title: Femtosecond excitonic relaxation dynamics of perovskite on mesoporous films of Al₂O₃ and NiO nanoparticles.
abstract: The excitonic relaxation dynamics of perovskite adsorbed on mesoporous thin films of Al2O3 and NiO upon excitation at 450 nm were investigated with femtosecond optical gating of photoluminescence (PL) via up-conversion. The temporal profiles of emission observed in spectral region 670-810 nm were described satisfactorily with a composite consecutive kinetic model and three transient components representing one hot and two cold excitonic relaxations. All observed relaxation dynamics depend on the emission wavelength, showing a systematic time-amplitude correlation for all three components. When the NiO film was employed, we observed an extent of relaxation proceeding through the non-emissive surface state larger than through the direct electronic relaxation channel, which quenches the PL intensity more effectively than on the Al2O3 film. We conclude that perovskite is an effective hole carrier in a p-type electrode for NiO-based perovskite solar cells showing great performance.
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 300 (Taiwan).
authors.forename: Hung-Yu
authors.initials: HY
authors.lastname: Hsu
authors.forename: Chi-Yung
authors.initials: CY
authors.lastname: Wang
authors.forename: Amir
authors.initials: A
authors.lastname: Fathi
authors.forename: Jia-Wei
authors.initials: JW
authors.lastname: Shiu
authors.forename: Chih-Chun
authors.initials: CC
authors.lastname: Chung
authors.forename: Po-Shen
authors.initials: PS
authors.lastname: Shen
authors.forename: Tzung-Fang
authors.initials: TF
authors.lastname: Guo
authors.forename: Peter
authors.initials: P
authors.lastname: Chen
authors.forename: Yuan-Pern
authors.initials: YP
authors.lastname: Lee
authors.forename: Eric Wei-Guang
authors.initials: EW
authors.lastname: Diau
keywords: exciton relaxation; femtochemistry; kinetics; perovskite; solar cells