Next Article in Journal
Fabrication and Characterization of Aluminum Nitride Nanoparticles by RF Magnetron Sputtering and Inert Gas Condensation Technique
Next Article in Special Issue
Special Issue: “Advanced Thin Film Materials for Photovoltaic Applications”
Previous Article in Journal
Construction of Rutile-TiO2 Nanoarray Homojuction for Non-Contact Sensing of TATP under Natural Light
Previous Article in Special Issue
Effect of Thioacetamide Concentration on the Preparation of Single-Phase SnS and SnS2 Thin Films for Optoelectronic Applications
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Coatings
Volume 10
Issue 4
10.3390/coatings10040410
coatings-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Photovoltaic Characteristics of CH3NH3PbI3 Perovskite Solar Cells Added with Ethylammonium Bromide and Formamidinium Iodide

by
Kousuke Nishi
,
Takeo Oku
*,
Taku Kishimoto
,
Naoki Ueoka
and
Atsushi Suzuki
Department of Materials Science, The University of Shiga Prefecture, 2500 Hassaka, Hikone, Shiga 522-8533, Japan
*
Author to whom correspondence should be addressed.
Coatings 2020, 10(4), 410; https://doi.org/10.3390/coatings10040410
Submission received: 1 April 2020 / Revised: 15 April 2020 / Accepted: 16 April 2020 / Published: 20 April 2020
(This article belongs to the Special Issue Advanced Thin Film Materials for Photovoltaic Applications)
Browse Figures
Versions Notes

Abstract

:
Photovoltaic characteristics of solar cell devices in which ethylammonium (EA) and formamidinium (FA) were added to CH3NH3PbI3 perovskite photoactive layers were investigated. The thin films for the devices were deposited by an ordinary spin-coating technique in ambient air, and the X-ray diffraction analysis revealed changes of the lattice constants, crystallite sizes and crystal orientations. By adding FA and EA, surface defects of the perovskite layer decreased, and the photoelectric parameters were improved. In addition, the highly (100) crystal orientations and device stabilities were improved by the EA and FA addition.

1. Introduction

Organic-inorganic perovskite solar cells provide photoelectric conversion in wide wavelength ranges and exhibit excellent photovoltaic properties [1,2,3,4,5,6]. Since the film of CH3NH3PbI3 (MAPbI3) can be formed by a spin-coating method, there is an advantage that the production process is easy and low cost. In spite of these merits, there is a serious problem that the stability is extremely low. In order to solve this problem, research and development of devices with higher power conversion efficiency and stability using formamidinium (FA) [7,8,9,10,11,12,13], guanidinium [14,15] or alkali metal [16,17,18,19,20,21] doped perovskites for the methylammonium (MA) site have been conducted.
There also exists research and development of devices with ethylammonium (EA) added to perovskites [22,23,24,25,26]. EA has a larger ionic radius (2.74 Å) than that of MA (2.17 Å), and the addition of EA can be expected to improve stability from the viewpoint of calculations [25,27] and tolerance factor [1]. In addition, there is a report that the thermal stability and crystallinity are higher than those of MA, and the addition of EA to the perovskites showed a surface coating with fewer defects and improves the stability of the device [23,28]. However, it should be noted that excessive addition of EA leads to phase separation, a decrease in crystallinity, and precipitation of PbI2 as an impurity [29,30].
The purpose of this study is to examine the microstructures and photovoltaic characteristics of FA and EA co-added CH3NH3PbI3 perovskite solar cells. The stability of a MAPbI3 perovskite structure might be predicted by calculating the tolerance factor (t-factor) [31,32,33,34,35], which is given by t = r MA + r I 2 ( r Pb + r I ) , where r is an ionic radius [36]. When the t-factor is in the range of 0.81–1.1, perovskite structures could be formed [35]. If the t-factor is adjusted to 1.0, perovskite structures with cubic symmetry could be realized. The ionic radii of MA+, FA+, EA+, Pb2+, I−, Br−, and Cl− are 2.17, 2.53, 2.74, 1.19, 2.20, 1.96, and 1.81 Å, respectively [35,36]. By adding FA+ and EA+ with larger ionic radii than MA+, t-factor gets closer to 1, and the stability is expected to be improved. In addition, EA addition is expected to promote the crystal growth and improve the stability of the device [23,28], and there are few reports on simultaneous addition of FA and EA to the perovskite layer. The effects of the simultaneous addition to the perovskite compounds were analyzed by microstructural and photovoltaic characterization.

2. Materials and Methods

A cross-section and deposition process of the present perovskite solar cells is summarized and shown in Figure 1. A fluorine-doped tin oxide (FTO, Nippon Sheet Glass Company, Ltd., Tokyo, Japan) substrate was dipped and washed in an ultrasonic washing machine using acetone twice and methanol once, and cleaned with flowing N2. The 0.15 and 0.30 M precursor solutions of TiO2 were prepared from 0.055 and 0.11 mL titanium disopropoxide bis (acetyl acetonate) (Sigma Aldrich, Tokyo, Japan) and 1-btanol (1.0 mL, Nacalai Tesque, Kyoto, Japan). The solutions were cast on the transparent FTO, and spin-coated at 3000 rpm for 30 s and heat-treated at 125 °C for 5 min [37,38,39]. The processes with 0.30 M precursor solutions were repeated twice. In order to form a dense electron transport TiO2, the deposited samples were annealed at 550 °C for 30 min. The mesoporous TiO2 layer was deposited with TiO2 nanoparticles (P-25, Aerosil, Tokyo, Japan) and polyethylene glycol (Nacalai Tesque, Kyoto, Japan) in ultrapure water. The solution was blended with acethylacetone (20 μL, Fujifilm Wako Pure Chemical Corporation, Osaka, Japan) and triton-X-1001 (10 μL, Sigma Aldrich, Tokyo, Japan) for 30 min, and allowed to stand for 24 h to remove bubbles from the mixed solution. The prepared TiO2 mixed solution was spin-coated at 5000 rpm for 30 s and annealed at 550 °C for 30 min, and a mesoporous TiO2 layer was formed.
The perovskite precursor solutions were prepared as mixed solutions of methylamine hydroiodide CH3NH3I (MAI, 2.4 M, Tokyo Chemical Industry, Tokyo, Japan) and PbCl2 (0.8 M, Sigma Aldrich, Tokyo, Japan) in N,N-dimethylformamide (DMF) (0.5 mL, Sigma Aldrich, Tokyo, Japan) at 60 °C for 24 h. This is used as a standard cell, and the amount of MAI was reduced by adding formamidine hydroiodide CH(NH2)2I (FAI, Tokyo Chemical Industry, Tokyo, Japan), ethylamine hydrobromide CH3CH2NH3Br (EABr, Tokyo Chemical Industry, Tokyo, Japan), and ethylamine hydrochloride CH3CH2NH3Cl (EACl, Tokyo Chemical Industry, Tokyo, Japan). Detailed compositions of the perovskite compounds are listed in Table 1, together with the t-factors. The perovskite precursor solutions were spin-coated at 2000 rpm for 60 s and applied an air-blowing method during spin-coating [40,41]. The device was annealed at 150 °C for 20 min in the ambient air.
The hole-transport layer was deposited by spin-coating. A chlorobenzene solution (0.5 mL) of 2,2’,7,7’-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9’-spirobifluorene (spiro-OMeTAD, Fujifilm Wako Pure Chemical, Corporation, Osaka, Japan, 36.1 mg) was prepared by mixing it for 12 h. An acetonitrile solution (0.5 mL) of lithium bis (trifluoromethylsulfonyl) imide (Li-TFSI, Tokyo Chemical Industry, Tokyo, Japan) was also prepared by mixing it for 12 h. A mixture solution of the spiro-OMeTAD solution with 4-tertbutylpridine (14.4 μL, Sigma Aldrich, Tokyo, Japan) and Li-TFSI solution (8.8 μL) was prepared by mixing it at 70 °C for 30 min. The spiro-OMeTAD layer was deposited by spin-coating at 4000 rpm for 30 s. After that, gold (Au) thin film electrodes were deposited as electrodes by vacuum evaporation. As investigated in the previous works [42,43,44], layer thicknesses of the compact TiO2, mesoporous TiO2 + perovskite, spiro-OMeTAD, and Au layers were roughly estimated to be 40, 600, 50, and 200 nm, respectively.
The light-induced current density voltage (J–V) curves of the fabricated devices were obtained by using air mass 1.5 illuminator (San-ei Electric XES-301S, 100 mW·cm−2) and a current-voltage apparatus (B2901A, Keysight, Santa Rosa, CA, USA). In addition, the external quantum efficiencies of the devices were obtained (QE-R, Enli Technology, Kaohsiung, Taiwan). Optical microscopy (Eclipse E600, Nikon, Tokyo, Japan) and X-ray diffraction (D2 PHASER, Bruker, Billerica, MA, USA) measurements were performed to analyze the surface morphologies and nanoscopic structures.

3. Results and Discussion

J–V curves collected in the light condition for the fabricated perovskite solar cells are displayed in Figure 2. Table 2 shows summarized parameters of the fabricated solar cells. A conversion efficiency (η) of the standard cell is 6.72%. The JSC, VOC and η were improved from 19.2 mA·cm−2, 0.687 V and 6.72% to 21.5 mA·cm−2, 0.922 V and 14.25% by addition of FA 20% at the MA site. When EA 10% and FA 10% were added simultaneously, the JSC, VOC and η increased 19.9 mA cm−2, 0.946 V and 12.43%. Addition of EACl was also effective for the improvement of the device properties. Further addition of EA and FA would decrease the device performance.
Figure 3 is the J–V curves of the fabricated photovoltaic cells after 4 weeks in ambient air, and the estimated parameters are shown in Table 3. The conversion efficiency of the standard cell was lowered to 5.69%. Co-addition of small amount of EA and FA to MAPbI3 provided higher stability compared with the standard cells, as shown in Figure 4.
Optical microscopy images of the perovskites through spiro-OMeTAD are shown Figure 5. By adding EA and FA, surface defects of the perovskite layer decreased. Obtaining a perovskite layer with few defects enables efficient charge separation and charge extraction, which is thought to have led to improved device performance. In addition, defects in the perovskite layer are a cause of charge recombination, and it is considered that suppression of the defect has led to improvement in stability.
External quantum efficiency (EQE) spectra of the fabricated photovoltaic cells are shown in Figure 6. The band gap energies (Eg) were estimated from EQE spectra around 800 nm by linear fitting using band gap calculator software (Enli Technology, QE-R), and the measured band gap energies of the perovskite compounds increased from 1.54 to 1.57 eV by adding EA. The Eg value of the 20% EABr-added perovskite crystals was wider than that of the 20%FAI-added perovskite. The EQE values of the EABr-added device was lower between 350 and 750 nm than that of the FAI-added device, which led to a decrease of the JSC values.
X-ray diffraction (XRD) patterns of the fabricated cells added with EABr and FAI are shown in Figure 7a. Increases of (100) and (200) diffraction reflections are observed by adding FAI or EABr. In addition, only (100) and (200) peaks are observed, which indicates that the cells exhibited highly oriented (100) perovskite crystals by the air-blowing method [40].
Microstructural parameters of the present perovskite compounds are listed in Table 4. The lattice constants of the FAI-added perovskites were higher compared with the standard MAPbI3 material, whereas those of the EABr and FAI co-added perovskite decreased. Crystallite sizes were estimated from the (200) reflections, and they increased by the addition of FAI and EABr. The I100/I210 intensity ratios of (100) reflections (I100) to (210) reflections (I210) were measured from the XRD data in Figure 7a,b, and the results are shown in Table 4. If the CH3NH3PbI3 cubic perovskite particles are randomly oriented, then the I100/I210 value should be 2.08 [35]. For the standard cell prepared in the present study, the I100/I210 is 48, which means the (100) crystal surfaces of the cubic structures are strongly aligned in the solar cell. By the addition of FAI to the perovskite compounds, I100/I210 was increased to 1694, and the I100/I210 increased further to 1939 by adding EABr. This is 40 times higher than the I100/I210 of the standard perovskite device.
A schematic model showing molecular structures (MA, FA, and EA) and the lattice structure of the FAI and EABr added perovskites is shown in Figure 8a,b, respectively. The lattice constant a of 6.315 Å for a perovskite single crystal [35,45] is greater compared with the a of the perovskite compound in a cell configuration [46,47]. If the perovskite particles were synthesized and deposited on the mesoporous TiO2 layer, some of the CH3NH2 molecules might be desorbed. Then, MA vacancies could be formed, and the lattice constant (6.274 Å) of MAPbI3 is smaller than that of single crystal, as listed in Table 4. When FAI was added to the standard MAPbI3, the FA would occupy the defects and MA sites, and the lattice constant increased to 6.286 Å, as shown in Figure 8b and Table 4. As the size of Br− is fairly small compare with that of I−, a values of the EABr-added crystals decreased to 6.280 Å compared with FAI-added perovskite crystals, as indicated by arrows in Figure 8b. Combination of the present EA/FA with other molecules [15,48] and alkali metals [21,49] might also be effective for the stabilization of the perovskite compounds.

4. Conclusions

Solar cells using perovskite in the photoactive layer were produced by using spin-coating technique in ordinary air, and the influence on photovoltaic characteristics by adding EA and FA to the perovskite phase was investigated. From the results of J–V characteristics, the addition of EA and FA improved VOC and FF, leading to an improvement in photoelectric conversion efficiency. Devices with EA and FA added maintained photoelectric conversion efficiencies even after 4 weeks compared to that of the standard device. Optical microscope results showed surface improvement, and X-ray diffraction results showed FA and EA substitution at MA position of the perovskite. By substituting FA and EA, which have larger ionic radii than MA, the perovskite structures would have more stable cubic structures with higher stability.

Author Contributions

Conceptualization, K.N. and T.O.; Methodology, K.N., T.K., N.U., and A.S.; Formal Analysis, K.N. and T.O.; Investigation, K.N.; Data Curation, K.N. and T.O.; Writing-Original Draft Preparation, K.N. and T.O.; Writing-Review & Editing, T.O.; Visualization, K.N. and T.O.; Supervision, T.O.; Project Administration, T.O.; Funding Acquisition, T.O. All authors have read and agreed to the published version of the manuscript.

Funding

This research was partly funded by the Super Cluster Program of the Japan Science and Technology Agency (JST).

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Green, M.A.; Ho-Baillie, A.; Snaith, H.J. The emergence of perovskite solar cells. Nat. Photon 2014, 8, 506–514. [Google Scholar] [CrossRef]
  2. Chen, Q.; Marco, N.D.; Yang, Y.M.; Song, T.B.; Chen, C.C.; Zhao, H.; Hong, Z.; Zhou, H.; Yang, Y. Under the spotlight: The organic—Inorganic hybrid halide perovskite for optoelectronic applications. Nanotoday 2015, 10, 355–396. [Google Scholar] [CrossRef] [Green Version]
  3. Chen, Y.; He, M.; Peng, J.; Sun, Y.; Liang, Z. Structure and growth control of organic-inorganic halide perovskites for optoelectronics: From polycrystalline films to single crystals. Adv. Sci. 2016, 3, 1500392. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  4. Saliba, M.; Correa-Baena, J.P.; Wolff, C.M.; Stolterfoht, M.; Phung, N.; Albrecht, S.; Neher, D.; Ababe, A. How to make over 20% efficient perovskite solar cells in regular (n–i–p) and inverted (p–i–n) architectures. Chem. Mater. 2018, 30, 4193–4201. [Google Scholar] [CrossRef]
  5. Wu, C.; Chen, K.; Guo, D.Y.; Wang, S.L.; Li, P.G. Cations substitution tuning phase stability in hybrid perovskite single crystals by strain relaxation. RSC Adv. 2018, 8, 2900–2905. [Google Scholar] [CrossRef] [Green Version]
  6. Zhao, Y.; Ye, Q.; Chu, Z.; Gao, F.; Zhang, X.; You, J. Recent progress in high-efficiency planar-structure perovskite solar cells. Energy Environ. Mater. 2019, 2, 93–106. [Google Scholar] [CrossRef] [Green Version]
  7. Weller, M.T.; Weber, O.J.; Frost, J.M.; Walsh, A. Cubic perovskite structure of black Formamidinium Lead Iodide, α-[HC(NH2)2]PbI3, at 298 K. J. Phys. Chem. Lett. 2015, 6, 3209–3212. [Google Scholar] [CrossRef]
  8. Zhao, Y.; Tan, H.; Yuan, H.; Yang, Z.; Fan, J.Z.; Kim, J.; Voznyy, O.; Gong, X.; Quan, L.N.; Tan, C.S.; et al. Perovskite seeding growth of formamidinium-lead-iodide-based perovskites for efficient and stable solar cells. Nature 2018, 9, 1607. [Google Scholar] [CrossRef]
  9. Yang, W.S.; Park, B.W.; Jung, E.H.; Jeon, N.J.; Kim, Y.C.; Lee, D.U.; Shin, S.S.; Seo, J.; Kim, E.K.; Noh, J.H.; et al. Iodide management in formamidinium-lead-halide-based perovskite layers for efficient solar cells. Science 2017, 356, 1376–1379. [Google Scholar] [CrossRef] [Green Version]
  10. Chen, Z.; Zheng, X.; Yao, F.; Ma, J.; Tao, C.; Fang, G. Methylammonium, formamidinium and ethylenediamine mixed triple-cation perovskite solar cells with high efficiency and remarkable stability. J. Mater. Chem. A 2018, 6, 17625–17632. [Google Scholar] [CrossRef]
  11. Shao, S.; Dong, J.; Duim, H.; Brink, G.H.T.; Black, G.R.; Portale, G.; Loi, M.A. Enhancing the crystallinity and perfecting the orientation of formamidinium tin iodide for highly efficient Sn-based perovskite solar cells. Nano Energy 2019, 60, 810–816. [Google Scholar] [CrossRef]
  12. Tavakoli, M.M.; Yadav, P.; Prochowicz, D.; Sponseller, M.; Osherov, A.; Bulovic, V.; Kong, J. Controllable perovskite crystallization via antisolvent technique using chloride additives for highly efficient planar perovskite solar cells. Adv. Energy Mater. 2019, 9, 1803587. [Google Scholar] [CrossRef]
  13. Lu, Y.A.; Chang, T.H.; Wu, S.H.; Liu, C.C.; Lai, K.W.; Chang, Y.C.; Lu, H.C.; Chu, C.W.; Ho, K.C. Coral-like perovskite nanostructures for enhanced light-harvesting and accelerated charge extraction in perovskite solar cells. Nano Energy 2019, 58, 138–146. [Google Scholar] [CrossRef]
  14. Alharbi, E.A.; Alyamani, A.Y.; Kubicki, D.J.; Uhl, A.R.; Walder, B.J.; Alanazi, A.Q.; Luo, J.; Burgos-Caminal, A.; Albadri, A.; Albrithen, H.; et al. Atomic-level passivation mechanism of ammonium salts enabling highly efficient perovskite solar cells. Nat. Commun. 2019, 10, 3008. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  15. Kishimoto, T.; Suzuki, A.; Ueoka, N.; Oku, T. Effects of guanidinium addition to CH3NH3PbI3-xClx perovskite photovoltaic devices. J. Ceram. Soc. Jpn. 2019, 127, 491–497. [Google Scholar] [CrossRef] [Green Version]
  16. Hu, Y.; Ayguler, M.F.; Petrus, M.L.; Bein, T.; Docampo, P. Impact of rubidium and cesium cations on the moisture stability of multiple-cation mixed-halide perovskites. ACS Energy Lett. 2017, 2, 2212–2218. [Google Scholar] [CrossRef] [Green Version]
  17. Hu, Y.; Hutter, E.M.; Rieder, P.; Grill, I.; Hanisch, J.; Ayguler, M.F.; Hufnagel, A.G.; Handloser, M.; Bein, T.; Hartschuh, A.; et al. Understanding the role of cesium and rubidium additives in perovskite solar cells: Trap states, charge transport, and recombination. Adv. Energy Mater. 2018, 8, 1703057. [Google Scholar] [CrossRef]
  18. Zhao, W.; Yao, Z.; Yu, F.; Yang, D.; Liu, S.F. Alkali metal doping for improved CH3NH3PbI3 perovskite solar cells. Adv. Sci. 2018, 5, 1700131. [Google Scholar] [CrossRef] [Green Version]
  19. Ling, T.; Zou, X.; Cheng, J.; Yang, Y.; Ren, H.; Chen, D. Modulating surface morphology related to crystallization speed of perovskite grain and semiconductor properties of optical absorber layer under controlled doping of potassium ions for solar cells. Materials 2018, 11, 1605. [Google Scholar] [CrossRef] [Green Version]
  20. Machiba, H.; Oku, T.; Kishimoto, T.; Ueoka, N.; Suzuki, A. Fabrication and evaluation of K-doped MA0.8FA0.1K0.1PbI3(Cl) perovskite solar cells. Chem. Phys. Lett. 2019, 730, 117–123. [Google Scholar] [CrossRef]
  21. Ueoka, N.; Oku, T.; Suzuki, A. Additive effects of alkali metals on Cu-modified CH3NH3PbI3-δClδ photovoltaic devices. RSC Adv. 2019, 9, 24231–24240. [Google Scholar] [CrossRef] [Green Version]
  22. Hsu, H.L.; Chang, C.C.; Chen, C.P.; Jiang, B.H.; Jeng, R.J.; Cheng, C.H. High-performance and high-durability perovskite photovoltaic devices prepared using ethylammonium iodide as an additive. J. Mater. Chem. A 2015, 3, 9271–9277. [Google Scholar] [CrossRef]
  23. Zheng, H.; Liu, G.; Chen, X.; Zhang, B.; Alsaedi, A.; Hayat, T.; Pan, X.; Dai, S. High-performance mixed-dimensional perovskite solar cells with enhanced stability against humidity, heat and UV light. J. Mater. Chem. A 2018, 6, 20233–20241. [Google Scholar] [CrossRef]
  24. Wang, Y.; Zhang, T.; Li, G.; Xu, F.; Li, Y.; Yang, Y.; Zhao, Y. A mixed-cation lead iodide MA1−xEAxPbI3 absorber for perovskite solar cells. J. Energy Chem. 2018, 27, 215–218. [Google Scholar] [CrossRef] [Green Version]
  25. Liu, D.; Li, Q.; Wu, K. Ethylammonium as an alternative cation for efficient perovskite solar cells from first-principles calculations. RSC Adv. 2019, 9, 7356–7361. [Google Scholar] [CrossRef] [Green Version]
  26. Dhar, A.; Dey, A.; Maiti, P.; Paul, P.K.; Roy, S.; Paul, S.; Vekariya, R.L. Fabrication and characterization of next generation nano-structured organo-lead halide-based perovskite solar cell. Ionics 2018, 24, 1227–1233. [Google Scholar] [CrossRef]
  27. Arkan, F.; Mohammad, I. Computational modeling of the photovoltaic activities in EABX3 (EA = ethylammonium, B = Pb, Sn, Ge, X = Cl, Br, I) perovskite solar cells. Comput. Mater. Sci. 2018, 152, 324–330. [Google Scholar] [CrossRef]
  28. Zhang, F.; Cong, J.; Li, Y.; Bergstrand, J.; Liu, H.; Cai, B.; Hajian, A.; Yao, Z.; Wang, L.; Hao, Y.; et al. A facile route to grain morphology controllable perovskite thin films towards highly efficient perovskite solar cells. Nano Energy 2018, 53, 405–414. [Google Scholar] [CrossRef]
  29. Liu, F.; Dong, Q.; Wong, M.K.; Djiurisic, A.B.; Ng, A.; Ren, Z.; Shen, Q.; Surya, C.; Chan, W.K.; Wang, J.; et al. Perovskite solar cells: Is excess PbI2 beneficial for perovskite solar cell performance? Adv. Energy Mater. 2016, 6, 1502206. [Google Scholar] [CrossRef]
  30. Ueoka, N.; Oku, T. Stability characterization of PbI2-added CH3NH3PbI3−xClx photovoltaic devices. ACS Appl. Mater. Interfaces 2018, 10, 44443–44451. [Google Scholar] [CrossRef]
  31. Hoefler, S.F.; Trimmel, G.; Rath, T. Progress on lead-free metal halide perovskites for photovoltaic applications: A review. Mon. Chem. 2017, 148, 795–826. [Google Scholar] [CrossRef] [Green Version]
  32. Xu, F.; Zhang, T.; Li, G.; Zhao, Y. Mixed cation hybrid lead halide perovskites with enhanced performance and stability. J. Mater. Chem. A 2017, 5, 11450–11461. [Google Scholar] [CrossRef]
  33. Sampson, M.D.; Park, J.S.; Schaller, R.D.; Chan, M.K.Y.; Martinson, A.B.F. Transition metal-substituted lead halide perovskite absorbers. J. Mater. Chem. A 2017, 5, 3578–3588. [Google Scholar] [CrossRef]
  34. Tanaka, H.; Oku, T.; Ueoka, N. Structural stabilities of organic–inorganic perovskite crystals. Jpn. J. Appl. Phys. 2018, 57, 08RE12. [Google Scholar] [CrossRef]
  35. Oku, T. Crystal structures of perovskite halide compounds used for solar cells. Rev. Adv. Mater. Sci. 2020, 59. in press. [Google Scholar] [CrossRef]
  36. Shannon, R.D. Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Cryst. A 1976, 32, 751–767. [Google Scholar] [CrossRef]
  37. Taguchi, M.; Suzuki, A.; Oku, T.; Fukunishi, S.; Minami, S.; Okita, M. Effects of decaphenylcyclopentasilane addition on photovoltaic properties of perovskite solar cells. Coatings 2018, 8, 461. [Google Scholar] [CrossRef] [Green Version]
  38. Oku, T.; Nomura, J.; Suzuki, A.; Tanaka, H.; Fukunishi, S.; Minami, S.; Tsukada, S. Fabrication and characterization of CH3NH3PbI3 perovskite solar cells added with polysilanes. Int. J. Photoenergy 2018, 1155, 1–7. [Google Scholar] [CrossRef] [Green Version]
  39. Taguchi, M.; Suzuki, A.; Oku, T.; Ueoka, N.; Minami, S.; Okita, M. Effects of annealing temperature on decaphenylcyclopentasilane-inserted CH3NH3PbI3 perovskite solar cells. Chem. Phys. Lett. 2019, 737, 136822. [Google Scholar] [CrossRef]
  40. Oku, T.; Ohishi, Y.; Ueoka, N. Highly (100)-oriented CH3NH3PbI3 (Cl) perovskite solar cells prepared with NH4Cl using an air blow method. RSC Adv. 2018, 8, 10389–10395. [Google Scholar] [CrossRef] [Green Version]
  41. Oku, T.; Ohishi, Y. Effects of annealing on CH3NH3PbI3 (Cl) perovskite photovoltaic devices. J. Ceram. Soc. Jpn. 2018, 126, 56–60. [Google Scholar] [CrossRef] [Green Version]
  42. Oku, T.; Ueoka, N.; Suzuki, K.; Suzuki, A.; Yamada, M.; Sakamoto, H.; Minami, S.; Fukunishi, S.; Kohno, K.; Miyauchi, S. Fabrication and characterization of perovskite photovoltaic devices with TiO2 nanoparticle layers. AIP Conf. Proc. 2017, 1807, 020014-1–020014-7. [Google Scholar]
  43. Ueoka, N.; Oku, T.; Suzuki, A.; Sakamoto, H.; Yamada, M.; Minami, S.; Miyauchi, S. Fabrication and characterization of CH3NH3(Cs)Pb(Sn)I3(Cl) perovskite solar cells with TiO2 nanoparticle layers. Jpn. J. Appl. Phys. 2018, 57, 02CE03-1–02CE03-7. [Google Scholar] [CrossRef]
  44. Ueoka, N.; Oku, T.; Tanaka, H.; Suzuki, A.; Sakamoto, H.; Yamada, M.; Minami, S.; Miyauchi, S.; Tsukada, S. Effects of PbI2 addition and TiO2 electron transport layers for perovskite solar cells. Jpn. J. Appl. Phys. 2018, 57, 08RE05-1–08RE05-7. [Google Scholar] [CrossRef]
  45. Ren, Y.; Oswald, I.W.H.; Wang, X.; McCandless, G.T.; Chan, J.Y. Orientation of organic cations in hybrid inorganic−organic perovskite CH3NH3PbI3 from subatomic resolution single crystal neutron diffraction structural studies. Cryst. Growth Des. 2016, 16, 2945–2951. [Google Scholar] [CrossRef]
  46. Oku, T.; Zushi, M.; Imanishi, Y.; Suzuki, A.; Suzuki, K. Microstructures and photovoltaic properties of perovskite-type CH3NH3PbI3 compounds. Appl. Phys. Express 2014, 7, 121601. [Google Scholar] [CrossRef]
  47. Oku, T.; Ohishi, Y.; Suzuki, A. Effects of antimony addition to perovskite-type CH3NH3PbI3 photovoltaic devices. Chem. Lett. 2016, 45, 134–136. [Google Scholar] [CrossRef] [Green Version]
  48. Jodlowski, A.; Roldán-Carmona, C.; Grancini, G.; Salado, M.; Ralaiarisoa, M.; Ahmad, S.; Koch, N.; Camacho, L.; Miguel, G.; Nazeeruddin, M. Large guanidinium cation mixed with methylammonium in lead iodide perovskites for 19% efficient solar cells. Nat. Energy 2017, 2, 972–979. [Google Scholar] [CrossRef] [Green Version]
  49. Jalebi, M.A.; Garmaroudi, Z.A.; Pearson, A.J.; Divitini, G.; Cacovich, S.; Philippe, B.; Rensmo, H.; Ducati, C.; Friend, R.H.; Stranks, S.D. Potassium- and rubidium-passivated alloyed perovskite films: Optoelectronic properties and moisture stability. ACS Energy Lett. 2018, 3, 2671–2678. [Google Scholar] [CrossRef]
Coatings 10 00410 g001 550
Figure 1. Cross-section of the cell and process conditions.
Figure 1. Cross-section of the cell and process conditions.
Coatings 10 00410 g001
Coatings 10 00410 g002 550
Figure 2. J–V characteristics collected in light condition for the fabricated solar cells.
Figure 2. J–V characteristics collected in light condition for the fabricated solar cells.
Coatings 10 00410 g002
Coatings 10 00410 g003 550
Figure 3. J–V characteristics collected in light condition for the fabricated solar cells after 4 weeks in ambient air without encapsulation.
Figure 3. J–V characteristics collected in light condition for the fabricated solar cells after 4 weeks in ambient air without encapsulation.
Coatings 10 00410 g003
Coatings 10 00410 g004 550
Figure 4. Stability measurements of the fabricated perovskite devices.
Figure 4. Stability measurements of the fabricated perovskite devices.
Coatings 10 00410 g004
Coatings 10 00410 g005 550
Figure 5. Optical microscopy images of cells with the compositions of (a) FAI 20%, (b) EABr 5% + FAI 20%, (c) EABr 10% + FAI 20%, and (d) EABr 20% + FAI 20%.
Figure 5. Optical microscopy images of cells with the compositions of (a) FAI 20%, (b) EABr 5% + FAI 20%, (c) EABr 10% + FAI 20%, and (d) EABr 20% + FAI 20%.
Coatings 10 00410 g005
Coatings 10 00410 g006 550
Figure 6. External quantum efficiency spectra of the fabricated solar cells.
Figure 6. External quantum efficiency spectra of the fabricated solar cells.
Coatings 10 00410 g006
Coatings 10 00410 g007 550
Figure 7. (a) X-ray diffraction (XRD) pattern of the present solar cells and (b) enlarged pattern of (a).
Figure 7. (a) X-ray diffraction (XRD) pattern of the present solar cells and (b) enlarged pattern of (a).
Coatings 10 00410 g007
Coatings 10 00410 g008 550
Figure 8. Structures of (a) methylammonium (MA), formamidinium (FA), ethylammonium (EA) and (b) the present perovskite compounds.
Figure 8. Structures of (a) methylammonium (MA), formamidinium (FA), ethylammonium (EA) and (b) the present perovskite compounds.
Coatings 10 00410 g008
Table
Table 1. Compositions and calculated t-factors of the present perovskite compounds.
Table 1. Compositions and calculated t-factors of the present perovskite compounds.
Composition of PerovskiteEABr (%)FAI (%)t-Factor
MAPbI3000.912
MA0.9FA0.1PbI30100.919
MA0.8FA0.2PbI30200.927
MA0.5FA0.5PbI30500.949
MA0.8FA0.1EA0.1PbI2.7Br0.310100.933
MA0.75FA0.2EA0.05PbI2.85Br0.155200.933
MA0.7FA0.2EA0.1PbI2.7Br0.310200.940
MA0.6FA0.2EA0.2PbI2.4Br0.620200.954
MA0.75FA0.2EA0.05PbI2.85Cl0.155200.934
MA0.7FA0.2EA0.1PbI2.7Cl0.310200.941
Table
Table 2. Measured parameters of the cells fabricated in this study. JSC: short-circuit current density. VOC: open-circuit voltage. FF: fill factor. RS: series resistance. RSh: shunt resistance. η: conversion efficiency. ηave: averaged efficiency of three cells.
Table 2. Measured parameters of the cells fabricated in this study. JSC: short-circuit current density. VOC: open-circuit voltage. FF: fill factor. RS: series resistance. RSh: shunt resistance. η: conversion efficiency. ηave: averaged efficiency of three cells.
DeviceJSC
(mA·cm−2)		VOC
(V)		FFRS
(Ω·cm2)		RSh
(Ω·cm2)		η
(%)		ηave
(%)
Standard19.20.6870.5098.83376.726.35
+FAI 10%21.80.8160.5746.2166310.248.04
+FAI 20%21.50.9220.7193.4483914.2513.66
+FAI 50%15.70.9260.7124.713,54510.3610.31
EABr 10% + FAI 10%19.90.9460.6606.1466712.4312.23
EABr 5% + FAI 20%21.00.8340.6485.6495211.3310.63
EABr 10% + FAI 20%19.30.7890.5725.710158.478.70
EABr 20% + FAI 20%18.10.8510.5624.823408.688.27
EACl 5% + FAI 20%20.40.8790.6186.4187911.0610.63
EACl 10% + FAI 20%20.20.9330.6475.266,63712.2111.64
Table
Table 3. Measured photovoltaic parameters of the fabricated cells after 4 weeks.
Table 3. Measured photovoltaic parameters of the fabricated cells after 4 weeks.
DeviceJSC
(mA·cm−2)		VOC
(V)		FFRS
(Ω·cm2)		RSh
(Ω·cm2)		η
(%)		ηave
(%)
Standard19.00.6330.4748.92125.695.25
+FAI 10%17.30.9250.6158.751239.859.30
+FAI 20%20.70.9610.6754.6245513.4313.30
+FAI 50%14.80.9640.6846.075,9689.748.99
EABr 10% + FAI 10%17.30.9250.6158.751239.859.30
EABr 5% + FAI 20%18.60.9190.6995.219,97111.9311.41
EABr 10% + FAI 20%18.20.8190.5647.611298.396.86
EABr 20% + FAI 20%18.20.8700.5856.69469.268.77
EACl 5% + FAI 20%17.30.9000.6825.1409710.629.98
EACl 10% + FAI 20%17.00.9320.6645.8540710.549.49
Table
Table 4. Microstructural parameters for the perovskite crystals. Preferred crystal orientations were indicated with ratios of 100 diffraction intensities (I100) to 210 diffraction intensities (I210).
Table 4. Microstructural parameters for the perovskite crystals. Preferred crystal orientations were indicated with ratios of 100 diffraction intensities (I100) to 210 diffraction intensities (I210).
PerovskitesLattice Constant
a (Å)		Crystallite Size
D200 (Å)		Orientation
I100/I210
Standard6.274(1)47948
+FAI 20%6.286(1)6471694
EABr 5% + FAI 20%6.281(0)528460
EABr 10% + FAI 20%6.283(1)15061155
EABr 20% + FAI 20%6.280(2)8301939

Share and Cite

MDPI and ACS Style

Nishi, K.; Oku, T.; Kishimoto, T.; Ueoka, N.; Suzuki, A. Photovoltaic Characteristics of CH3NH3PbI3 Perovskite Solar Cells Added with Ethylammonium Bromide and Formamidinium Iodide. Coatings 2020, 10, 410. https://doi.org/10.3390/coatings10040410

AMA Style

Nishi K, Oku T, Kishimoto T, Ueoka N, Suzuki A. Photovoltaic Characteristics of CH3NH3PbI3 Perovskite Solar Cells Added with Ethylammonium Bromide and Formamidinium Iodide. Coatings. 2020; 10(4):410. https://doi.org/10.3390/coatings10040410

Chicago/Turabian Style

Nishi, Kousuke, Takeo Oku, Taku Kishimoto, Naoki Ueoka, and Atsushi Suzuki. 2020. "Photovoltaic Characteristics of CH3NH3PbI3 Perovskite Solar Cells Added with Ethylammonium Bromide and Formamidinium Iodide" Coatings 10, no. 4: 410. https://doi.org/10.3390/coatings10040410

APA Style

Nishi, K., Oku, T., Kishimoto, T., Ueoka, N., & Suzuki, A. (2020). Photovoltaic Characteristics of CH3NH3PbI3 Perovskite Solar Cells Added with Ethylammonium Bromide and Formamidinium Iodide. Coatings, 10(4), 410. https://doi.org/10.3390/coatings10040410

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop