Improved Performance and Reproducibility of Perovskite Solar Cells by Well-Soluble Tris(pentafluorophenyl)borane as a p-Type Dopant

In this work, well-suluble tris-(pentafltiotophenyl)borane (BCF) is introduced for the first time into 2,2',7,7'-tetrakis(N,N'-di-p-methoxyphenylarnine)9,9'-spirobifluorene (Spiro-OMeTAD) as a p-dopant. The conductivity of spiro-OMeTAD films is dramatically enhanced. When the BCF-doped spiro-OMeTAD film is used-as a hole transport layer (HTL) in perovskite solar cells (PSCs),nearly double increase in power conversion efficiericy (PCE)-is obtained compared to that of the PSCS based on a pristine spiro-OMeTAD HTL. By the introduction of lithium bis(trifluorom-ethanesulfonyl)imide Wand 4-tert-blitylpridine into the BCP-doped spiro-OMeTAD,film, the conductivity of spito-OMeTAD film can be further enhanced, and an optimum PCE of 14.65% is obtained., In addition, the average efficiency of the device and the reproducibility of BCF-based PSCs are better than those of FK2Q9-based PSCs. The working mechanisnLdf the BCF-doping effect on spiro-OMeTAD is studiedin,detait The strong electron-accepting ability, excellent solubility in common organic solvents; and the low cost make BCF a,very attractive p-type dopant for spiro-QMeTAD..