Lead-less mesoscopic perovskite solar cells with enhanced photovoltaic performance by strontium chloride substitution

The substitution of toxic lead (Pb) in efficient perovskite solar cells (PSCs) is a key problem for commercialization. In this paper, strontium chloride (SrCl 2 )-doped lead-less PSCs were constructed successfully, and the effect of Sr substitution on the perovskite film formation and its photovoltaic property was investigated in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible absorption, time-resolved photoluminescence (TRPL), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) analyses. It is demonstrated that the introduction of Sr substitution changes the chemical composition of PbI 2 precursors and reduces the excess PbI 2 in the perovskite films. A 10 mol% Sr substitution in the PbI 2 precursor solution can increase the absorbance of the resultant perovskite film and enhance the electron extraction at the “perovskite/TiO 2 ” interface, thus increasing the device's short-circuit current density ( J sc ) from 17.41 mA cm -2 to 19.45 mA cm -2 . At the same time, Sr substitution can reduce the charge combination in the PSC, which allows the PSC to obtain a higher open-circuit voltage ( V oc ) of 1.08 V and fill factor (FF) of 0.74. Finally, the PSC prepared with 10 mol% Sr substitution exhibits a considerable power conversion efficiency (PCE) of 15.64%, showing an improvement of 18.9% compared to that of the pristine device.