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제124회 대한화학회 학술발표회, 총회 및 기기전시회 안내 Structure characterization of (FAPbI3)1-x(MAPbBr3)x thin films (x=0.02, 0.05) incorporated with different additives using x-ray reflection and diffraction

2019년 8월 21일 11시 24분 43초
PHYS.P-154 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
10월 17일 (목요일) 11:00~12:30
Physical Chemistry
저자 및
Ki-Yeon Kim*, In-Hwan Oh, Seungjoo Lee1, Nam Joong Jeon2
Neutron Science Division, Korea Atomic Energy Research Institute, Korea
1Department of Chemistry, Chonnam National University, Korea
2Solar Energy Materials, Korea Research Institute of Chemical Technology, Korea
We have investigated the effect of different additives on thin film structure and morphology of ((formamidinium (FA) or HC(NH2)2)PbI3)1-x((methylammonium (MA) or CH3NH3PbI3)PbBr3)x (x=0.02 or 0.05) thin films using specular x-ray reflection (XRR) and low-angle x-ray diffraction(XRD). 50 nanometer-thick (FAPbI3)1-x(MAPbBr3)x thin films were synthesized by spin-coating on Si substrate with a surface dimension of 1×1 inch2 and three different kinds of additives such as MACl and 5 mol% CsI and 5 mol% RbI were considered. Further details on sample synthesis can be found in reference [1]. Kiessig interference fringe owing to total film thickness in XRR data is clearly observed in MACl-added (FAPbI3)1-x(MAPbBr3)xfilms only, indicating that they are pin-hole free, continuous, and interface/surface roughness is not so rugged over Si substrate. Besides, there exists a very thin layer with a few nanometer thickness between substrate and (FAPbI3)1-x(MAPbBr3)x sublayers for all the samples irrespective of additives. XRR data analysis reveals that this thin layer is likely to be PbI2. Low angle XRD shows that a very strong α-FAPbI3 (100) peak at 2θ=13.9º is observed but δ-FAPbI3 (100) peak at 2θ=11.7(8)º is not in MACl-added (FAPbI3)1-x(MAPbBr3)x films. Meanwhile, both α-FAPbI3 and δ-FAPbI3 are observed and α-FAPbI3 (100) peak intensity is significantly reduced in CsI or both CsI and RbI-added (FAPbI3)1-x(MAPbBr3)x films due to the relatively worse surface morphology. It should be noted that PbI2 (001) phase at 2θ=12.7 º is present for all the samples. Time-dependent XRD data show that α-FAPbI3 peak remains intact even though they has been unencapsulated and exposed to a humid air of relative humidity of around 50%. However, XRR unambiguously exhibits that the interdiffusion between (FAPbI3)1-x(MAPbBr3)x and PbI2(001) sublayers takes place over a period of about one month. We suggest that a combination of XRR and XRD can be effective experimental tools to characterize the structure of the inorganic-organic perovskite thin films. Reference [1] N. J. Jeon, J. H. Noh, W. S. Yang, Y. C. Kim, S. Ryu, J. Seo & S. I. Seok, Compositional engineering of perovskite materials for high-performance solar cells, Nature 517 (2015) 476-480