A Nb-Doping TiO2 Electron Transporting Layer for Efficient Perovskite

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A Nb-Doping TiO2 Electron Transporting Layer for Efficient Perovskite Solar Cells Guannan Xiao, Chengwu Shi, Kai Lv, Chao Ying, and Yan-Qing Wang ACS Appl. Energy Mater., Just Accepted Manuscript • DOI: 10.1021/acsaem.8b00286 • Publication Date (Web): 18 May 2018 Downloaded from http://pubs.acs.org on May 18, 2018

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ACS Applied Energy Materials

A Nb-Doping TiO2 Electron Transporting Layer for Efficient Perovskite Solar Cells Guannan Xiao, Chengwu Shi*, Kai Lv, Chao Ying, Yanqing Wang School of Chemistry and Chemical Engineering, Anhui Province Key Laboratory of Advanced Catalytic Materials and Reaction Engineering, Hefei University of Technology, Hefei 230009, P. R. China

KEYWORDS: Nb-doping TiO2 electron transporting layer, TiO2 nanorod array, perovskite solar cell, electron transporting, charge separation

ABSTRACT: To improve the electron transporting and charge separation in the interface of TiO2 and perovskite, the smooth and compact Nb-doping TiO2 electron transporting layer was successfully prepared by hydrolysis-pyrolysis method using an acidic titanium isopropoxide solution in isopropanol and niobium chloride (NbCl5) as the niobium source. The planar perovskite solar cells with the un-doped TiO2 electron transporting layer gave the photoelectric conversion efficiency (PCE) of 14.56%, while the planar perovskite solar cells with the 2.5% Nb-doping TiO2 electron transporting layer obtained a PCE of 15.97%. When the TiO2 nanorod array was introduced between the 2.5% Nb-doping TiO2 electron transporting layer and the perovskite thin film, the corresponding perovskite solar cells achieved a PCE of 18.88% under illumination of simulated AM 1.5 sunlight (100 mA·cm-2). 1

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1. INTRODUCTION Perovskite solar cells have attracted much scientific interest in the field of solar energy harvesting and conversion owing to their simple structure and excellent properties.1-9 Perovskite solar cells are often comprised of a transparent conductive substrate, an electron transporting layer, a perovskite absorbing layer, a hole transporting layer and a metal electrode. And the quality of the electron transporting layer has a significant influence on the electron transporting, charge separation and charge recombination, and further affects the photoelectric conversion efficiency (PCE) of solar cells. The electron transporting layers in perovskite solar cells usually have WO3, ZnO, SnO2 and TiO2. Our group applied a WO3 ultra-thin film as the electron transporting layer to fabricate perovskite solar cells and obtained a PCE of 10.14%.10 Vedraine prepared the WO3 thin film under a low temperature of 100 °C and the PCE of the corresponding perovskite solar cells was 9.5%.11 Li and Xu assembled planar perovskite solar cells with ZnO electron transporting layer exhibiting a PCE of 14.25%.12 Vaynzof prepared Li-doping ZnO electron transporting layer and obtained a PCE of 18.02% for planar perovskite solar cells.13 Liu fabricated planar perovskite solar cells with SnO2 thin film which showed a PCE of 13.77%.14 By doping SnO2 thin film with niobium cations, Liu obtained 17.57% PCE of the corresponding perovskite solar cells.15 For TiO2 electron transporting layers, our group assembled the planar perovskite solar cells and exhibited a PCE of 12.82%. And further by introducing 200 nm length TiO2 nanorod arrays on the TiO2 electron transporting layer, the PCE was improved to 16.23%.16,17 Similarly, Li assembled 2


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200-nm length TiO2 nanorod array-based perovskite solar cells and obtained a PCE of 18.22%.18 Then the doping of metal elements and the introducing of nanorod arrays on electron transporting layers are very important to improve the photovoltaic performance of the perovskite solar cells.

In this work, the Nb-doping TiO2 electron transporting layer was successfully prepared by hydrolysis-pyrolysis method using an acidic isopropanol solution of 0.23 M titanium isopropoxide and 0.013 M HCl. Niobium chloride (NbCl5) was used as the niobium source and the molar ratio of Nb/Ti was 2.5% in the acidic isopropanol solution. To the Nb-doping TiO2 electron transporting layer, the planar perovskite solar cells gave a PCE of 15.97%, while the TiO2 nanorod array perovskite solar cells achieved a PCE of 18.88%.

2. RESULTS AND DISCUSSION 2.1 Microstructure and chemical composition of the Nb-doping TiO2 electron transporting layer Figure 1 shows the surface and cross-sectional SEM images of un-doped and 2.5% Nb-doping TiO2 electron transporting layers. It can be clearly observed that the grain size of the TiO2 nanoparticles becomes smaller after 2.5% Nb doping, which can efficiently weaken the agglomeration between the TiO2 nanoparticles, contributing to form a smoother and more compact TiO2 electron transporting layer. The smooth and compact 2.5% Nb-doping electron transporting layer can improve the electron transporting in TiO2 layer and prevent the direct contact of FTO and perovskite. When 3



the hydrothermal growth solution of TiO2 nanorod arrays was added with NbCl5 (the molar ratio of Nb/Ti = 2.5%), TiO2 nanorod arrays cannot be grown on the un-doped TiO2 electron transporting layer and Nb-doping TiO2 electron transporting layer (shown in Supporting Information). The result implied that Nb5+ had a strong suppressing effect to the growth of TiO2 nanorod arrays. Using the 2.5% Nb-doping electron transporting layer, the corresponding un-doped TiO2 nanorod array possesses the length of 300 nm, the diameter of 16 nm and the areal density of 1100 µm-2 as shown in Figure 1c,f. Compared with un-doped TiO2 electron transporting layer,16,17 there is no obvious influence of Nb5+ in 2.5% Nb-doping TiO2 electron transporting layer on the growth of un-doped TiO2 nanorod arrays.

Figure 1. Surface and cross-sectional SEM images of un-doped and 2.5% Nb-doping TiO2 electron transporting layers. (a,d) un-doped TiO2 electron transporting layers without TiO2 nanorod array, (b,e) 2.5% Nb-doping TiO2 electron transporting layers without TiO2 nanorod array, (c,f) un-doped TiO2 nanorod array on the 2.5% Nb-doping TiO2 electron transporting layers.

Figure 2 presents the XPS spectra of the Nb 3d and Ti 2p in the TiO2 electron

4


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transporting layers. The Nb 3d5/2 and Nb 3d3/2 peaks located at 207.3 eV and 210.0 eV with a peak splitting of 2.7 eV, demonstrating the presence of Nb5+ in the TiO2 electron transporting layers, which was in accordance with the literature.19,20 The Ti 2p3/2 and Ti 2p1/2 peaks of the un-doped TiO2 located at 458.9 eV and 464.5eV with a peak splitting of 5.6 eV, and the Ti 2p3/2 and Ti 2p1/2 peaks of the Nb-doping TiO2 located at 458.9 eV and 464.7 eV with a peak splitting of 5.8 eV. The Ti 2p1/2 binding energy of 2.5% Nb-doping TiO2 is slightly higher than that of un-doped TiO2, indicating that the chemical binding of Ti and O in TiO2 can be strengthened by Nb doping.

Figure 2. XPS spectra of un-doped and 2.5% Nb-doping TiO2 electron transporting layers. (a) Ti 5



2p peaks, (b) Nb 3d peaks.

2.2 Morphology, crystal phase and absorption spectra of the CH3NH3PbI3−xBrx thin films

Figure 3. CH3NH3PbI3-xBrx thin films on 2.5% Nb-doping TiO2 electron transporting layers. Surface and cross-sectional SEM images (a,c) without TiO2 nanorod array, (b,d) with TiO2 nanorod array, (e) XRD pattern, and (f) UV-Vis-NIR absorption spectra.

Figure 3 presents the surface and cross-sectional SEM images, XRD pattern, and 6


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UV–Vis absorption spectra of the CH3NH3PbI3-xBrx thin films. For the 2.5% Nb-doping electron transporting layer, the grain size of the CH3NH3PbI3-xBrx thin film on TiO2 nanorod array (~600 nm) is smaller than that of the CH3NH3PbI3-xBrx thin film without TiO2 nanorod array (~900nm), while the film thickness of the former (600 nm) is higher than that of the latter (580 nm), which is in accordance with our previous reports.16,17 According to Figure 3e, the characteristic diffraction peaks of CH3NH3PbI3-xBrx with the tetragonal perovskite structure appeared and a preferred orientation along (110) plane was observed.22,25-28 And the CH3NH3PbI3-xBrx thin film without TiO2 nanorod array had a stronger intensity than that with TiO2 nanorod array, which illustrated that the CH3NH3PbI3-xBrx thin film without TiO2 nanorod array had a better crystallinity. From Figure 3f, a red shift of the optical absorption onset was observed between the CH3NH3PbI3-xBrx thin films with and without TiO2 nanorod array, which should be attributed to the larger grain size and better crystallinity of the CH3NH3PbI3-xBrx thin film without TiO2 nanorod array.

2.3 Photovoltaic performance of perovskite solar cells The photocurrent-photovoltage characteristics and the incident photon-to-current conversion efficiency (IPCE) spectrum of the champion perovskite solar cells are shown in Figure 4, and the corresponding photovoltaic performance parameters are listed in Table 1. To the planar perovskite solar cells without TiO2 nanorod array, the open-circuit voltage (Voc) and fill factor (FF) for un-doped TiO2 electron transporting layers were 1.01±0.02 V and 0.69±0.07, and the Voc and FF for 2.5% Nb-doping TiO2

7



electron transporting layers were 0.99±0.03 V and 0.71±0.03. No obvious difference was observed. The short-circuit photocurrent density (Jsc) of 19.93±1.27 mA·cm-2 for un-doped TiO2 electron transporting layers was lower than that of 21.92±0.70 mA·cm-2 for 2.5% Nb-doping TiO2 electron transporting layers. The increase of Jsc after Nb doping should be related to the improved electron transporting and charge separation in the interface of Nb-doping TiO2/CH3NH3PbI3-xBrx as well as the fast electron injection from the CH3NH3PbI3-xBrx conduction band to the Nb-doping TiO2 conduction band.19,20,25-27 Then the PCE of 13.70±0.86% for un-doped TiO2 electron transporting layers was enhanced to the PCE of 15.69±0.53% for 2.5% Nb-doping TiO2 electron transporting layers. In other words, Nb doping in TiO2 electron transporting layers can improve the photovoltaic performance of the corresponding solar cells. Unfortunately, 5% Nb-doping will decrease the PCE of the corresponding planar perovskite solar cells as shown in Supporting Information, which may be due to the uneven TiO2 nanoparticles and rough surface of the 5% Nb-doping TiO2 electron transporting layer (shown in Supporting Information). When TiO2 nanorod arrays were grown on the Nb-doping TiO2 electron transporting layers, the Voc, Jsc, FF and PCE of the corresponding perovskite solar cells increased to 1.02±0.01 V, 23.15±0.97 mA·cm-2, 0.76±0.02 and 18.11±0.85%. The champion solar cell achieved a PCE of 18.88%， with the Voc of 1.03 V, the Jsc of 23.95 mA·cm-2 and the FF of 0.77. To the perovskite solar cells with un-doped TiO2 electron transporting layer and TiO2 nanorod array, the PCE was 16.23%.17 This result demonstrated that the Nb-doping in TiO2 electron transporting layers and the application of TiO2 nanorod 8


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arrays can improve the PCE of the corresponding perovskite solar cells. Moreover, the series resistances of the perovskite solar cells based on un-doped TiO2 electron transporting layer, 2.5% Nb-doping TiO2 electron transporting layer and 2.5% Nb-doping TiO2 electron transporting layer with TiO2 nanorod array were 11.16 Ω·cm2, 7.42 Ω·cm2 and 3.62 Ω·cm2. The FF of the corresponding perovskite solar cells were 0.70, 0.71 and 0.77. It was demonstrated that the decrease of the series resistances can increase the FF for the perovskite solar cells. From the IPCE spectra in Fig. 4(b), the integrated Jsc of the corresponding champion solar cells is 23.01 mA·cm-2, which is in close agreement with the measured value. Table 1. Photovoltaic performance parameters of perovskite solar cells with un-doped and 2.5% Nb-doping TiO2 electron transporting layers Solar cell

Voc (V)

Jsc (mA·cm-2)

FF

PCE (%)

un-doped TiO2

Champion

1.01

20.61

0.70

14.56

(without nanorod array)

Average*

1.01±0.02

19.93±1.27

0.69±0.07

13.70±0.86

2.5% Nb-doping TiO2

Champion

0.99

22.62

0.71

15.97

(without nanorod array)

Average*

0.99±0.03

21.92±0.70

0.71±0.03

15.69±0.53

2.5% Nb-doping TiO2

Champion

1.03

23.95

0.77

18.88

(with nanorod array)

Average*

1.02±0.01

23.15±0.97

0.76±0.02

18.11±0.85

*Average: 6 solar cells.

9



Figure 4. (a) Photocurrent-photovoltage characteristics and (b) IPCE spectrum of the champion perovskite solar cells.

2.4 The electron transporting and charge separation in the interface of TiO2/CH3NH3PbI3-xBrx The influence of the un-doped and 2.5% Nb-doping TiO2 electron transporting layers on the photovoltaic performance of perovskite solar cells was further investigated by analyzing the photoluminescence (PL) spectra and electrochemical impedance spectra (EIS).19,20,29-32 Figure 5a exhibits the steady-state PL spectra of CH3NH3PbI3-xBrx thin films on the un-doped TiO2 electron transporting layers without TiO2 nanorod arrays, 2.5% Nb-doping TiO2 electron transporting layers without TiO2 nanorod arrays and 2.5% Nb-doping TiO2 electron transporting layers with TiO2 nanorod arrays. From Figure 5a, the intensity at the PL peak of 764 nm decreased 10


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gradually from un-doped TiO2 electron transporting layers without TiO2 nanorod arrays to 2.5% Nb-doping TiO2 electron transporting layers without TiO2 nanorod arrays and 2.5% Nb-doping TiO2 electron transporting layers with TiO2 nanorod arrays. This result implied that the Nb-doping in TiO2 electron transporting layers and the application of TiO2 nanorod arrays can improve the electron transporting and charge separation in the interface of Nb-doping TiO2/CH3NH3PbI3-xBrx, and the electron injection from the CH3NH3PbI3-xBrx conduction band to the Nb-doping TiO2 conduction band. Figure 5b shows the Nyquist plots of the perovskite solar cells with un-doped and 2.5% Nb-doping TiO2 electron transporting layers, and the corresponding fitted data by an equivalent circuit Rs (Rct CPE) are listed in Table 2.16,17,32 To un-doped TiO2 electron transporting layers without TiO2 nanorod arrays, 2.5% Nb-doping TiO2 electron transporting layers without TiO2 nanorod arrays and 2.5% Nb-doping TiO2 electron transporting layers with TiO2 nanorod arrays, the interface transporting resistance (Rct) decreased from 1391.0 Ω to 577.0 Ω and 282.9 Ω, and the interface capacitance (Y0) also decreased from 8.15×10−8 F·sn-1 to 5.02×10−8 F·sn-1 and 2.90 ×10−8 F·sn-1. This result further demonstrated that the Nb-doping in TiO2 electron transporting layers and the application of TiO2 nanorod arrays can improve the electron transporting and charge separation in the interface of Nb-doping

TiO2/CH3NH3PbI3-xBrx,

and

the

electron

injection

from

CH3NH3PbI3-xBrx conduction band to the Nb-doping TiO2 conduction band.

11


the


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Figure 5. (a) PL spectra of CH3NH3PbI3-xBrx thin films in contact with un-doped and 2.5% Nb-doping TiO2 electron transporting layers and (b) Nyquist plots of the champion perovskite solar cells. a. 2.5% Nb-doping TiO2 electron transporting layers with TiO2 nanorod array, b. 2.5% Nb-doping TiO2 electron transporting layers without TiO2 nanorod array, c. un-doped TiO2 electron transporting layers without TiO2 nanorod array. Table 2. Parameters obtained by fitting the experimental spectra with the equivalent circuit Rs (Rct CPE). Solar cell un-doped TiO2 (without nanorod array) 2.5% Nb-doping TiO2 (without nanorod array) 2.5% Nb-doping TiO2 (with nanorod array)

Rs (Ω)

Rct (Ω)

Y0 (10−8·F·sn−1)

n

30.5

1391.0

8.15

0.97

29.5

577.0

5.02

0.95

30.9

282.9

2.90

0.98

3. CONCLUSIONS The smooth and compact 2.5% Nb-doping TiO2 electron transporting layer was 12


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successfully prepared by hydrolysis-pyrolysis method using an acidic isopropanol solution of 0.23 M titanium isopropoxide and 0.013 M HCl. NbCl5 was used as the niobium source and the molar ratio of Nb/Ti was 2.5% in the acidic isopropanol solution. The influence of the chemical composition and microstructure of TiO2 electron transporting layers on the electron transporting and charge separation in the TiO2/CH3NH3PbI3-xBrx interface were investigated. The perovskite solar cells with the 2.5% Nb-doping TiO2 electron transporting layer and TiO2 nanorod arrays exhibited a best PCE of 18.88% and an average PCE of 18.11±0.85% under illumination of simulated AM 1.5 sunlight (100 mA·cm-2).

ASSOCIATED CONTENT

Supporting Information. The following files are available free of charge. Preparation of Nb-doping TiO2 electron transporting layers; the growth of un-doped TiO2 nanorod arrays and the growth experiment of Nb-doping TiO2 nanorod arrays; solar cell fabrication and characterization; XRD patterns and UV-vis spectra of un-doped and 2.5% Nb-doping TiO2 electron transporting layers; the photovoltaic performance parameters of perovskite solar cells with 5% Nb-doping TiO2 electron transporting layers without TiO2 nanorod array; hysteresis behavior and photovoltaic performance parameters of perovskite solar cells (PDF)

AUTHOR INFORMATION Corresponding Author 13



*E-mail: [email protected], [email protected] Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT This work was financially supported by the National Natural Science Foundation of China (51472071, 51272061) and the Talent Project of Hefei University of Technology (75010-037004, 75010-037003).

REFERENCES (1) Kojima, A.; Teshima, K.; Shirai, Y.; Miyasaka, T. Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells. J. Am. Chem. Soc. 2009, 131, 6050-6051. (2) Grätzel, M. The Light and Shade of Perovskite Solar Cells. Nat. Mater. 2014, 13, 838-842. (3) Lee, M. M.; Teuscher, J.; Miyasaka, T.; Murakami, T. N.; Snaith, H. J. Efficient Hybrid Solar Cells Based on Meso-Superstructured Organometal Halide Perovskites. Science 2012, 338, 643-647. (4) Wang, Y.; Li, S.; Zhang, P.; Liu, D.; Gu, X.; Sarvari, H.; Ye, Z.; Wu, J.; Wang, Z.; Chen, Z. Solvent Annealing of PbI2 for the High-Quality Crystallization of Perovskite Films for Solar Cells with Efficiencies Exceeding 18%. Nanoscale 2016, 8, 19654-19661. (5) Xing, G.; Mathews, N.; Sun, S.; Lim, S. S.; Lam, Y. M.; Grätzel, M.; Mhaisalkar, 14


Page 14 of 20

Page 15 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


S.; Sum, T. C. Long-Range Balanced Electronand Hole-Transport Lengths in Organic-Inorganic CH3NH3PbI3. Science 2013, 342, 344-347. (6) Green, M. A.; Ho-Baillie, A.; Snaith, H. J. The Emergence of Perovskite Solar Cells. Nat. Photonics 2014, 8, 506-514. (7) Jeon, N. J.; Noh, J. H.; Kim, Y. C.; Yang, W. S.; Ryu, S.; Seok, S. I. Solvent Engineering for High-Performance Inorganic-Organic Hybrid Perovskite Solar Cells. Nat. Mater. 2014, 13, 897-903. (8) Chen, Q.; Zhou, H.; Hong, Z.; Luo, S.; Duan, H.; Wang, H.; Liu, Y.; Li, G.; Yang Y. Planar Heterojunction Perovskite Solar Cells via Vapor-Assisted Solution Process. J. Am. Chem. Soc. 2014, 136, 622-625. (9) Zuo, C.; Bolink, H. J.; Han, H.; Huang, J.; Cahen, D.; Ding, L. Advances in Perovskite Solar Cells. Adv. Sci. 2016, 3, 1500324. (10) Zhang, J.; Shi, C.; Chen, J.; Wang, Y.; Li, M. Preparation of Ultra-Thin and High-Quality WO3 Compact Layers and Comparision of WO3 and TiO2 Compact Layer Thickness in Planar Perovskite Solar Cells. J. Solid State Chem. 2016, 238, 223-228. (11) Gheno, A.; Pham, T. T. T.; Bin, C. D.; Bouclé, J.; Ratier, B.; Vedraine, S. Printable WO3 Electron Transporting Layer for Perovskite Solar Cells: Influence on Device Performance and Stability. Sol. Energ. Mat. Sol. C. 2017, 161, 347-354. (12) Guo, Y.; Kang, L.; Zhu, M.; Zhang, Y.; Li, X.; Xu, P. A Strategy toward Air-Stable and High-Performance ZnO-Based Perovskite Solar Cells Fabricated under Ambient Conditions. Chem. Eng. J. 2018, 336, 732-740. 15



(13) An, Q.; Fassl, P.; Hofstetter, Y. J.; Becker-Koch, D.; Bausch, A.; Hopkinson, P. E.; Vaynzof, Y. High Performance Planar Perovskite Solar Cells by ZnO Electron Transport Layer Engineering. Nano Energy 2017, 39, 400-408. (14) Jiang, X.; Xiong, Y.; Zhang, Z.; Rong, Y.; Mei, A.; Tian, C.; Zhang, J.; Zhang, Y.; Jin, Y.; Han, H.; Liu, Q. Efficient Hole-Conductor-Free Printable Mesoscopic Perovskite Solar Cells Based on SnO2 Compact Layer. Electrochim. Acta 2018, 263, 134-139. (15) Ren, X.; Yang, D.; Yang, Z.; Feng, J.; Zhu, X.; Niu, J.; Liu, Y.; Zhao, W.; Liu, S. F. Solution-Processed Nb:SnO2 Electron Transport Layer for Efficient Planar Perovskite Solar Cells. ACS. Appl. Mater. Inter. 2017, 9, 2421-2429. (16) Xiao, G.; Shi, C.; Zhang, Z.; Li, N.; Li, L. Short-Length and High-Density TiO2 Nanorod Arrays for the Efficient Charge Separation Interface in Perovskite Solar Cells. J. Solid State Chem. 2017, 249, 169-173. (17) Xiao, G.; Shi, C.; Li, L.; Zhang, Z.; Ma, C.; Lv, K. A 200-nm Length TiO2 Nanorod Array with a Diameter of 13 nm and Areal Density of 1100 µm-2 for Efficient Perovskite Solar Cells. Ceram. Int. 2017, 43, 12534-12539. (18) Li, X.; Dai, S. -M.; Zhu, P.; Deng, L. -L.; Xie, S. -Y.; Cui, Q.; Chen, H.; Wang, N.; Lin, H. Efficient Perovskite Solar Cells Depending on TiO2 Nanorod Arrays. ACS. Appl. Mater. Inter. 2016, 8, 21358-21365. (19) Yin, G.; Ma, J.; Jiang, H.; Li, J.; Yang, D.; Gao, F.; Zeng, J.; Liu, Z.; Liu, S. F. Enhancing Efficiency and Stability of Perovskite Solar Cells through Nb-Doping of TiO2 at Low Temperature. ACS. Appl. Mater. Inter. 2017, 9, 10752-10758. 16


Page 16 of 20

Page 17 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(20) Chen, B. -X.; Rao, H. -S.; Li, W. -G.; Xu, Y. -F.; Chen, H. -Y.; Kuang, D. -B.; Su, C. -Y. Achieving High-performance Planar Perovskite Solar Cell with Nb-Doped TiO2 Compact Layer by Enhanced Electron Injection and Efficient Charge Extraction. J. Mater. Chem. A 2016, 4, 5647-5653. (21) Wang, M.; Shi, C.; Zhang, J.; Wu, N.; Ying, C. Influence of PbCl2 Content in PbI2 Solution of DMF on the Absorption, Crystal Phase, Morphology of Lead Halide Thin Films and Photovoltaic Performance in Planar Perovskite Solar Cells. J. Solid State Chem. 2015, 231, 20-24. (22) Li, N.; Shi, C.; Li, L.; Zhang, Z.; Ma, C. Tunable Br-Doping CH3NH3PbI3-xBrx Thin Films for Efficient Planar Perovskite Solar Cells. Superlattice. Microst. 2017, 104, 445-450. (23) Li, N.; Shi, C.; Zhang, Z.; Wang, Y.; Xiao, G.; Wang, R. 130 °C CH3NH3I Treatment Temperature in Vapor-Assisted Solution Process for Large Grain and Full-Coverage Perovskite Thin Films. Opt. Mater. 2016, 60, 230-234. (24) Yu, L.; Jia, J.; Yi, G.; Hanab, M. Photoelectrochemical Properties of PbS Quantum Dot Sensitized TiO2 Nanorods Photoelectrodes. RSC. Adv. 2016, 6, 33279-33286. (25) Kim, D. H.; Han, G. S.; Seong, W. M.; Lee, J. -W.; Kim, B. J.; Park, N. -G.; Hong, K. S.; Lee, S.; Jung, H. S. Niobium Doping Effects on TiO2 Mesoscopic Electron Transport Layer-Based Perovskite Solar Cells. Chem. Sus. Chem 2015, 8, 2392-2398. (26) Yang, M.; Ding, B.; Lee, J. -K. Surface Electrochemical Properties of 17



Niobium-doped Titanium Dioxide Nanorods and Their Effect on Carrier Collection Efficiency of Dye Sensitized Solar Cells. J. Power Sources 2014, 245, 301-307. (27) Noh, J. H.; Lee, S.; Kim, J. Y.; Lee, J. -K.; Han, H. S.; Cho, C. M.; Cho, I. S.; Jung, H. S.; Hong, K. S. Functional Multilayered Transparent Conducting Oxide Thin Films for Photovoltaic Devices. J. Phys. Chem. C 2009, 113, 1083-1087. (28) Ying, C.; Shi, C.; Wu, N.; Zhang, J.; Wang, M. A Two-Layer Structured PbI2 Thin Film for Efficient Planar Perovskite Solar Cells. Nanoscale 2015, 7, 12092-12095. (29) Liu, C.; Qiu, Z.; Meng, W.; Chen, J.; Qi, J.; Dong, C.; Wang, M. Effects of Interfacial Characteristics on Photovoltaic Performance in CH3NH3PbBr3-based Bulk Perovskite Solar Cells with Core/Shell Nanoarray as Electron Transporter. Nano Energy 2015, 12, 59-68. (30) Mora-Seró, I.; Bisquert, J.; Fabregat-Santiago, F.; Garcia-Belmonte, G.; Zoppi, G.; Durose, K.; Proskuryakov, Y.; Oja, I.; Belaidi, A.; Dittrich, T.; Tena-Zaera, R.; Katty, A.; Lévy-Clément, C.; Barrioz, V.; Irvine, S. J. C. Implications of the Negative Capacitance Observed at Forward Bias in Nanocomposite and Polycrystalline Solar Cells. Nano Lett., 2006, 6, 640-650. (31) Dualeh, A.; Moehl, T.; Tétreault, N.; Teuscher, J.; Gao, P.; Nazeeruddin, M. K.; Grätzel, M. Impedance Spectroscopic Analysis of Lead Iodide Perovskite-Sensitized Solid-State Solar Cells. ACS Nano 2014, 8, 362-373. (32) Zhang, Y.; Shi, C.; Dai, X.; Liu, F.; Fang, X.; Zhu, J. Pyrolysis Preparation of Cu2ZnSnS4 Thin Film and Its Application Tocounter Electrode in Quantum 18


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Dot-Sensitized Solar Cells. Electrochim. Acta 2014, 118, 41-44.

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A Nb-Doping TiO2 Electron Transporting Layer for Efficient Perovskite

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