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Small: molecular ligands regulate the lattice orientation and photovoltaic properties of Dion Jacobson perovskite

wallpapers News 2020-12-10

Professor xu Jianbin Lu Xinhui Professor Yan Keyou of South China University of technology reported for the first time that efficient stable Dion Jacobson (DJ) phase two-dimensional perovskite solar cells with (CHDA) ma3pb4i13 (n = 4) component can reach 15% by using trans-14-cyclohexanediamine (CHDA) as bidentate lig adjusting the two-dimensional layered orientation. The effects of the structure of CHDA ligs on the crystallinity orientation phase stability of 2D perovskite films were systematically studied using 16-diaminohexane (HDA) pea as controls. The main results are as follows:

(1) lig structure can affect the crystallization process. Fresh CHDA samples without annealing show several small peaks at low angles indicating the existence of mesophase. At 100 ° C they are very stable in the first 5 seconds then transform into (111) oriented 2D phase. The intensity of (111) peak (14.2 ° increases gradually with heating showing directional growth. As a contrast the crystallization kinetics of HDA samples are different. The fresh HDA samples without annealing also have unstable mesophase but the lattice orientation of transformed 2D perovskite is not obvious. The XRD double peak is observed at about 14 ° during annealing which indicates that HDA 2D perovskite exhibits poor phase competition during the transformation process leading to poor crystallinity. The crystal orientation of

(2) is special. Giwaxs pattern indicates that the 2D perovskite of CHDA film has a spontaneous tilt orientation which is the first reported new orientation. The 2D slice orientation of CHDA film makes its (111) plane tilt 45 ° relative to the substrate which is very different from the vertical substrate growth of 2D layered structure reported by other groups. The charge transfer in the novel tilted array is also effective the effective contact area of the interface increases which is conducive to the charge extraction. The device performance EQE measurement verify this. The (CHDA) ma3pb4i13 solar cell (n = 4) with inclined arrangement has an efficiency of 15.01% which is one of the highest efficiency of the few layer DJ phase (n < 5) perovskite solar cell. The stability of

(3) devices is improved. Humidity stability test shows that the efficiency of the unsealed CHDA equipment can maintain 94.7% in 1248 hours in 50-60% RH dark cabinet while that of the HDA equipment can only maintain 41.3% in 192 hours. The stability of (CHDA) ma3pb4i13 (n = 4) device is better. The device can maintain 74.4% efficiency of 68 hours at 70 ° C while its isomer HDA device can only maintain 54.9% efficiency under the same conditions. This indicates that the ring configuration of CHDA lig can support the stable 2D perovskite structure more than the linear configuration of HDA lig. The first author of the paper

is Dr. Han Wang who studied for a doctorate in the Department of electronic engineering of the Chinese University of Hong Kong from September 2016 to August 2020. His tutors are Prof. Xu Jianbin Prof. Yan Keyou. At present he is engaged in industry university research related work in the Hong Kong Institute of Applied Science technology. This study

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