THE ROLE OF Br AS DOPANT ON THE STRUCTURAL AND CHARGE TRANSPORT PROPERTIES IN CH3NH3PbI3-x-yBrxCly MIXED-HALIDE PEROVSKITE FOR HYBRID SOLAR CELLS

A series of CH3NH3PbI3-x-yBrxCly mixed-halide perovskite were fabricated as light harvesters for organic-inorganic planar heterojunction perovskite solar cells (PSCs). This paper aimed at investigating the morphology and structural properties of Br doped mixed-halide perovskites and the influence on the corresponding photovoltaic performances. We found that Br incorporation in an I/Cl-based structure dramatically improved the charge transport within the perovskite layer. The average efficiency of the planar device was 13.6% with a minimal standard deviation of +/- 1.53% and best efficiency as high as 15.13% was achieved. Moreover, the device showed superior stability over 20 days with little degradation <9% when stored under ambient conditions, indicating the outstanding performances of planar heterojunction solar cells based on this material. The results highlight the crucial role of the Br doping on the performance of the PSCs and pave the way for further progress on this field.