Exposed the mechanism of lead chloride dopant for high efficiency planar-structure perovskite solar cells

Abstract

Although the PbCl2 has been exploited to improve the performance of perovskite solar cells, the mechanism of enhancement by the introducing PbCl2 is not fully understudied. In present work, we used the PbCl2 as a dopant to improve the perovskite film quality, we found the crystalline and grain size of perovskite film both increased with 10% molar ratio of PbCl2. The in situ time-resolved grazing incidence wide-angle X-ray scattering measurements revealed that more pre-nucleated suspended in the solution when employed the PbCl2 dopant, leading to high crystalline for perovskite film. An incorporation of the space charge limit current, photoluminescence, time-resolved photoluminescence measurements, we uncover the function of PbCl2 in reduced trap density, decreased charge recombination and enhanced carrier lifetime. As a result, the efficiency of planar-structure perovskite solar cells based on PbCl2 enhanced to as high as 19.79% with reduced hysteresis, increased by ∼23% compared to the device without PbCl2 (16.05%). We believe that this work would provide a fundamental prospective for mixed perovskite and promote its application in perovskite photovoltaics.