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Considering the evaporation of solvents during fabrication of perovskite films, the organic ambience will present a significant influence on the morphologies and properties of perovskite films. To clarify this issue, various ambiences of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and chlorobenzene (CBZ) are introduced during fabrication of perovskite films by two-step sequential deposition method. The results reveal that an ambient CBZ atmosphere is favorable to control the nucleation and growth of CH3NH3PbI3 grains while the others present a negative effect. The statistical results show that the average efficiencies of perovskite solar cells processed in an ambient CBZ atmosphere can be significantly improved by a relatively average value of 35%, compared with those processed under air. The efficiency of the best perovskite solar cells can be improved from 10.65% to 14.55% by introducing this ambience engineering technology. The CH3NH3PbI3 film with large-size grains produced in an ambient CBZ atmosphere can effectively reduce the density of grain boundaries, and then the recombination centers for photoinduced carriers. Therefore, a higher short-circuit current density is achieved, which makes main contribution to the improvement in efficiency. These results provide vital progress toward understanding the role of ambience in the realization of highly efficient perovskite solar cells.
Huang et al. (2016) studied this question.