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Solution-Processed "Silver-Bismuth-Iodine" Ternary Thin Films for Lead-Free Photovoltaic Absorbers

Published: September 27th, 2018



1Convergence Research Center for Solar Energy, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 2Department of Chemistry and Research Institute for Convergence of Basic Sciences, Hanyang University

Herein, we present detailed protocols for solution-processed silver-bismuth-iodine (Ag-Bi-I) ternary semiconductor thin films fabricated on TiO2-coated transparent electrodes and their potential application as air-stable and lead-free optoelectronic devices.

Bismuth-based hybrid perovskites are regarded as promising photo-active semiconductors for environment-friendly and air-stable solar cell applications. However, poor surface morphologies and relatively high bandgap energies have limited their potential. Silver-bismuth-iodine (Ag-Bi-I) is a promising semiconductor for optoelectronic devices. Therefore, we demonstrate the fabrication of Ag-Bi-I ternary thin films using material solution processing. The resulting thin films exhibit controlled surface morphologies and optical bandgaps according to their thermal annealing temperatures. In addition, it has been reported that Ag-Bi-I ternary systems crystallize to AgBi2I7, Ag2BiI5, etc. according to the ratio of the precursor chemicals. The solution-processed AgBi2I7 thin films exhibit a cubic-phase crystal structure, dense, pinhole-free surface morphologies with grains ranging in size from 200 to 800 nm, and an indirect bandgap of 1.87 eV. The resultant AgBi2I7 thin films show good air stability and energy band diagrams, as well as surface morphologies and optical bandgaps suitable for lead-free and air-stable single-junction solar cells. Very recently, a solar cell with 4.3% power conversion efficiency was obtained by optimizing the Ag-Bi-I crystal compositions and solar cell device architectures.

Solution-processed inorganic thin-film solar cells have been widely studied by many researchers seeking to convert sunlight directly into electricity1,2,3,4,5. With the development of material synthesis and device architecture, lead halide-based perovskites have been reported to be the best solar cell absorbers with a power conversion efficiency (PCE) greater than 22%5. However, there are growing concerns about the use of toxic lead, as well as stability issues of lead-halide perovsk....

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1. Preparation of Bare-glass, Fluorine-doped Tin Oxide (SnO2:F) Substrates

  1. To clean the bare-glass, fluorine-doped tin oxide (FTO) substrates, sonicate them sequentially in an aqueous solution containing 2% Triton, deionized (DI) water, acetone, and isopropyl alcohol (IPA), each for 15 min.
  2. Put the cleaned substrates in the heating oven at 70 °C for 1 h to remove the residual IPA.

2. Preparation of Compact TiO2 Layers (c-TiO2) to.......

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It has been reported that the Ag-Bi-I ternary systems, which are regarded as promising semiconductors, are crystallized in various compositions, such as AgBi2I7, AgBiI4, and Ag2BiI510, according to the molar ratio of AgI to BiI3. Earlier studies have shown that bulk crystal forms with various compositions of Ag-Bi-I ternary systems can be experimentally synthesized by changing the molar ratio of AgI .......

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We have provided a detailed protocol for the solution fabrication of Ag-Bi-I ternary semiconductors, which are to be exploited as lead-free photovoltaic absorbers in thin-film solar cells with mesoscopic device architectures. c-TiO2 layers were formed on FTO substrates to avoid electron leakage flowing into the FTO electrodes. m-TiO2 layers were sequentially formed on c-TiO2-coated FTO substrates to improve the electron extractions generated from the photovoltaic absorbers (i.e.,.......

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This work was supported by the Daegu Gyeongbuk Institute of Science and Technology (DGIST) Research and Development (R&D) Programs of the Ministry of Science, ICT and Future Planning of Korea (18-ET-01). This work was also supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP) and the Ministry of Trade, Industry & Energy(MOTIE) of the Republic of Korea (No. 20173010013200).


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Name Company Catalog Number Comments
Bismuth(III) iodide, Puratronic, 99.999% (metals basis) Afa Aesar 7787-64-6 stored in N2-filled condition
Silver iodide, Premion, 99.999% (metals basis) Afa Aesar 7783-96-2 stored in N2-filled condition
Butylamine 99.5% Sigma-Aldrich 109-73-9
Triton X-100 Sigma-Aldrich 9002-93-1
Isopropyl alcohol (IPA) Duksan 67-63-0 Electric High Purity GRADE
Titanium(IV) isopropoxide Sigma-Aldrich 546-68-9 ≥97.0%
Ethyl alcohol Sigma-Aldrich 64-17-5 200 proof, ACS reagent, ≥99.5%
Hydrochloric acid SAMCHUN 7647-01-0 Extra pure
Titanium tetrachloride (TiCl4) sharechem
50nm-sized TiO2 nanoparticle paste sharechem
2-propanol Sigma-Aldrich 67-63-0 anhydrous, 99.5%
Terpineol Merck 8000-41-7
Heating oven WiseTherm
Oxygen (O2) plasma AHTECH
X-ray diffraction (XRD) Rigaku Rigaku Miniflex 600 diffractometer with a NaI scintillation counter and using monochromatized Cu-Kα radiation
(1.5406 Å wavelength).
Fourier transform infrared (FTIR) Bruker Bruker Tensor 27
field-emission scanning electron microscope (FE-SEM) Hitachi Hitachi SU8230
UV-Vis spectra PerkinElmer PerkinElmer LAMBDA 950
Ultraviolet photoelectron spectroscopy (UPS) RBD Instruments PHI5500 Multi-Technique system

  1. Grätzel, M. The Light and Shade of Perovskite Solar Cells. Nature Materials. 13, 838-842 (2014).
  2. Green, M. A., Ho-Baillie, A., Snaith, H. J. The emergence of perovskite solar cells. Nature Photonics. 8, 506-514 (2014).
  3. Kojima, A., Teshima, K., Shirai, Y., Miyasaka, T. Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells. Journal of American Chemical Society. 131 (17), 6050-6051 (2009).
  4. Burschka, J., et al. Sequential Deposition as a Route to High-Performance Perovskite-Sensitized Solar Cells. Nature. 499, 316-319 (2013).
  5. Yang, W. S., et al. Iodide Management in Formamidinium-Lead-Halide-Based Perovskite Layers for Efficient Solar Cells. Science. 356 (6345), 1376-1379 (2017).
  6. Park, B. -. W., et al. Bismuth Based Hybrid Perovskites A3Bi2I9 (A: Methylammonium or Cesium) for Solar Cell Application. Advanced Materials. 27 (43), 6806 (2015).
  7. Hoye, R. L. Z., et al. Methylammonium Bismuth Iodide as a Lead-Free, Stable Hybrid Organic-Inorganic Solar Absorber. Chemistry−European Journal. 22 (8), 2605-2610 (2016).
  8. Lyu, M., et al. Organic-Inorganic Bismuth (III)-Based Material: A Lead-Free, Air-Stable and Solution-Processable Light-Absorber beyond Organolead Perovskites. Nano Research. 9 (3), 692-702 (2016).
  9. Mitzi, D. B. Organic-Inorganic Perovskites Containing Trivalent Metal Halide Layers: The Templating Influence of the Organic Cation Layer. Inorganic Chemistry. 39 (26), 6107-6113 (2000).
  10. Mashadieva, L. F., Aliev, Z. S., Shevelkov, A. V., Babanly, M. B. Experimental Investigation of the Ag-Bi-I Ternary System and Thermodynamic Properties of the Ternary Phases. Journal of Alloys and Compounds. 551, 512-520 (2013).
  11. Kim, Y., et al. Pure Cubic-Phase Hybrid Iodobismuthates AgBi2I7 for Thin-Film Photovoltaics. Angewandte Chemie International Edition. 55 (33), 9586-9590 (2016).
  12. Fourcroy, P. H., Palazzi, M., Rivet, J., Flahaut, J., Céolin, R. Etude du Systeme AgIBiI3. Materials Research Bulletin. 14 (3), 325-328 (1979).
  13. Kondo, S., Itoh, T., Saito, T. Strongly Enhanced Optical Absorption in Quench-Deposited Amorphous AgI Films. Physical Review B. 57 (20), 13235-13240 (1998).
  14. Kumar, P. S., Dayal, P. B., Sunandana, C. S. On the Formation Mechanism of γ-AgI Thin Films. Thin Solid Films. 357 (2), 111-118 (1999).
  15. Validźić, I. L., Jokanpvić, V., Uskoković, D. P., Nedeljković, J. M. Influence of Solvent on the Structural and Morphological Properties of AgI Particles Prepared Using Ultrasonic Spray Pyrolysis. Materials Chemistry and Physics. 107 (1), 28-32 (2008).
  16. Tezel, F. M., Kariper, &. #. 3. 0. 4. ;. A. Effect of pH on Optic and Structural Characterization of Chemical Deposited AgI Thin Films. Materials Research Ibero-American Journal of Materials. 20 (6), 1563-1570 (2017).
  17. Chai, W. -. X., Wu, L. -. M., Li, J. -. Q., Chen, L. A Series of New Copper Iodobismuthates: Structural Relationships, Optical Band Gaps Affected by Dimensionality, and Distinct Thermal Stabilities. Inorganic Chemistry. 46 (21), 8698-8704 (2007).
  18. Konstantatos, G., et al. Ultrasensitive Solution-Cast Quantum Dot Photodetectors. Nature. 442, 180-183 (2006).
  19. Mercier, N., Louvaina, N., Bi, W. Structural Diversity and Retro-Crystal Engineering Analysis of Iodometalate Hybrids. CrystEngComm. 11 (5), 720-734 (2009).
  20. Zhu, X. H., et al. Effect of Mono- versus Di-ammonium Cation of 2,2'-Bithiophene Derivatives on the Structure of Organic-Inorganic Hybrid Materials Based on Iodo Metallates. Inorganic Chemistry. 42 (17), 5330-5339 (2003).
  21. Zhu, H., Pan, M., Johansson, M. B., Johansson, E. M. J. High Photon-to-Current Conversion in Solar Cells Based on Light-Absorbing Silver Bismuth Iodide. ChemSusChem. 10 (12), 2592-2596 (2017).
  22. Turkevych, I., et al. Photovoltaic Rudorffites: Lead-Free Silver Bismuth Halides Alternative to Hybrid Lead Halide Perovskites. ChemSusChem. 10 (19), 3754-3759 (2017).

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