title: Controllable Sequential Deposition of Planar CH₃NH₃PbI₃ Perovskite Films via Adjustable Volume Expansion.
abstract: We demonstrate a facile morphology-controllable sequential deposition of planar CH3NH3PbI3 (MAPbI3) film by using a novel volume-expansion-adjustable PbI2·xMAI (x: 0.1-0.3) precursor film to replace pure PbI2. The use of additive MAI during the first step of deposition leads to the reduced crystallinity of PbI2 and the pre-expansion of PbI2 into PbI2·xMAI with adjustable morphology, which result in about 10-fold faster formation of planar MAPbI3 film (without PbI2 residue) and thus minimize the negative impact of the solvent isopropanol on perovskites during the MAI intercalation/conversion step. The best efficiency obtained for a planar perovskite solar cell based on PbI2·0.15MAI is 17.22% (under one sun illumination), which is consistent with the stabilized maximum power output at an efficiency of 16.9%.
authors.affiliation: †School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
authors.forename: Taiyang
authors.initials: T
authors.lastname: Zhang
authors.affiliation: ‡Chemistry and Nanoscience Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States.
authors.forename: Mengjin
authors.initials: M
authors.lastname: Yang
authors.affiliation: †School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
authors.forename: Yixin
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: ‡Chemistry and Nanoscience Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhu
keywords: Perovskite; sequential deposition; solar cells; volume expansion