title: Supersonically Spray-Coated Colloidal Quantum Dot Ink Solar Cells.
abstract: Controlling the thickness of quantum dot (QD) films is difficult using existing film formation techniques, which employ pre-ligand-exchanged PbS QD inks, because of several issues: 1) poor colloidal stability, 2) use of high-boiling-point solvents for QD dispersion, and 3) limitations associated with one-step deposition. Herein, we suggest a new protocol for QD film deposition using electrical double-layered PbS QD inks, prepared by solution-phase ligand exchange using methyl ammonium lead iodide (MAPbI3). The films are deposited by the supersonic spraying technique, which facilitates the rapid evaporation of the solvent and the subsequent deposition of the PbS QD ink without requiring a post-deposition annealing treatment for solvent removal. The film thickness could be readily controlled by varying the number of spraying sweeps made across the substrate. This spray deposition process yields high-quality n-type QD films quickly (within 1 min) while minimizing the amount of the PbS QD ink used to less than 5 mg for one device (300-nm-thick absorbing layer, 2.5 × 2.5 cm2). Further, the formation of an additional p-layer by treatment with mercaptopropionic acid allows for facile hole extraction from the QD films, resulting in a power conversion efficiency of 3.7% under 1.5 AM illumination.
authors.affiliation: Nano-Mechanical Systems Research Division, Korea institute of Machinery and Materials (KIMM), Daejeon, 34103, Korea.|Korea University of Science and Technology (UST), Daejeon, 34113, Korea.
authors.forename: Hyekyoung
authors.initials: H
authors.lastname: Choi
authors.affiliation: School of Mechanical Engineering, Korea University, Seoul, 02841, Korea.
authors.forename: Jong-Gun
authors.initials: JG
authors.lastname: Lee
authors.affiliation: Nano-Mechanical Systems Research Division, Korea institute of Machinery and Materials (KIMM), Daejeon, 34103, Korea.
authors.forename: Xuan Dung
authors.initials: XD
authors.lastname: Mai
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado, 80401, United States.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Beard
authors.affiliation: School of Mechanical Engineering, Korea University, Seoul, 02841, Korea. skyoon@korea.ac.kr.
authors.forename: Sam S
authors.initials: SS
authors.lastname: Yoon
authors.affiliation: Nano-Mechanical Systems Research Division, Korea institute of Machinery and Materials (KIMM), Daejeon, 34103, Korea. sjeong@kimm.re.kr.|Korea University of Science and Technology (UST), Daejeon, 34113, Korea. sjeong@kimm.re.kr.
authors.forename: Sohee
authors.identifier: http://orcid.org/0000-0002-9863-1374
authors.initials: S
authors.lastname: Jeong