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Lead-Free Dion-Jacobson Tin Halide Perovskites for Photovoltaics Min Chen, Ming-Gang Ju, Mingyu Hu, Zhenghong Dai, Yue Hu, Yaoguang Rong, Hongwei Han, Xiao Cheng Zeng, Yuanyuan Zhou, and Nitin P Padture ACS Energy Lett., Just Accepted Manuscript • DOI: 10.1021/acsenergylett.8b02051 • Publication Date (Web): 13 Dec 2018 Downloaded from http://pubs.acs.org on December 13, 2018
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ACS Energy Letters
Lead-Free Dion-Jacobson Tin Halide Perovskites for Photovoltaics Min Chen,1 Ming-Gang Ju,2 Mingyu Hu,1 Zhenghong Dai,1 Yue Hu,3,* Yaoguang Rong,3 Hongwei Han,3 Xiao Cheng Zeng,2 Yuanyuan Zhou1,* and Nitin P. Padture1,* 1School
of Engineering, Brown University, Providence, Rhode Island 02912, USA
2Department
of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA
3Wuhan
National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China For: ACS Energy Letters (Energy Express) Manuscript No. nz-2018-02051d Abstract Synthesis and photovoltaic performance of low-dimensional Dion-Jacobson Sn(II)-based halide perovskites are reported here for the first time, leading to the emergence of a new class of promising lead-free perovskites for solar cells and other applications. Graphical Abstract
Perovskite solar cells (PSCs) based on Pb-containing organic-inorganic halide perovskites have now achieved record power conversion efficiency (PCE) of 23.3% within a relatively short period of time.(1-2) However, the toxicity of Pb is likely to be a serious hurdle in the path towards future commercialization of PSCs.(3-4) Several elements such as Sn(II),(5) Bi(III),(6) Sb(III),(7) and Ti(IV) (8-9) with relatively lower toxicity are being considered for replacing Pb(II) in PSCs. To date, Sn-based PSCs have shown the most promising PCE.(5) However, it has been argued that Sn-vacancies form easily in Sn(II)-based perovskites, which results in metallic conductivity.(10) Furthermore, Sn(II) readily oxidizes to Sn(IV), leading to poor air-stability, inadequate optoelectronic properties, and, thus, lower device PCE.(11) In order to overcome these issues, we report the synthesis of a new-type Dion-Jacobson (DJ) Sn(II)-based low-dimensional perovskite — (4AMP)(FA)n-1SnnI3n+1 — and demonstrate its first use in PSCs with promising PCE of over 4%. Here FA is formamidium (HC(NH2)2+), 4AMP is 4-(aminomethyl)piperidinium, and n is the number of octahedra layers in the perovskite-like stack. The discovery of this new lead-free
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perovskites is inspired by the previous first report of lead-based DJ halide perovskites by Mao et al.(12)
Figure 1. DJ Sn-based halide perovskite (4AMP)(FA)n-1SnnI3n+1 (n=4): (a) schematic crystal structure, (b) experimental XRD pattern (powder) with Rietveld refinement (Bragg positions and residual), showing a possible crystal structure with space group Ia and lattice parameters: a = 8.978 Å, b = 8.966 Å, c = 59.656 Å, α = ϒ =90˚, β = 91.109˚. (d) absorption and steady-state PL spectra (powder), and (e) time-resolved PL spectra (powder).
The DJ Sn(II)-based halide perovskite structure of (4AMP)(FA)n-1SnnI3n+1 is illustrated in Figure 1a. It features aligned divalent (+2) interlayer organic spacers, instead of the staggered interlayer monovalent (+1) organic spacers in the more popular Ruddlesden-Popper (RP) phases.12 Bulk crystalline powders of (4AMP)(FA)n-1SnnI3n+1 (n=1 to 4) perovskites were prepared by the simple solution-casting method, using experimental procedure described in the Supporting Information (SI). Rietveld refinement of the XRD pattern of the most representative (4AMP)(FA)3Sn4I13 (n=4) sample is presented in Figure 1b, confirming the expected DJ perovskite crystal structure. The direct comparison between the experimental and simulated XRD patterns is shown in Figure S1, where there is good match of the Bragg positions. The observed background in the experimental XRD pattern can be attributed to the presence of some amorphous material. (More comprehensive analyses of the crystal structures of all other DJ phases will be performed in the future.) The (4AMP)(FA)3Sn4I13 perovskite shows reasonable absorption characteristics, with edge at 860 nm, as shown in Figure 1c. The calculated band structure using density functional theory (DFT) shows a consistent value,(13) and reveals slight indirect character of the bandgap (Figure S2). This material also shows a strong, well-resolved steady-state photoluminescence (PL) peak at 840 nm. Surprisingly, the PL lifetime is as long as 18.56 ns, which is significantly longer than that observed in other Sn(II)-based perovskite materials (hundreds of ps to a couple of ns).(5) The PL peak (Figure 1c) suggests an optical bandgap of 1.47 eV. We have further investigated the
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ACS Energy Letters
effect of n on the optical absorption of these DJ perovskites, results from which are shown in Figure S3 and Figure 1c. An increase of n, from 1 to 4, results in a systematic red-shift of the absorption edge and the PL peak. This is because of the change of the dimensionality of the perovskite crystal structure from 2D to ‘quasi-2D,’ similar to the case of RP phases in the (PEA)2(FA)n-1SnnI3n+1 system.(5)
Figure 2. (a) Energy-levels diagram for DJ Sn(II)-based HTL-free PSCs. (b) Typical J-V curves for (4AMP)(FA)3Sn4I13 (n=4) HTL-free PSCs. (c) PCE stability of (4AMP)(FA)3Sn4I13-based HTL-free PSC as a function of storage duration (in N2 atmosphere, at 45 ˚C, under 1-sun illumination).
PSCs based on (4AMP)(FA)3Sn4I13 were then fabricated to evaluate their potential in PV applications. The printable hole-transporting layer (HTL)-free triple-mesoscopic PSC architecture is adopted.(14) The corresponding energy-levels diagram is schematically shown in Figure 2a. Figure 2b presents the current density (J) – voltage (V) curves of a PSC. A promising PCE of 4.22% is obtained, with JSC of 14.90 mA.cm-2, VOC of 0.64 V, and FF of 0.443. The VOC can be improved by tailoring the n value. For example, Figure S4 shows that VOC is increased to 0.80 V when n=1. Therefore, there is room for further improvement in the PCE of these PSCs based on DJ Sn(II)-based perovskites. The PCE of the unencapsulated (4AMP)(FA)3Sn4I13 PSC was also tracked periodically, with the device exposed to 1-sun illumination in N2 atmosphere at ~45 ˚C for 100 hours. Only 9% decay of the initial PCE is observed, demonstrating promising stability of these PSCs. In closing, the synthesis and use of DJ Sn(II)-based halide perovskites for stable, lead-free PVs have been demonstrated here for the first time. We envision ‘quasi-2-D’ DJ Sn(II)-based perovskites having the following potential advantages: (i) reduced propensity for the formation of Sn-vacancies due to the weaker coupling between Sn and I; (ii) enhanced stability due to the stronger inter-layer bonding by divalent organic spacers, compared to the relatively weaker van
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der Waals bonding in the case of monovalent organic spacers in RP phases; and (iii) improvement of electrons/holes diffusion lengths due to the ionic bonding of the divalent organic spacers and the reduced overall organic content.(15) Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: xxxxx. Experimental procedure and additional results are included in the SI. Author Information Corresponding Authors *Email:
[email protected];
[email protected];
[email protected] ORCID Min Chen: 0000-0002-8655-5642 Yue Hu: 0000-0003-0163-4702 Nitin P. Padture: 0000-0001-6622-8559 Notes The authors declare no competing interests. Acknowledgments The funding for this research from the US National Science Foundation (Grant no. OIA-1538893) is gratefully acknowledged. M.G-J. and X.C.Z. acknowledge additional support from the University of Nebraska Holland Computing Center. Y.H., Y.R. and H.H. acknowledge financial support from the National Natural Science Foundation of China (Grant Nos. 21702069, 91733301, 91433203, and 61474049). References 1. 2. 3. 4. 5. 6. 7.
Rong, Y.; Hu, Y.; Mei, A.; Tan, H.; Saidaminov, M. I.; Seok, S.; McGehee, M. D.; Sargent, E. H.; Han, H. Challenges for Commercializing Perovskite Solar Cells. Science. 2018, 361, eaat8235. Zhou Y.; Zhou, Z.; Chen. M.; Zong, Y.; Huang, J.; Pang, J.; Padture, N. P. Doping and Alloying for Improved Perovskite Solar Cells. J. Mater. Chem. A 2016, 4, 17623-17635. Ju M.-G.; Chen, M.; Zhou, Y.; Dai, J.; Ma, L.; Padture, N. P.; Zeng, X. C. Toward EcoFriendly and Stable Perovskite Materials for Photovoltaics. Joule 2018, 2, 1231-1241. Hao F.; Stoumpos C. C.; Cao D. H.; Chang P. H.; Kanatzidis M. G. Lead-Free Solid-State Organic-Inorganic Halide Perovskite Solar Cells. Nature Photon. 2014, 8, 489-494. Wang F.; Jiang, X.; Chen, H; Shang, Y.; Liu, H.; Wei, J.; Zhou, W.; He, H.; Liu, W.; Ning, Z. 2D-Quasi-2D-3D Hierarchy Structure for Tin Perovskite Solar Cells with Efficiency and Stability. Joule 2018, in press. DOI: 10.1016/j.joule.2018.09.012 Xiao Z., Meng W., Wang J., Yan Y. Thermodynamic Stability and Defect Chemistry of Bismuth-Based Lead-Free Double Perovskites. ChemSusChem 2016, 9, 2628-2633. Saparov B.; Hong, F.; Sun, J.; Duan, H,; Meng, W.; Cameron, S.; Hill, I. G.; Yan, Y.; Mitzi, D. B.; Thin-Film Preparation and Characterization of Cs3Sb2I9: A Lead-Free Layered Perovskite Semiconductor. Chem. Mater. 2015, 27, 5622-5632.
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8. 9. 10.
11. 12. 13. 14. 15.
Chen M.; Ju, M.-G.; Carl, A. D.; Zong, Y.; Grimm, R. L.; Gu, J.; Zeng, X. C.; Zhou, Y.; Padture, N. P. Cesium Titanium(IV) Bromide Thin Films Based Stable Lead-Free Perovskite Solar Cells. Joule 2018, 2, 558-570. Ju M.-G.; Chen, M.; Zhou, Y.; Garces, H. F.; Dai, J.; Ma, L.; Padture, N. P. Earth-Abundant Nontoxic Titanium(IV)-Based Vacancy-Ordered Double Perovskite Halides with Tunable 1.0 to 1.8 eV Bandgaps for Photovoltaic Applications. ACS Energy Lett. 2018, 3, 297-304. Chung I.; Song, J.; Im, J.; Androulakis, J.; Malliakas, C. D.; Li, H.; Freeman, A. J.; Kenney, J. T.; Kanatzidis, M. G. CsSnI3: Semiconductor or Metal? High Electrical Conductivity and Strong Near-Infrared Photoluminescence from a Single Material. High Hole Mobility and Phase-Transitions. J. Am. Chem. Soc. 2012, 134, 8579-8587. Wang N.; Zhou, Y.; Ju, M.-G.; Garces, H. F.; Ding, T.; Pang, S.; Zeng, X. C.; Padture, N. P.; Sun, X. W. et al. Heterojunction-Depleted Lead-Free Perovskite Solar Cells with Coarse-Grained B-γ-CsSnI3 Thin Films. Adv. Energy Mater. 2016, 6, 1601130. Mao L.; Ke, W.; Pedesseau, L.; Wu, Y.; Katan, C.; Even, J.; Wasielewski, M. R.; Stoumpos, C. C.; Kanatzidis, M. G. Hybrid Dion-Jacobson 2D Lead Iodide Perovskites. J. Am. Chem. Soc. 2018, 140, 3775-3783. Ma, L.; Ju, M.-G.; Dai, J.; Zeng, X. C. Tin and Germanium Based Two-Dimensional Ruddlesden–Popper Hybrid Perovskites for Potential Lead-Free Photovoltaic and Photoelectronic Applications. Nanoscale 2018, 10, 11314-11319. Mei A.; Li, X.; Liu, L.; Ku, Z.; Liu, T.; Rong, Y.; Xu, M.; Hu, M.; Chen, J.; Yang, Y.; Grätzel, M.; Han, H. A Hole-Conductor-Free, Fully Printable Mesoscopic Perovskite Solar Cell with High Stability. Science 2014, 345, 295-298. Mao L.; Stoumpos, C. C.; Kanatzidis, M. G. Two-Dimennsional Hybrid Halide Perovskites: Princples and Promises. J. Am. Chem. Soc. 2018, in press, DOI: 10.1021/jacs.8b10851
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