Jung, Kyungeun Lee, Jae-Ho Oh, Kwonwoo Im, Chan Do, Junghwan Kim, Joosun Chae, Weon-Sik Lee, Man-Jong 2024-01-19T21:30:17Z 2024-01-19T21:30:17Z 2021-09-04 2018-12 2211-2855 https://pubs.kist.re.kr/handle/201004/120647 We synthesized uniform FA(x)MA(1-x)PbI(3) perovskite films with a single a phase by a two-step process combined with a dynamically dispensed spin-coating technique. It uses the continuous dropping of precursor solutions with a constant CH3NH3I (MAI)/HC(NH2)(2)I (FAI) concentration enabling the kinetically controlled grain growth. Dynamic coating cycles are also changed to facilitate a cation-exchange process, control the degree of the mutual inter-mixing between formamidinium lead triiodide (FAPbI(3)) and methylammonium lead triiodide (MAPbI(3)) and examine the formation process and properties of the mixed perovskite films formed under the excess MA/FA cation environment, which has not been clarified so far. Notably, without additional solvent washing steps, FA(x)MA(1-x)PbI(3) films are adjustable in composition, pinhole-free, and have various grain sizes depending on the coating cycles. Perovskite solar cells (PSCs) synthesized from FA(x)MA(1-x)PbI(3) films with two cycles of the dynamic spin coating have achieved a maximum power conversion efficiency (PCE) of 18.50% with an average PCE of 17.06 +/- 0.42%, which shows much-improved performance as well as reproducibility compared with 14.79 +/- 1.82% obtained from the conventional static spin-coating method. In addition, we first found mixed FA(x)MA(1-x)PbI(3) perovskites synthesized under an excess cation environment containing local stoichiometric inhomogeneities as well as excess residual cations (C-N and NH3+) acting as recombination traps, which is supported by the calculation of trap densities. English ELSEVIER LEAD IODIDE CH3NH3PBI3 PEROVSKITE MOBILE IONS BASE ADDUCT METHYLAMMONIUM LAYERS TRANSFORMATION TRIHALIDE GROWTH STATE Efficient composition tuning via cation exchange and improved reproducibility of photovoltaic performance in FA(x)MA(1-x)PbI(3) planar heterojunction solar cells fabricated by a two-step dynamic spin-coating process Article 10.1016/j.nanoen.2018.10.023 1 NANO ENERGY, v.54, pp.251 - 263 NANO ENERGY 54 251 263 scie scopus 000450974700028 2-s2.0-85055190327 Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Physics, Applied Chemistry Science & Technology - Other Topics Materials Science Physics Article LEAD IODIDE CH3NH3PBI3 PEROVSKITE MOBILE IONS BASE ADDUCT METHYLAMMONIUM LAYERS TRANSFORMATION TRIHALIDE GROWTH STATE Dynamic spin coating FA(x)MA(1-x)PbI(3) perovskite Cation exchange Planar cells Time-resolved photoluminescence mapping FTIR-imaging mapping