Benzoyl Peroxide as an Efficient Dopant for Spiro‐OMeTAD in Perovskite Solar Cells

Abstract Although organic small molecule spiro‐OMeTAD is widely used as a hole‐transport material in perovskite solar cells, its limited electric conductivity poses a bottleneck in the efficiency improvement of perovskite solar cells. Here, a low‐cost and easy‐fabrication technique is developed to enhance the conductivity and hole‐extraction ability of spiro‐OMeTAD by doping it with commercially available benzoyl peroxide (BPO). The experimental results show that the conductivity increases several orders of magnitude, from 6.2×10 −6 S cm −1 for the pristine spiro‐OMeTAD to 1.1×10 −3 S cm −1 at 5 % BPO doping and to 2.4×10 −2 S cm −1 at 15 % BPO doping, which considerably outperform the conductivity of 4.62×10 −4 S cm −1 for the currently used oxygen‐doped spiro‐OMeTAD. The fluorescence spectra suggest that the BPO‐doped spiro‐OMeTAD–OMeTAD layer is able to efficiently extract holes from CH 3 NH 3 PbI 3 and thus greatly enhances the charge transfer. The BPO‐doped spiro‐OMeTAD is used in the fabrication of perovskite solar cells, which exhibit enhancement in the power conversion efficiency.