- 건국대학교

	Prof. Man-Jong Lee Reported a Novel Doping Technique for Highly Stable and Efficient Planar Perovskite Solar Cells
	관리자		499		2021.01.13

<img alt="" src="ArticleFile.do?id=11810988" /> 
Sub-title: Publication in the one of the best SCI journal paper in the field of APPLIED CHEMISTRY (Journal of Energy Chemistry, top 2.1%, IF: 7.216, ranking: 2/72)
The research team of Professor Man-Jong Lee of the Department of Chemistry at Konkuk University has developed a novel composition engineering technique by doping a stabilizer called acetamidinium bromide (AABr) into the crystal lattices of methyl ammonium lead halide (MAPbI3) single-cation perovskite semiconductors. He achieved a power conversion efficiency of 20.18%. In particular, the stability, which is the weakness of MAPbI3 perovskite based solar cells, has been greatly improved and he has achieved a remarkable result maintaining more than 95% of the initial efficiency even after 1200 hours. Professor Ki Chul Kim’s team of the Division of Chemical Engineering participated in this study using a computational chemical technique. This study was conducted with the support of the Korea Research Foundation's personal research program and the Agency for Defense Development (Future Challenge Project), and was published in the online edition of the Journal of Energy Chemistry on December 31, 2020.
Shortcut:<a href="https://doi.org/10.1016/j.jechem.2020.12.022" target="_blank">https://doi.org/10.1016/j.jechem.2020.12.022</a>
Research overview
The single cation MAPbI3 perovskite semiconductor thin film can be easily fabricated by a solution method, but local separation occurs due to the easy mobilities of the methyl and ammonium groups inside the MAPbI3, leading to a decrease in power conversion efficiencies. Currently, in order to achieve such long-term stability, this research team as well as the world's leading laboratories are focused on a mixed-cationic semiconductors including (FAPbI3)0.95(MAPbBr3)0.05 and Cs0.01FA0.94MA0.05PbI2.85Br0.15 thin films to increase the instability. However, since the various mixed-cationic composite perovskite semiconductors are vulnerable to moisture and require expensive manufacturing facilities such as glove boxes or dry rooms, it is recognized as a major problem for the global commercialization of low-cost perovskite solar cells.
Prof. Man-Jong Lee believes that MAPbI3 single cation perovskite semiconductor thin film can be applied not only to solar cells but also to various devices owing to the advantage of being less sensitive to moisture, if the long-term stability of MAPbI3 can be improved. He focused on the problem of mobile ions in MAPbI3 films. It was concluded that the mobility of the two ions could be limited if the other semiconductor material having a slightly larger size than the ionic radius of the two ions is effectively substituted within the lattices without forming impurities. He selected the substitution of MAPbI3 with acetamidinium bromide (AABr) semiconductor having a similar crystal structure. With the cooperation of Professor Ki Chul Kim's team, it was proved by the density functional theory (DFT), a computational chemical technique, that when AABr is substituted in the MAPbI3 crystal lattice, the formation energy is lower and the substitution is thermodynamically favorable (Figure a-c). In addition, through various experimental techniques, the physicochemical properties (Figure d-I) of the stabilized MAPbI3 semiconductor thin films (MA1-xAAxPbI3-xBrx, x = 1 mol%, 3 mol%, 5 mol%, or 7 mol%) were investigated through various experimental techniques. Professor Lee comments “This work is a meaningful study that presents a new possibility of MAPbI3, and is significant in that it achieved high efficiency and remarkable stability by stabilizing the MAPbI3 structure with a semiconductive substance called AABr for the first time”. <img alt="" src="ArticleFile.do?id=11810986" width="633" height="463" /> 
Figure (a) Schematic of the process for the incorporation of AABr into the MAPbI3 lattices using compositional engineering. Supercell structures for (b) AABr doped MAPbI3 (ABP) and (c) pristine MAPbI3 (PMP). (d and e) Surface SEM images of PMP and ABP, (f) cross-sectional SEM image of device architecture, (g) J-V curves of champion solar cells based on ABP and PMP, (h) EQEs of champion solar based on ABP and PMP, (i) operational stability results for the two cells (without encapsulation) under 40% humidity and 25 °C in ambient air.

	Prof. Man-Jong Lee reported a novel doping technique for highly stable and efficient planar perovskite solar cells.png (1,230,093) image.PNG (148,544)
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