Overcoming Perovskite Corrosion and De-Doping Through Chemical Binding of Halogen Bonds Toward Efficient and Stable Perovskite Solar Cells

Abstract

Highlights

Chemical binding of 4-tert-butylpyridine (TBP) is realized through halogen bonds.

TBP-induced perovskite decomposition and spiro-OMeTAD de-doping are suppressed.

Modified perovskite solar cells achieve greatly improved efficiency and stability.

4-tert-butylpyridine (TBP) is an indispensable additive for the hole transport layer in highly efficient perovskite solar cells (PSCs), while it can induce corrosion decomposition of perovskites and de-doping effect of spiro-OMeTAD, which present huge challenge for the stability of PSCs. Herein, halogen bonds provided by 1,4-diiodotetrafluorobenzene (1,4-DITFB) are employed to bond with TBP, simultaneously preventing perovskite decomposition and eliminating de-doping effect of oxidized spiro-OMeTAD. Various characterizations have proved strong chemical interaction forms between 1,4-DITFB and TBP. With the incorporation of halogen bonds, perovskite film can maintain initial morphology, crystal structure, and light absorbance; meanwhile, the spiro-OMeTAD film shows a relatively stable conductivity with good charge transport property. Accordingly, the device with TBP complex exhibits significantly enhanced stability in N₂ atmosphere or humidity environment. Furthermore, a champion power conversion efficiency of 23.03% is obtained since perovskite is no longer damaged by TBP during device preparation. This strategy overcomes the shortcomings of TBP in n-i-p PSCs community and enhances the application potential of spiro-OMeTAD in fabricating efficient and stable PSCs.