Antisolvent with an Ultrawide Processing Window for the One‐Step Fabrication of Efficient and Large‐Area Perovskite Solar Cells

Abstract

Among the above methods, the most common strategy is the one-step spincoating deposition assisted by an antisolvent, which is an easy and efficient approach to obtain dense and highly crystalline perovskite thin film. Three organic solvents-chlorobenzene (CB), [4b] methylbenzene (toluene), [4a] and diethyl ether (ether) [4c] -are the favorite antisolvents for this method. Efficient PSCs with PCE over 20% have been frequently obtained by using these antisolvents, [6] through the one-step spin-coating method.Three dominant parameters related to the one-step spin-coating process are: 1) the ratio between dimethylformamide (DMF):dimethyl sulfoxide (DMSO) in the perovskite precursor solution, 2) the antisolvent dripping time during the spin procedure, and 3) the antisolvent volume used for each coating process as depicted in Figure 1a. However, the current antisolvents mentioned above usually have very narrow and various operating windows. For instance, from the point of view of DMF/DMSO ratio, the proper value for CB is 4:1, [7] toluene is 7:3, [4a] while ether is 9:1. [4c] Meanwhile, the dripped antisolvent volume for each antisolvent is also different from case to case: 0.1 mL for CB, 0.5-1.0 mL for toluene, and 0.5 mL for ether. [4a,c,6a,7] This actuality means that only skillful experimenters can handle the spin-coating tricks and thus fabricate PCEs with high efficiency, which limits the development of the PSCs.Herein, we would like to introduce anisole as an antisolvent, with ultrawide processing window for the one-step fabrication of efficient and large-area PSCs. Using the anisole as antisolvent, there is no need to make any significant effort to obtain optimized conditions for the fabrication of high-quality perovskite films (Figure 1b). By dripping anisole on the spinning perovskite precursor film, it is possible to make dense and crystalline perovskite films as shown in Figure 1c,d. The thickness of the perovskite capping layer is about 450 nm, which is comparable with the perovskite thin films using the other antisolvents with optimized condition. [7,8] Also, the PCEs of PSCs fabricated using anisole are not sensitive to the precursor solution composition and antisolvent dripping parameters. We prepared perovskite thin films Photovoltaic technologies based on perovskite absorber materials have led this optoelectronic field into a brand-new horizon. However, the present antisolvents used in the one-step spin-coating method always encounter problems with the very narrow process window. Herein, anisole is introduced into the one-step spin-coating method, and the technology is developed to fabricate perovskite thin films with ultrawide processing window with a dimethylformamide (DMF):dimethyl sulfoxide (DMSO) ratio varying from 6:4 to 9:1 in the precursor solution, anisole dripping time ranging from 5 to 25 s, and an antisolvent volume varying from 0.1 to 0.9 mL. Perovskite thin films as large as 100 cm 2 are successfully fabricated using this method. Maximum photoelectric conversion efficiencies of 1...

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