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Chapter 11 • Hybrid Organic–Inorganic Metal Halide Perovskite Solar Cells 241
FIGURE 11.5 (A) The photocurrent of the MAPbI 3 solar cells in planar device structure under 1-sun illumination, (B) EQE
of the solar cell with the active layer of MAPbI 3 . Adapted with the permission of Bi C, Wang Q, Shao Y, Yuan Y, Xiao Z,
Huang J. Nonwetting surface-driven high-aspect-ratio crystalline grain growth for efficient hybrid perovskite solar cells.
Nat Commun 2015;6, copyright 2015.
11.4.1 Solvent to Film Optimization
The solvent engineering strategy of using mixed solvents and/or anti-solvents has be-
come an effective but simple technique for realizing favorable perovskite film morphol-
ogy in order to achieve high-performance perovskite solar cells [73,74]. In the perovskite
film fabrication process, the precursor solution is prepared by dissolving in a mixture of
dimethylsulfoxide (dMSO) and γ-butyrolactone (GBL) and the solution is spun coated by
using one-step or two-step approach. dMSO is one of the commonly used solvent due to
its strong coordination with MX 2 to form metal-halide complexes [44,75]. dMSO is not the
only solvent that can produce high quality perovskite film as demonstrated by Wu et al.
[76]. Instead of using dMSO/GBL combination, Kim et al. [77] used a combination of N,N-
dimethylformamide (dMF) and GBL to prepare perovskite film with improved film qual-
ity. In the film fabrication process, application of antisolvent such as toluene is used to
extract excess solvent such as dMSO and dMF for the rapid precipitation of the perovskite
film before significant growth takes place [78]. The incorporation of toluene in film fabri-
cation process produces small-grain and dense perovskite films.