title: Thermal assisted oxygen annealing for high efficiency planar CH₃NH₃PbI₃ perovskite solar cells.
abstract: We report investigations on the influences of post-deposition treatments on the performance of solution-processed methylammonium lead triiodide (CH₃NH₃PbI₃)-based planar solar cells. The prepared films were stored in pure N₂ at room temperature or annealed in pure O₂ at room temperature, 45°C, 65°C and 85°C for 12 hours prior to the deposition of the metal electrodes. It is found that annealing in O₂ leads to substantial increase in the power conversion efficiencies (PCEs) of the devices. Furthermore, strong dependence on the annealing temperature for the PCEs of the devices suggests that a thermally activated process may underlie the observed phenomenon. It is believed that the annealing process may facilitate the diffusion of O₂ into the spiro-MeOTAD for inducing p-doping of the hole transport material. Furthermore, the process can result in lowering the localized state density at the grain boundaries as well as the bulk of perovskite. Utilizing thermal assisted O₂ annealing, high efficiency devices with good reproducibility were attained. A PCE of 15.4% with an open circuit voltage (VOC) 1.04 V, short circuit current density (JSC) 23 mA/cm(2), and fill factor 0.64 had been achieved for our champion device.
authors.affiliation: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong SAR.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Ren
authors.affiliation: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong SAR.
authors.forename: Annie
authors.initials: A
authors.lastname: Ng
authors.affiliation: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong SAR.
authors.forename: Qian
authors.initials: Q
authors.lastname: Shen
authors.affiliation: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong SAR.
authors.forename: Huseyin Cem
authors.initials: HC
authors.lastname: Gokkaya
authors.affiliation: Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong SAR.
authors.forename: Jingchuan
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong SAR.
authors.forename: Lijun
authors.initials: L
authors.lastname: Yang
authors.affiliation: Department of Physics, The University of Hong Kong, Pokfulam, Hong Kong SAR.
authors.forename: Wai-Kin
authors.initials: WK
authors.lastname: Yiu
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong SAR.
authors.forename: Gongxun
authors.initials: G
authors.lastname: Bai
authors.affiliation: Department of Physics, The University of Hong Kong, Pokfulam, Hong Kong SAR.
authors.forename: Aleksandra B
authors.initials: AB
authors.lastname: Djurišić
authors.affiliation: Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong SAR.
authors.forename: Wallace Woon-fong
authors.initials: WW
authors.lastname: Leung
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong SAR.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Hao
authors.affiliation: Department of Chemistry, The University of Hong Kong, Pokfulam, Hong Kong SAR.
authors.forename: Wai Kin
authors.initials: WK
authors.lastname: Chan
authors.affiliation: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong SAR.
authors.forename: Charles
authors.initials: C
authors.lastname: Surya