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 S cm for the pristine spiro-OMeTAD to 1.1×10 S cm at 5 % BPO doping and to 2.4×10 S cm at 15 % BPO doping, which considerably outperform the conductivity of 4.62×10 S cm 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 NH PbI 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.

Doping strategies for small molecule organic hole-transport materials: impacts on perovskite solar cell performance and stability

“…An IrCp*Cl(PyPyz)[TFSI]-based doping system153 showed superior stability (96% PCE retention over 3 months in the dark in ambient conditions) over control devices (Table 1, entry 5). Benzoyl peroxide154 and iron-based complexes155,156 also successfully dope spiro-OMeTAD with LiTFSI co-dopant for efficiency improvements (Table 1, entries 19, 23, and 24 respectively). A lithium-ion endohedral fullerene (Li + @C 60 ) was also recently reported (Table 1, entry 25) 157.…”

Efficiencyvs.stability: dopant-free hole transporting materials towards stabilized perovskite solar cells

“…Traditionally, the hole transporting layer of PSCs is heavily doped with p-type dopants to provide the necessary electrical conductivity for the state-of-the-art spiro-OMeTAD and other wide bandgap HTMs. Numerous p-type dopants have been developed and realized including 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ),73–75 benzoyl peroxide,76 and copper( ii )77 and cobalt( iii )78,79 complexes (Fig. 5).…”

Doping molecular organic semiconductors by diffusion from the vapor phase

“…This value is two orders of magnitude higher than the conductivity reached by typical LiTFSI doping 14 and similar to the 0.024 S cm À1 reported for LiTFSI and benzoyl peroxide doping. 28 Estimating with s = qpm, we found that the electrical mobility may decrease but remains on the order of 10 À4 cm 2 V À1 s À1 . (see Fig.…”