Synergetic Effect of Chloride Doping and CH NH PbCl on CH NH PbI Cl Perovskite-Based Solar Cells.

The chloride-doped CH NH PbI Cl perovskite has attracted great attention owing to clear performance enhancement by using a Cl additive and by the controversial arguments on Cl function and the mechanism behind it. Herein, a series of CH NH PbI Cl perovskites with various Cl content was prepared through a gas/solid reaction between CH NH gas and HPbI Cl (x=0-1). The small amount of Cl doping in CH NH PbI Cl (x=0.05) could lead to band gap broadening and significantly increase the perovskite grain size, and the phase-pure CH NH PbI Cl perovskites exhibited up to 17.44 % efficiency. For Cl contents higher than 0.1 (x>0.1), CH NH PbCl formed and coexisted with CH NH PbI Cl , and CH NH PbCl could help to improve the thermal stability of CH NH PbI Cl . However, the excessive co-existing wide-band-gap CH NH PbCl perovskites would inhibit the electron transfer and lead to a deterioration of photovoltaic performance.