Low Temperature‐Processed Stable and Efficient Carbon‐Based CsPbI2Br Planar Perovskite Solar Cells by In Situ Passivating Grain Boundary and Trap Density

Improvement in stability and an economical processing technique are the main aspects of the commercialization of perovskite solar cells (PSCs). In this study, a 425 nm‐thick CsPbI 2 Br film with a high crystalline, smooth, and uniform surface morphology is obtained by Pb(SCN) 2 passivating the grain boundaries under low temperature (150 °C). The results of a series of electrochemical analyses, including space‐charge‐limited‐current (SCLC), open‐circuit voltage decay (OCVD), electrical impedance spectroscopy (EIS), intensity‐modulated photocurrent spectroscopy (IMPS), and intensity‐modulated photovoltage spectroscopy (IMVS), demonstrate that the trap density of the CsPbI 2 Br film is greatly reduced with Pb(SCN) 2 , which effectively inhibits the interface recombination and promotes charge transport in CsPbI 2 Br PSC. Efficiencies of 12.22% and 10.44% are achieved for low‐temperature‐processed CsPbI 2 Br planar‐architecture PSCs with ITO/SnO 2 /CsPbI 2 Br/ poly(3‐hexylthiophene) (P3HT)/Ag and ITO/SnO 2 /CsPbI 2 Br/carbon, respectively. This low‐cost, high‐efficiency carbon‐based inorganic PSC shows potential industrial application, especially for tandem solar cells.