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Article

Effect of Ammonium Halide Additives on the Performance of Methyl Amine Based Perovskite Solar Cells

by
Do Yeon Heo
1,
Zhengtang Luo
2,* and
Soo Young Kim
1,*
1
School of Chemical Engineering and Materials Science, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Korea
2
Department of Chemical and Biomolecular Engineering, the University of Hong Kong Science and Technology, Clear Water Bay, Kowloon, Hong Kong
*
Authors to whom correspondence should be addressed.
Materials 2018, 11(8), 1417; https://doi.org/10.3390/ma11081417
Submission received: 16 July 2018 / Revised: 6 August 2018 / Accepted: 8 August 2018 / Published: 13 August 2018
(This article belongs to the Special Issue Advances in Organic and Perovskite Solar Cells)
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Versions Notes

Abstract

:
CH3NH3PbI3-xClx species were fabricated as light-absorbing layers for perovskite solar cells (PSCs), by employing NH4I, NH4Br, and NH4Cl as additives via annealing at 100 °C for different times. Solutions containing CH3NH3I, PbI2, and PbCl2 (4:1:1 molar ratio) in N,N-dimethylformamide were used to prepare perovskites with NH4I, NH4Br, and NH4Cl as additives, at concentrations of 0.1 M and 0.3 M. The additives helped increase the grain size and reduce pinholes in the perovskite films, as confirmed by field-emission scanning electron microscopy. The X-ray diffraction profiles of CH3NH3PbI3-xClx clearly showed peaks at 14° and 28° for the samples with additives, indicative of crystallinity. The best PSC performance with a power conversion efficiency of 9.13%, was achieved using 0.1 M NH4I by annealing for 5 min, whereas the power conversion efficiency of the perovskite solar cells without additives was 5.40%.

1. Introduction

In 2009, perovskite was first used as a sensitizer for light absorption in dye-sensitized solar cells (DSSCs), which gave a power conversion efficiency (PCE) of 3.8% [1]. Perovskite has an ABX3 structure, where A, B, and X represent an organic cation, metal cation, and halide ion, respectively. Given perovskites have high absorption coefficients in the visible region, perovskite nanocrystals, especially CH3NH3PbX3 (X = Br, I, Cl), are used as light absorbers. Park et al. achieved an improved PCE of 6.54% by using CH3NH3PbI3 in DSSCs, in 2011 [2]. In 2012, CH3NH3PbI3 and CH3NH3PbI2Cl were used as absorbers in solid-state hybrid solar cells to obtain PCEs of 9.7% and 10.9%, respectively [3,4], and research to increase the PCE of perovskite solar cells (PSCs) is ongoing [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27]. In 2017, Seok and coworkers achieved a PCE of PSCs, as high as 22.1% [28].
The quality of the perovskite layer is important for increasing the PCE of PSCs [28,29,30,31,32]. Research to improve the quality of perovskite films by using additives is currently being pursued. For example, the addition of CH3NH3Cl [33], CaCl2 [34], InCl3 [35], NH4Cl [36,37] etc., has been found to improve the morphology of perovskite films, thereby improving the performance of PSCs. PSCs with Cl-containing additives, showed high electrical conductivity and a long carrier diffusion length. Additives including, I− also affect the performance of PSCs. When NaI [38], CuI [38], HI [39], and NH4I [40] were used as additives, the PCEs of the resulting PSCs were 15.14%, 15.25%, 17.60%, and 18.31% respectively, which were higher compared to that of the PSCs without additives. Previous studies have shown that additives improve the morphology of perovskite films and increase the PCE of PSCs.
In this study, NH4I, NH4Br, and NH4Cl were used as additives in the perovskite solution for film formation via spin-coating. The CH3NH3PbI3-xClx perovskite solution for spin-coating was prepared in dimethylformamide (DMF). The concentration of the additives was varied, between 0.1 M and 0.3 M. After spin-coating, the perovskite films were annealed at 100 °C for 1, 5, 10, and 30 min. PSCs with an indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/CH3NH3PbI3-xClx perovskite/[6,6]-phenyl-C60 butyric acid methyl ester (PCBM)/bathocuproine (BCP)/LiF/Al device structure were fabricated. This study mainly shows device optimization through the change of various additives (NH4I, NH4Br, NH4Cl), amounts of additives (0.1 M and 0.3 M), and annealing time (1, 5, 10, and 30 min), respectively. The characteristics of the CH3NH3PbI3-xClx PSCs, were evaluated by controlling the annealing time and the concentration of additives, demonstrating that the PCE of the PSCs was improved by the additives. The details of the characteristics of the PSCs and the effects of the additives are discussed herein.

2. Experimental Details

2.1. Fabrication of CH3NH3PbI3-xClx PSCs

ITO-coated glass (Woo Yang GMS, 15 Ω sq−1) was used as the substrate. The glass was cleaned by successive ultrasonication in acetone, isopropyl alcohol, and deionized water for 15 min each. The substrate was then treated with UV-ozone for 15 min. A hole transport layer of PEDOT:PSS (Clevious) was spin-coated onto the glass substrate at 4000 rpm for 30 s, followed by heating at 150 °C for 15 min in air. The substrates were loaded into a N2-filled glove box. As for synthesis of the CH3NH3PbI3-xClx precursor, CH3NH3I, lead(II) iodide (PbI2), and lead(II) chloride (PbCl2) in a 4:1:1 molar ratio, were dissolved in an anhydrous DMF. Thereafter, 0.1 M or 0.3 M NH4I, NH4Br, and NH4Cl were added to the solution. The precursor solution was then spin-coated onto the PEDOT:PSS layer at 4000 rpm for 30 s. The substrates were subsequently annealed at 100 °C for 1, 5, 10, and 30 min. A PCBM (Nanoholdings) solution (40 mg mL−1) in chlorobenzene was then spin-coated on top of the perovskite film at 750 rpm for 15 s and the substrate was heated at 60 °C for 5 min. Subsequently, films of BCP (3 nm, Taewon Scientific CO, Seoul, Korea), LiF (1 nm, Taewon Scientific CO, Seoul, Korea), and Al (100 nm) were deposited on top of the electron transport layer (PCBM layer) under vacuum (<10−6 Torr) using a thermal evaporator, as shown in Figure 1. BCP and LiF, were used as hole blocking layers and Al was used as an electrode.

2.2. Characterizations

The X-ray diffraction (XRD, D8-Advance/Bruker-AXS (Billerica, MA, USA)) patterns were measured in an angle range of 2θ = 10° to 50°. The morphology of the films was shown through field emission scanning electron microscope (FE-SEM, Carl Zeiss, SIGMA (Kawasaki-shi, Japan)) images. The current-voltage (J-V) characteristics of PSCs were measured with a Keithley 2400 semiconductor parameter analyzer. The measurements were conducted under AM 1.5 G 100 mW/cm2 illumination using an Oriel 150 W solar simulator. All devices were measured by masking the active area with a thin mask (0.04 cm2). The J-V characteristics for all devices were measured at a voltage scan rate of 0.1 V s−1.

3. Results and Discussion

We investigated the effect of the additives on crystallization of the CH3NH3PbI3-xClx film through XRD, as shown in Figure 2. The perovskite films were prepared on PEDOT:PSS-coated ITO glass. The samples with and without additives were annealed at 100 °C for various times. NH4I, NH4Br, and NH4Cl were used as additives. The XRD peaks of the CH3NH3PbI3-xClx film are known to occur at 14° and 28° [36], as confirmed in Figure 2a. The XRD profiles of CH3NH3PbI3-xClx without additives annealed for 1 min and 30 min, showed peaks at 13.8° and 28.0°. The samples annealed for 5 min and 10 min, showed peaks at 14.0° and 28.3°, and 14.1° and 28.4°, respectively. The sample annealed for 5 min exhibited the most intense peaks, indicating that the annealing time affected crystallization of the perovskite. The sample prepared with 0.1 M NH4I and annealed for 5 min, also showed strong peaks at 14° and 28° (Figure 2b). Figure 2c shows the XRD peaks of the perovskite film prepared using 0.3 M NH4I. Weak peaks were observed with annealing for 5 min and 30 min, but strong peaks were observed for the sample annealed at 10 min. However, the XRD peak of PbI2 was observed at 12° [41] for the samples annealed for 1 min and 10 min. The peak of PbI2 treated with 0.1 M NH4Br and 0.3 M NH4Br, is also shown in Figure 2d,e. The layers treated with NH4Cl also showed XRD peaks at 14° and 28° (Figure 2f,g). The sample treated with 0.1 M NH4Cl and annealed for 30 min exhibited a strong peak, whereas the samples annealed for 5 and 10 min exhibited a weak peak at 14°. All samples showed strong or weak peaks at 14° and 28°. Compared to, without additive, the XRD peaks of layers with additive showed strong peaks in all the layers, except for using 0.3 M NH4I and 0.3 M NH4Cl when annealed for 30 min. The layers using 0.1 M NH4I, 0.3 M NH4I, and 0.3 M NH4Cl showed a stronger peak than the layer without additive, whilst the layers using 0.1 M NH4Br, 0.3 M NH4Br, and 0.1 M NH4Cl showed weak peaks. All layers except 0.1 M NH4I showed weaker peaks than the layer without additive, when annealed for 5 min. In the case of annealing for 1 min, all layers except 0.1 M and 0.3 M NH4Cl showed a peak similar to the layer without additive. The samples treated with NH4Cl showed a stronger peak than the sample without additive. Thus, it was found that the annealing time and the additives influenced crystallization of the CH3NH3PbI3-xClx films.
Color changes in the perovskite layers were observed according to the annealing time and the additives. The CH3NH3PbI3-xClx solution was combined with different concentrations of NH4I, NH4Br, or NH4Cl as additives for spin coating. The samples were annealed at 100 °C for 1, 5, 10, or 30 min. Figure 3 shows optical images of the CH3NH3PbI3-xClx layers, before and after annealing. Before annealing, the CH3NH3PbI3-xClx films were brown, as shown in Figure 3a–c. There was only a slight difference depending on the additives. The color of the CH3NH3PbI3-xClx films changed after annealing. As shown in Figure 3d, the samples prepared with 0.1 M NH4I were nearly black regardless of the annealing time. However, those prepared with 0.3 M NH4I were red and were similar to the layers prepared with 0.3 M NH4Br (Figure 3e). After annealing the perovskite layer with 0.1 M NH4Br for 1 min, the layer became green. However, the layer with 0.1 M NH4Cl was a lighter green than that prepared with 0.1 M NH4Br and annealed for 1 min. With the use of the 0.1 M additives, the color was similar to that of the reference cells after heat treatment. Therefore, it was confirmed that a small amount of additive had no significant effect on color. However, the effect of the annealing time in the crystallization of the perovskite could be confirmed through the different color of perovskite layers, depending on the annealing time. The color of the perovskite layers treated with 0.3 M additives appeared to be affected by I−, Br−, and Cl−, respectively. The use of 0.3 M NH4Br and NH4I with 1 min of annealing produced similar color changes, whereas NH4Cl induced the formation of a greenish color. When the layers treated with 0.3 M additives were annealed for 5 min, those treated with NH4I and NH4Br were red, whereas the use of NH4Cl produced a black phase, similar in color to the perovskite layer without additives. The use of 0.3 M additives and a longer annealing time gave rise to a black phase, similar to the CH3NH3PbI3-xClx layer without additives.
The color of the CH3NH3PbI3-xClx layers, is illustrated in Figure 3. Notably, the surface quality and morphology have more influence on the performance of CH3NH3PbI3-xClx PSCs, than the color of the perovskite layer [42]. The CH3NH3PbI3-xClx films with additives were prepared on a PEDOT:PSS film. Figure 4 shows FE-SEM images of the perovskite layers annealed for different times, with different additives. When 0.1 M NH4I was added to the CH3NH3PbI3-xClx solution, the grain size increased and there were some pinholes compared to that of the sample annealed for 1 min (Figure 4a). Figure 4b shows that when 0.3 M NH4I was added, the grain size increased as the annealing time increased, and annealing for 30 min resulted in grains that were clustered with each other. As shown in Figure 4c,d, the FE-SEM images of the perovskite layer prepared with NH4Br as the additive, showed an uneven surface. Particularly, the image of the sample prepared with 0.3 M NH4Br showed a bright spot, which is estimated to be PbI2, as confirmed by XRD. When NH4Cl was used as the additive, there were many differences in the FE-SEM images depending on the concentration. Comparison of the samples prepared with 0.1 M NH4Cl (Figure 4e) and 0.3 M NH4Cl (Figure 4f), shows that there were large pinholes in the film prepared with 0.3 M NH4Cl, which is expected to have a negative effect on the perovskite layer as the light absorbing layer in solar cells.
Figure 5 shows the current density-voltage (J-V) curves of the CH3NH3PbI3-xClx PSCs with NH4I, NH4Br, and NH4Cl as additives. As a reference, a CH3NH3PbI3-xClx PSC without any additive was also fabricated, as shown in Figure 5a. The open-circuit voltage (VOC), short-circuit current (JSC), fill factor (FF), and power conversion efficiency (PCE) of the PSCs employing the films with additives, are summarized in Table 1. The perovskite layers were annealed at 100 °C for different times. The annealing times were 1, 5, 10, and 30 min. For the reference CH3NH3PbI3-xClx PSCs, the highest PCE of 5.40%, was achieved with the film annealed for 5 min. The corresponding JSC, VOC, and FF were 0.84, 9.45, and 0.68, respectively. The same PCE (4.64%) was achieved with annealing times of 10 min and 30 min. On the other hand, when the CH3NH3PbI3-xClx layer was annealed for 1 min, the JSC, VOC, FF, and PCE values declined significantly to 1.64 mA cm−2, 0.81 V, 0.15, and 0.20%, respectively. Thus, it could be deduced that the cubic perovskite was not formed when the perovskite layer was annealed for 1 min. However, the PCE of the CH3NH3PbI3-xClx PSCs employing the films with additives was higher than that of the PSCs employing the films without additives annealed for 1 min. The VOC, JSC, FF, and PCE of 0.86 V, 12.2 mA cm−2, 0.67, and 7.31%, respectively achieved using 0.1 M NH4I were significantly higher values. When 0.1 M NH4I was used as the additive and the perovskite layer was annealed for 5 min, the highest efficiency was obtained. The corresponding VOC, JSC, FF, and PCE values were 0.78 V, 16.3 mA cm−2, 0.72, and 9.13%, respectively. The PCE was 69% higher than that of the PSCs employing the perovskites without additives, under the same conditions. It was confirmed that the PCE decreased with longer heat treatment. When the concentration of NH4I was increased to 0.3 M, the PSC performance declined. Unlike the case with 0.1 M NH4I, where the highest PCE was achieved with the film annealed for 5 min, the highest PCE attained with 0.3 M NH4I was achieved with annealing for 10 min. The corresponding VOC, JSC, FF, and PCE were 0.79 V, 10.8 mA cm−2, 6.70, and 6.06%, respectively. Thus, it was confirmed that the higher the concentration of NH4I as the additive, the longer the required annealing time. The CH3NH3PbI3-xClx PSCs with the NH4Br-treated film showed remarkably low performance when 0.3 M NH4Br was added, compared to 0.1 M NH4Br. The VOC, JSC, FF, and PCE values of the PSCs employing the 0.1 M NH4Br-treated film were 0.85 V, 11.7 mA cm−2, 0.66, and 6.57%, respectively, whereas that of the PSCs with the 0.3 M NH4Br-treated films were 0.87 V, 3.09 mA cm−2, 0.23, and 0.61%, respectively, when annealing was performed for 5 min. When 0.1 M NH4Br was used as the additive, the Br− in NH4Br did not affect the CH3NH3PbI3-xClx structure significantly. However, when 0.3 M NH4Br was added, it is considered that Br− bonded with CH3NH3PbI3-xClx and disrupted the cubic structure. On the other hand, the performance parameters of the PSCs were higher when NH4I and NH4Cl were used as additives. It is considered that I− and Cl− helped to maintain the cubic structure of the perovskite. The VOC, JSC, and FF were 0.80 V, 15.1 mA cm−2, and 0.67, respectively, for the highest PCE of 8.13%, achieved with 0.1 M NH4Cl. With the use of 0.3 M NH4Cl, the VOC, JSC, FF, and PCE values were 0.67 V, 14.4 mA cm−2, 0.63, and 6.13%, respectively. The performance of the CH3NH3PbI3-xClx PSCs employing the films treated with NH4I, NH4Br, and NH4Cl as additives was investigated. The additive is related to the grain size of perovskite. As a result, the diffusion length of the active layer became longer as the grain size increased, confirming that JSC and PCE were increased. It can also be seen that a small amount of additive was more effective than a large amount. In addition, it was confirmed that the annealing time affected the characteristics of the perovskite solar cells due to the decrease in efficiency, as the annealing time became longer.

4. Conclusions

In summary, an innovative approach by adding the methylammonium halide to enhance the performance of CH3NH3PbI3-xClx PSCs was developed. CH3NH3PbI3-xClx films were fabricated for one-step coating with perovskite solution, using NH4I, NH4Br, and NH4Cl as additives. The XRD patterns and FE-SEM images of the CH3NH3PbI3-xClx films with additives generally, showed the presence of strong peaks at 14° and 28°, and an increase in the grain size of the perovskite with additives, but some pinholes were present. Investigation of the photovoltaic performance of the PSCs with additives, showed that the PCE of the CH3NH3PbI3-xClx PSCs with the 0.3 M NH4Br-treated films was lower than that of the PSCs employing films without additives. It is proposed that, Br− from NH4Br substituted the I− of CH3NH3PbI3-xClx, thereby disrupting its structure, and I− reacted with Pb+ to form PbI2, leading to a decrease in the PCE. The highest PCE of the PSCs employing the films treated with 0.1 M NH4I was 9.13%, which was 69% higher than that of the PSCs employing films without any additive. It was confirmed that small amounts of NH4I, NH4Br, and NH4Cl maintain structure and improve the properties of CH3NH3PbI3-xClx PSCs. These results indicated that the additives, especially 0.1 M NH4I, were effective in improving the characteristics of CH3NH3PbI3-xClx PSCs.

Author Contributions

Supervision, S.Y.K.; Validation, S.Y.K.; Writing—original draft, D.Y.H.; Writing—review & editing, Z.L.

Funding

This research was supported by the Bio & Medical Technology Development Program of the NRF funded by the Korean government, MSIT (2018M3A9H1023141), the Basic Research Laboratory of the NRF funded by the Korean Government (2018R1A4A1022647), and Chung-Ang University research grants in 2018.

Acknowledgments

This research was supported by the Bio & Medical Technology Development Program of the NRF funded by the Korean government, MSIT (2018M3A9H1023141), the Basic Research Laboratory of the NRF funded by the Korean Government (2018R1A4A1022647), and Chung-Ang University research grants in 2018.

Conflicts of Interest

The authors declare no conflicts of interest.

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Materials 11 01417 g001 550
Figure 1. Schematic of inverted planar perovskite solar cells (PSC) device. The PSC is composed of ITO/PEDOT:PSS/CH3NH3PbI3-xClx/PC60BM/BCP/LiF/Al. The single ITO substrate comprised four pixels and the illuminated areas of each pixel were 0.04 cm2.
Figure 1. Schematic of inverted planar perovskite solar cells (PSC) device. The PSC is composed of ITO/PEDOT:PSS/CH3NH3PbI3-xClx/PC60BM/BCP/LiF/Al. The single ITO substrate comprised four pixels and the illuminated areas of each pixel were 0.04 cm2.
Materials 11 01417 g001
Materials 11 01417 g002 550
Figure 2. XRD spectra of CH3NH3PbI3-xClx layers spin-coated on PEDOT:PSS layers. The CH3NH3PbI3-xClx solutions used for spin-coating contained (a) no additive, (b) 0.1 M NH4I, (c) 0.3 M NH4I, (d) 0.1 M NH4Br (e) 0.3 M NH4Br (f) 0.1 M NH4Cl, and (g) 0.3 M NH4Cl respectively. The samples were annealed at 100 °C for different times (1, 5, 10, 30 min).
Figure 2. XRD spectra of CH3NH3PbI3-xClx layers spin-coated on PEDOT:PSS layers. The CH3NH3PbI3-xClx solutions used for spin-coating contained (a) no additive, (b) 0.1 M NH4I, (c) 0.3 M NH4I, (d) 0.1 M NH4Br (e) 0.3 M NH4Br (f) 0.1 M NH4Cl, and (g) 0.3 M NH4Cl respectively. The samples were annealed at 100 °C for different times (1, 5, 10, 30 min).
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Materials 11 01417 g003 550
Figure 3. Optical images of CH3NH3PbI3-xClx layers prepared with (a) NH4I, (b) NH4Br, and (c) NH4Cl before annealing process and (d) NH4I, (e) NH4Br, (f) NH4Cl after annealing process. The color change occurred after annealing.
Figure 3. Optical images of CH3NH3PbI3-xClx layers prepared with (a) NH4I, (b) NH4Br, and (c) NH4Cl before annealing process and (d) NH4I, (e) NH4Br, (f) NH4Cl after annealing process. The color change occurred after annealing.
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Figure 4. FE-SEM images of CH3NH3PbI3-xClx layers coated on PEDOT:PSS layers. The CH3NH3PbI3-xClx solutions used for spin-coating contained (a) 0.1 M NH4I, (b) 0.3 M NH4I, (c) 0.1 M NH4Br, (d) 0.3 M NH4Br, (e) 0.1 M NH4Cl, and (f) 0.3 M NH4Cl, respectively. The samples were annealed at 100 °C for different times (1, 5, 10, and 30 min). The scale bar is 2 µm.
Figure 4. FE-SEM images of CH3NH3PbI3-xClx layers coated on PEDOT:PSS layers. The CH3NH3PbI3-xClx solutions used for spin-coating contained (a) 0.1 M NH4I, (b) 0.3 M NH4I, (c) 0.1 M NH4Br, (d) 0.3 M NH4Br, (e) 0.1 M NH4Cl, and (f) 0.3 M NH4Cl, respectively. The samples were annealed at 100 °C for different times (1, 5, 10, and 30 min). The scale bar is 2 µm.
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Figure 5. (a) Current density-voltage curves of CH3NH3PbI3-xClx PSCs, without any additives. The samples were annealed at 100 °C for 1, 5, 10, and 30 min, respectively. The optimal annealing time was 10 min with PCE 5.40%. Current density-voltage curves of CH3NH3PbI3-xClx PSCs with additives of (b) 0.1 M NH4I, (c) 0.3 M NH4I, (d) 0.1 M NH4Br, (e) 0.3 M NH4Br, (f) 0.1 M NH4Cl, and (g) 0.3 M NH4Cl, respectively. The maximum average PCE values of the CH3NH3PbI3-xClx PSCs with NH4I, NH4Br, and NH4Cl additives are 9.13, 6.57, and 8.13%, respectively.
Figure 5. (a) Current density-voltage curves of CH3NH3PbI3-xClx PSCs, without any additives. The samples were annealed at 100 °C for 1, 5, 10, and 30 min, respectively. The optimal annealing time was 10 min with PCE 5.40%. Current density-voltage curves of CH3NH3PbI3-xClx PSCs with additives of (b) 0.1 M NH4I, (c) 0.3 M NH4I, (d) 0.1 M NH4Br, (e) 0.3 M NH4Br, (f) 0.1 M NH4Cl, and (g) 0.3 M NH4Cl, respectively. The maximum average PCE values of the CH3NH3PbI3-xClx PSCs with NH4I, NH4Br, and NH4Cl additives are 9.13, 6.57, and 8.13%, respectively.
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Table
Table 1. Photovoltaic performance of CH3NH3PbI3-xClx PSCs with films treated with NH4I, NH4Br, and NH4Cl additives. The average values are from 20 cells for each type of device, with AM 1.5 G solar irradiation.
Table 1. Photovoltaic performance of CH3NH3PbI3-xClx PSCs with films treated with NH4I, NH4Br, and NH4Cl additives. The average values are from 20 cells for each type of device, with AM 1.5 G solar irradiation.
AdditivesAnnealing Time (min)VOC (V)JSC (mA/cm2)FFPCE (%)
NH4I, 0.1 M10.8612.20.677.31
50.7816.30.729.13
100.7516.50.668.20
300.7115.60.667.31
NH4I, 0.3 M10.867.310.623.87
50.8210.10.695.72
100.7910.80.706.06
300.7611.60.655.67
NH4Br, 0.1 M10.938.080.624.69
50.8511.70.666.57
100.7812.60.624.69
300.7313.60.636.23
NH4Br, 0.3 M10.910.910.190.15
50.873.090.230.61
100.731.290.200.19
300.530.530.180.051
NH4Cl, 0.1 M10.927.630.634.42
50.8712.90.657.30
100.8015.10.678.13
300.7514.80.687.56
NH4Cl, 0.3 M10.935.250.512.49
50.7010.20.614.36
100.6714.40.636.13
300.6413.10.605.11
No additive10.811.640.150.20
50.849.450.685.40
100.6710.80.644.64
300.7111.60.564.64

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Heo, D.Y.; Luo, Z.; Kim, S.Y. Effect of Ammonium Halide Additives on the Performance of Methyl Amine Based Perovskite Solar Cells. Materials 2018, 11, 1417. https://doi.org/10.3390/ma11081417

AMA Style

Heo DY, Luo Z, Kim SY. Effect of Ammonium Halide Additives on the Performance of Methyl Amine Based Perovskite Solar Cells. Materials. 2018; 11(8):1417. https://doi.org/10.3390/ma11081417

Chicago/Turabian Style

Heo, Do Yeon, Zhengtang Luo, and Soo Young Kim. 2018. "Effect of Ammonium Halide Additives on the Performance of Methyl Amine Based Perovskite Solar Cells" Materials 11, no. 8: 1417. https://doi.org/10.3390/ma11081417

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