title: Carbon Quantum Dots/TiOxElectron Transport Layer Boosts Efficiency of Planar Heterojunction Perovskite Solar Cells to 19.
abstract: In planar n-i-p heterojunction perovskite solar cells, the electron transport layer (ETL) plays important roles in charge extraction and determine the morphology of the perovskite film. Here, we report a solution-processed carbon quantum dots (CQDs)/TiO2composite that has negligible absorption in the visible spectral range, a very attractive feature for perovskite solar cells. Using this novel CQDs/TiO2ETL in conjunction with a planar n-i-p heterojunction, we achieved an unprecedented efficiency of ∼19% under standard illumination test conditions. It was found that a CQDs/TiO2combination increases both the open circuit voltage and short-circuits current density as compared to using TiO2alone. Various advanced spectroscopic characterizations including ultrafast spectroscopy, ultraviolet photoelectron spectroscopy, and electronic impedance spectroscopy elucidate that the CQDs increases the electronic coupling between the CH3NH3PbI3-xClxand TiO2ETL interface as well as energy levers that contribute to electron extraction.
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , 1037 Luoyu Road, Wuhan 430074, Hubei, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , 1037 Luoyu Road, Wuhan 430074, Hubei, China.
authors.forename: Weina
authors.initials: W
authors.lastname: Shi
authors.affiliation: Department of Materials Science and Engineering, University of California Los Angeles , 405 Hilgard Avenue, Los Angeles, California 90095-9000, United States.
authors.forename: Wenchao
authors.initials: W
authors.lastname: Huang
authors.affiliation: Department of Materials Science and Engineering, University of California Los Angeles , 405 Hilgard Avenue, Los Angeles, California 90095-9000, United States.|Advanced Optoelectronic Technology Center, National Cheng Kung University , No. 1, University Road, East District, Tainan City 70101, Taiwan.
authors.forename: En-Ping
authors.initials: EP
authors.lastname: Yao
authors.affiliation: Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology , 1037 Luoyu Road, Wuhan 430074, Hubei, China.
authors.forename: Junbo
authors.initials: J
authors.lastname: Han
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , 1037 Luoyu Road, Wuhan 430074, Hubei, China.
authors.forename: Zhifan
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , 1037 Luoyu Road, Wuhan 430074, Hubei, China.
authors.forename: Shuangshuang
authors.initials: S
authors.lastname: Liu
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , 1037 Luoyu Road, Wuhan 430074, Hubei, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , 1037 Luoyu Road, Wuhan 430074, Hubei, China.
authors.forename: Mingkui
authors.identifier: 0000-0002-4516-2500
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Materials Science and Engineering, University of California Los Angeles , 405 Hilgard Avenue, Los Angeles, California 90095-9000, United States.
authors.forename: Yang
authors.identifier: 0000-0001-8833-7641
authors.initials: Y
authors.lastname: Yang
keywords: Perovskite; electron transport; heterojunction; quantum dots; solar cell