enhancement render this method promising for fabricating efficient PSCs based on mesoporous charge transport layers.