Efficient Colorful Perovskite Solar Cells Using a Top Polymer

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Efficient colorful perovskite solar cells using a top polymer electrode simultaneously as spectrally selective antireflection coating Youyu Jiang, Bangwu Luo, Fangyuan Jiang, Fuben Jiang, Canek Fuentes-Hernandez, Tiefeng Liu, Lin Mao, Sixing Xiong, Zaifang Li, Tao Wang, Bernard Kippelen, and Yinhua Zhou Nano Lett., Just Accepted Manuscript • DOI: 10.1021/acs.nanolett.6b04019 • Publication Date (Web): 23 Nov 2016 Downloaded from http://pubs.acs.org on November 24, 2016

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Efficient colorful perovskite solar cells using a top polymer electrode simultaneously as spectrally selective antireflection coating Youyu Jiang,⊥† Bangwu Luo,⊥† Fangyuan Jiang,⊥† Fuben Jiang,‡ Canek Fuentes-Hernandez,§ Tiefeng Liu,† Lin Mao,† Sixing Xiong,† Zaifang Li,† Tao Wang,‡ Bernard Kippelen,§ and Yinhua Zhou*†

†

Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information,

Huazhong University of Science and Technology, Wuhan, Hubei, 430074, P. R. China,

‡

State

Key Laboratory of Silicate Materials for Architectures, School of Materials Science and Engineering, Wuhan University of Technology, Wuhan, Hubei, 430070, P. R. China, §Center for Organic Photonics and Electronics (COPE), School of Electrical and Computer Engineering Georgia Institute of Technology, Atlanta, Georgia 30332, United States.

KEYWORDS: perovskite solar cells, colorful, antireflection coating, conducting polymer, building integrated photovoltaics

1 Environment ACS Paragon Plus

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ABSTRACT: Organometal halide perovskites have shown excellent optoelectronic properties and used to demonstrate a variety of semiconductor devices. Colorful solar cells are desirable for photovoltaic integration in buildings and other aesthetically appealing applications. However, the realization of colorful perovskite solar cells is challenging because of their broad and large absorption coefficient that commonly leads to cells with dark-brown colors. Herein, for the first time, we report a simple and efficient strategy to achieve colorful perovskite solar cells by using the transparent conducting polymer (poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), PEDOT:PSS) as a top electrode and simultaneously as an spectrally-selective antireflection coating. Vivid colors across the visible spectrum are attained by engineering optical interference effects among the transparent PEDOT:PSS polymer electrode, the hole-transporting layer and the perovskite layer. The colored perovskite solar cells display power conversion efficiency values from 12.8 to 15.1% (from red to blue) when illuminated from the FTO glass side, and from 11.6 to 13.8% (from red to blue) when illuminated from the PEDOT:PSS side. The new approach provides an advanced solution for fabricating colorful perovskite solar cells with easy processing and high efficiency.


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Organometal halide perovskites have shown excellent optoelectronic properties including direct bandgap, large absorption coefficients, low exciton binding energy, long carrier diffusion length, high charge carrier mobility and easy-film fabrication.1-10 They have been demonstrated in various semiconductor devices including solar cells,11-16 light-emitting diodes,17-19 laser devices,20-21 photodetectors,22-23 and ferroelectric devices.24 Particularly, organometal halide perovskite-based solar cells have yielded a power conversion efficiency (PCE) value up to 22.1% that exceeds that of multicrystalline silicon solar cells and is comparable to that of other thin-film solar cells (such as those based on CdTe and CuInGaSe).25 As the technology of solar cells continues to mature, it is desirable to develop cells with aesthetic properties (i.e., either transmission or reflection) to make them suitable for building integration26 and other applications27-28 (such as wearable electronics). Unfortunately, highperformance solar cells appear preferably black to maximize optical absorption over the entire visible part of the optical spectrum and consequently high PCE. This, imposes an inherent tradeoff between the color and the performance of the solar cell. Hence, high performance perovskite solar cells (including CH3NH3PbI3-based or NH2CH=NH2PbI3-based) generally display dark brown hues, making them less attractive for applications where the aesthetic of a device is important. To improve the aesthetic of perovskite solar cells, two main approaches have been used: (1) bandgap engineering; and (2) use of nanostructures with engineered optical properties. For instance, colorful perovskite solar cells, with a color gamut limited to yellow and red hues, have


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been demonstrated using bandgap engineering by tuning the iodine (I) to bromine (Br) ratio.29-31 However, bandgap engineering approaches necessarily lead to reduced PCE values due to the decreased absorption across the visible spectral range. Another approach of tuning optical properties is to incorporate engineered optical structures.32-36 Optical microcavities and photonic crystals have been used to demonstrate colored organic solar cells.37-40 These strategies have been shown effective for colored perovskite solar cells.41-43 For example, Zhang et al.41 pioneered the demonstration of colorful perovskite solar cells through the use of TiO2/SiO2 onedimensional photonic crystal structures, consisting of 5-7 cycles of TiO2/SiO2 alternating layers. The use of a photonic crystal provides a wide tunability of reflectance (R) spectra but also adds fabrication complexity and results in solar cells that display PCE values ranging from 4.5% to 8.8%. Colored semitransparent perovskite cells have also been demonstrated through the use of microcavities (e.g., Ag/WO3/PTCBI/Ag, Ag/ITO/Ag, etc.) and where the perovskite active layer was thin enough (ca. 100 nm) to increase the transmittance (T) of the device. However, this approach sacrifices the absorption in the perovskite layer and results in devices with PCE values of 4 to 8%.43-44 Recently, Deng et al. reported a new type of colorful perovskite solar cells using a nanostructured perovskite active layer that acts as both an absorber and a reflection grating.45 The cells displayed a power conversion efficiency of 12.2%, but the resulting devices displayed a wide variety of reflective hues (i.e., a heterogeneous mixture of colors, instead of a single color). The color of a solar cell is a result of the combined spectral response of the eye, the emission spectra of a light source (e.g. the sun) and the transmittance or reflectance spectra of the solar


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cell. To optimize the performance of a solar cell, the transmittance and the reflectance of the solar cell have to be minimized. However, when small reflectance losses can be tolerated, the spectra of the reflected light can be modulated through interference effects arising from the coherent superposition of the reflected and transmitted electromagnetic fields generated at the multiple interfaces existing in the solar cell geometry. The tailored reflectance therefore produces aesthetically pleasing colorful solar cell devices. In this work, we report on a simple, and yet general and effective, approach to achieve highefficiency colorful perovskite solar cells without adding extra layers or fabrication complexity to the device structure. In our approach the reflective electrode (typically Au in perovskite solar cells) of a solar cell is replaced by a transparent polymer electrode comprising the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), while FTO acts as a transparent bottom electrode, as shown in Figure 1a. A cross-sectional image of a fabricated cell is shown in Figure S1. The conducting polymer layer is engineered to act as both top electrode and antireflection coating. Control over the thickness of the PEDOT:PSS layer (either by controlling the parameters during spin-coating or by depositing different number of layers of PEDOT:PSS with a given thickness via transfer-printing technique,46-47 herein denoted PEDOT:PSST) results in the suppression of the reflectance at a specific wavelength and the selective reflection of other wavelengths. As a consequence, this simple approach results in aesthetical perovskite solar cells with PCE values from 11 to 15% (depending on the color of the cells) and a wide color gamut (e.g., red, orange, green, blue, purple, etc.) as shown in the


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photograph displayed in Figure 1b, wherein 126 perovskite solar cells are placed next to one another to create the letter “H”. Mechanism of color generation. The reflectance, R, of a multilayer structure can be calculated by the reflection coefficient (i.e. the complex amplitude of the reflected electromagnetic wave) which is given by the generalized Airy formulas as:35, 48

R =r=

r12 + r23...n e −2iφ2 1 + r12 r23...n e−2iφ2

(1)

where r23... j =

r23 + r34... j e −2 iφ3 1 + r23 r34... j e−2iφ3

rj , j +1 = kj =

k j − k j +1 k j + k j +1

2π

λ

,

,

n j cos(θ j ),

φ j = k jt j , and nj, kj, θj and tj are the complex refractive index, extinction coefficient, angle of incidence and thickness of the jth layer. Hence, in a perovskite solar cell with the device structure depicted in Figure 1a, the necessary condition for the PEDOT:PSS layer to act as an antireflection coating is that:

rair PEDOT :PSS = rSolarCell e−2iφPEDOT:PSS ,

(2)

where rsolar cell is the reflection coefficient that arises by considering all the interfaces in the entire perovskite solar cell, starting with the PEDOT:PSS/HTL interface and ending with the substrate (i.e. glass)/air interface. It should be noted that since the photoactive layer (i.e. perovskite) of a solar cell displays strong absorption bands across the visible spectral range, the Airy formula can


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rSolarCell ≈ be truncated at the active layer (AL), such that

rPEDOT :PSS HTL + rHTL AL e −2iφHTL 1 + rPEDOT :PSS HTL rHTL AL e −2iφHTL

could be used

as a good approximation. Hence, in an optimized perovskite solar cell, the material and thickness selection of the HTL, along with the thickness of the transparent electrode are the parameters that could be controlled to minimize the reflectance according to equation (2). More importantly, equation (2) also shows the mechanism whereby the top reflectance of a device can be minimized by selecting a PEDOT:PSS layer of adequate thickness and that this effect is periodic on the value of φPEDOT :PSS , modulus 2π. Optical modeling and color demonstration of solar cells. To investigate this approach for the realization of colored perovskite solar cells, we first derived the refractive index values of the different materials used by fitting transmittance and spectroscopic ellipsometric data, using the software CompleteEASE® J.A. Woollam Co.. Ellipsometric data was acquired from independent samples comprising single layers of the materials on glass/FTO substrates by using a M-2000 J.A. Woollam Co. spectroscopic ellipsometer. Figure 2a-2d display the refractive index (n) and extinction coefficient (k) values for CH3NH3PbI3-xClx perovskite film, PEDOT:PSST film, SpiroOMeTAD HTL film, and P3HT HTL film (note that: Spiro-OMeTAD HTL and P3HT HTL are both Li-TFSI and t-BP doped as shown in the Methods part), the complex refractive index values for FTO, c-TiO2 and m-TiO2 are shown in the supporting information (Figure S2) for completeness. Figure 2e and 2f displays the calculated reflectance spectra, using the software CompleteEASE®, of perovskite solar cells with the structure of glass/FTO/c-TiO2/m-


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TiO2/CH3NH3PbI3-xClx/HTL/PEDOT:PSST as a function of the thickness of PEDOT:PSST electrode and for devices having either doped Spiro-OMeTAD or doped P3HT as the HTL. These data clearly shows the variation of the spectral position of the reflectance of a solar cell by varying the thickness of the PEDOT:PSST layer for devices having different HTLs. Next, we fabricated colorful perovskite solar cells with the simulated device structure. In this case, PEDOT:PSST with thickness values in the range between 40 and 160 nm were transferprinted using PDMS as the transfer medium. Figure 3a and Figure S3 confirms the effectiveness of the approach in tuning the reflectance of the devices by simply changing the thickness of the PEDOT:PSST layer, either by direct transfer-printing layers with different thickness values or by stacking different numbers of layers of the same thickness on a single device (i.e., 1 to 4 layers of 48 nm-thick PEDOT:PSST films stacked on a cell device by layer-by-layer transfer-printing). Figure 3b displays a comparison between simulated versus measured reflectance spectra in solar cells having a Spiro-OMeTAD HTL with 3 different thickness values of PEDOT:PSST. Reflectance spectra of more cells with different thicknesses of PEDOT:PSST electrodes are shown in Figure S4a (for devices with Spiro-OMeTAD HTL) and Figure S4b (for devices with P3HT HTL). The good agreement between simulated and measured reflectance values confirms that the spectral position of the reflectance of a cell can be effectively tuned by varying the thickness of the PEDOT:PSST layer. Consequently, the reflectance spectra of perovskite cells can be tuned to produce colorful devices with hues across the visible spectral range. The spectral distribution of the reflectance spectra gives rise to different color hues that can be described


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using the CIE 1931 color space. Figure 3c shows measured CIE color coordinates of devices having Spiro-OMeTAD and P3HT HTLs. Despite the simplicity of this approach, a wide color gamut is achieved in both cases. Photovoltaic performance of colorful solar cells. First, we investigated the optical and electrical properties of the PEDOT:PSST top electrode. Figure S5 shows the sheet resistance, conductivity and transmittance of the transfer-printed PEDOT:PSST electrode with different thicknesses (48, 95, 160 nm). The 48-nm PEDOT:PSST film displays a sheet resistance of 347 ± 20 Ω/sq and the transmittance of around 90%. For the 160-nm PEDOT:PSST film, the sheet resistance is 107 ± 10 Ω/sq and the transmittance is about 80% in the visible region. The calculated conductivity is 600 ± 50 S/cm which is not dependent on the film thickness. The work function of the PEDOT:PSST was measured to be 5.0 eV by Kelvin probe. It is close to the highest occupied molecular orbital (HOMO) level (-5.22 eV)11 of Spiro-OMeTAD which enables the efficient hole collection by the PEDOT:PSST electrode. Figure 4a shows the current-voltage (J-V) curves of the colored devices with SpiroOMeTAD HTL. Their photovoltaic parameters are summarized in Table 1. Because FTO and PEDOT:PSST are used as the bottom and the top electrodes in the cells, respectively. Figure S6 shows transmittance of the colored cells with PEDOT:PSST of 48, 95, and 160 nm. The cells display the average visible transmittance (AVT) around 10% in the spectral range of 400-750 nm (Table S1). For the photovotlaic performance, when illuminated from the FTO side, all colored solar cells with PEDOT:PSST thickness of 75, 95, 105, 160 nm exhibit comparable PCE values


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in the range between 15 and 16%. These cells exhibit similar open-circuit voltage (VOC) of 1.11 V, short-circuit current density (JSC) of about 19 mA/cm2, fill factor of about 0.71. For the cell with a 48 nm-thick PEDOT:PSST layer, it displays similar JSC and external quantum efficiency (EQE) (Figure 4a and 4c) to those cells with thicker PEDOT:PSST layer, but slightly lower FF (0.63) that could be caused by a larger series resistance (smaller slope at VOC in Fig. 4a) due to the larger sheet resistance of PEDOT:PSST electrode (Figure S5). For comparison, we have also fabricated reference cells with vacuum-evaporated Au electrode that exhibits VOC of 1.10 V, JSC of 20.6 mA/cm2, FF of 0.76, and PCE of 17.3% (Figure S7). The metal electrode Au can provide a reflective surface that allows the perovskite film absorbs the light residue after the first pass, thus yielding higher JSC and PCE than the cells with PEDOT:PSST electrode. Comparing to the reference cell, the FF of the cells with PEDOT:PSST electrodes is slightly lower (Table 1). It should be noted the FF of cells isn’t significantly influenced by the sheet resistance of the electrode when device area is small (about 10 mm2) that is consistent to the previous reports,49-50 but the influence of the sheet resistance might become more pronounced when device area becomes larger. When illuminated from the top PEDOT:PSST side, perovskite solar cells display PCE values of 11.6, 13.8 and 11.6% for cells with PEDOT:PSST thickness of 48, 95 and 160 nm, respectively. These PCE values are lower than those when illuminated from FTO side. The main difference is the JSC. The lower JSC can be further analyzed from the EQE spectra (Figure 4c and 4d). The cells display lower EQE values in the range from ca. 330 to 430 nm and 500 to 750 nm


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when illuminated from the PEDOT:PSST side as compared when illuminated from the FTO side. The lower EQE in the range of ca. 330 to 430 nm is explained by the strong absorption of SpiroOMeTAD for wavelengths smaller than 430 nm,51 while the lower EQE in the spectral range of 500 to 750 nm is due to the reflectance loss and absorption of PEDOT:PSST electrode. For cells with different colors, the EQE spectra also differ when illuminated from the PEDOT:PSST side because of synergistic effect of the varied reflectance loss and absorption of the PEDOT:PSS of different thickness. The cell with 160-nm PEDOT:PSST displays lowest EQE at the 500-750 nm and yields a lowest JSC of 14.1 mA/cm2. For the cells with P3HT HTL, the PCE is about 10% as shown in Figure S8 and Table S2. Hysteresis is a general issue for perovskite solar cells and consequently it is also exhibited by these colored cells with Spiro-OMeTAD HTL (Figure S9, 95 nm PEDOT:PSST). The stabilized output power is thus measured to determine the efficiency under the maximum power point of 0.88 V. The insets of the Figure 4a and Figure 4b display steady photocurrents of 16.3 mA/cm2 when illuminated from FTO side and 14.7 mA/cm2 when illuminated from PEDOT:PSST side, thus providing stable PCEs of 14.3% and 12.9%, respectively. The long-term stability of a bluecolored cell with 95 nm PEDOT:PSST electrode has been preliminary evaluated by keeping the cell in the dark in the N2-filled glove box or exposed to air. Figure S10 shows the J-V characteristics after kept for different time. The cell performance remains about 90% of initial PCE value after kept in inert atmosphere for 30 days. That means the cells can be stable if the


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cell is well encapsulated. When the cell was exposed to air (relative humility of 20%) without encapsulation, the cell performance becomes 68% after 5 days (Figure S10 and Table S3). In summary, we have demonstrated a novel strategy to realize colorful perovskite solar cells based on a device structure wherein a transparent conducting polymer PEDOT:PSST top electrode simultaneously serves as an antireflection coating. Modification of the PEDOT:PSST thickness and selection of HTL allows tuning the reflectance spectra and gives rise to colorful perovskite solar cells with a wide color gamut. Vivid colors arises from the coherent superposition of the reflected and transmitted electromagnetic fields among the transparent PEDOT:PSS polymer electrode, the hole-transporting layer and the perovskite layer. It should be noted that PEDOT:PSST role of antireflection refers to that its thickness variation results in the suppression of the reflectance at a specific wavelength, rather than the whole visible spectral wavelength. The PEDOT:PSST layer contributes as a reflection-modulating layer with the mechanism of the antireflection coating. The different colors of the cells are observed from the PEDOT:PSST electrode side. When see from the FTO side, the cells are typically dark-brown even with different thicknesses of PEDOT:PSST electrodes. For perovskite solar cells with typical structure including thick metal electrodes, the colors are not able to be realized. That is because the thick metal electrodes are highly reflective, not transmissive and therefore, the optical interference doesn’t exist among the reflected and transmitted electromagnetic fields from different interfaces.


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Use of semitransparent PEDOT:PSS top electrode, instead of commonly used Au, is not only more economical but also results in cells that can be illuminated from either side and can therefore be used as architectural elements that could capture indoor and outdoor light. The power conversion efficiency of these colorful perovskite cells can reach up to 15% and 13% when illuminated from FTO side and the polymer electrode side respectively. The general nature of the interference effects arising between a first layer with a large refractive index (e.g., due to the presence of absorption bands) and one with a lower refractive index, should be applicable to other types of thin-film solar cells. Therefore, we believe that this approach holds great promise to realize colorful thin-film solar cells for a variety of integration applications with buildings, electric vehicles, and wearable electronics, etc.


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ASSOCIATED CONTENT Supporting Information. Additional photographic images of colorful devices, reflection spectra, and J-V curves of the solar cells. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Author *E-mail: [email protected] Author Contributions Y.Y.J., B.W.L. and Y.H.Z. conceived the idea of the project. Y.Y.J., F.Y.J, B.W.L., T.F.L and L.M. performed the device fabrication and characterization. S.X.X. and Z.F.L. optimized the polymer electrodes. F.B.J. performed the ellipsometry measurements. C.F-H. performed the optical modeling. Y.H.Z., T.W. and B.K. directed this work. Y.Y.J., C.F-H. and Y.H.Z. co-wrote the manuscript. All authors discussed the results and contributed to the final version of the manuscript. Notes The authors declare no competing financial interest.

ACKNOWLEDGMENTS The work is supported by the Recruitment Program of Global Youth Experts, the National Hightech R&D Program of China (863 Program, No. 2015AA034601), the National Natural Science


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Foundation of China (Grant No. 21474035, 21504065), and Technology Creative Project of Excellent Middle & Young Team of Hubei Province (No. T201511). CFH and BK acknowledge support from by the US Department of the Navy, Office of Naval Research Award No. N0001414-1-0580 and N00014-16-1-2520, through the MURI Center CAOP, Office of Naval Research Award N00014-04-1-0313 and by the US Department of Energy through the Bay Area Photovoltaic Consortium under Award Number DE-EE0004946.

REFERENCES ( 1)

Burschka, J.; Pellet, N.; Moon, S.-J.; Humphry-Baker, R.; Gao, P.; Nazeeruddin, M. K.; Grätzel, M. Nature 2013, 499, 316-319.

( 2)

Green, M. A.; Ho-Baillie, A.; & Snaith, H. J. Nat. Photonics 2014, 8, 506-514.

( 3)

Dong, Q.; Fang, Y.; Shao, Y.; Mulligan, P.; Qiu, J.; Cao, L.; Huang, J. Science 2015, 347, 967-970.

( 4)

Miyata, A.; Mitioglu, A.; Plochocka, P.; Portugall, O.; Wang, J. T.-W.; Stranks, S. D.; Snaith, H. J.; Nicholas, R. J. Nat. Phys. 2015, 11, 582-587.

( 5)

Lin, Q.; Armin, A.; Nagiri, R. C. R.; Burn, P. L.; Meredith, P. Nat. Photonics 2015, 9, 106-112.

( 6)

Stranks, S. D.; Eperon, G. E.; Grancini, G.; Menelaou, C.; Alcocer, M. J. P.; Leijtens, T.; Herz, L. M.; Petrozza, A.; Snaith, H. J. Science 2013, 342, 341-344.

( 7)

Docampo, P.; Bein, T. Acc. Chem. Res. 2016, 49, 339-346.


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( 8)

Page 16 of 25

Brenner, T. M.; Egger, D. A.; Kronik, L.; Hodes, G.; Cahen, D. Nat. Rev. Mater. 2016, 1, 15007.

( 9)

Kim, H.; Lim, K.-G.; Lee, T.-W. Energy Environ. Sci. 2016, 9, 12-30.

( 10) Lim, K.-G.; Kim, H.-B.; Jeong, J.; Kim, H.; Kim, J. Y.; Lee, T.-W. Adv. Mater. 2014, 26, 6461-6466. ( 11) Kim, H.-S.; Lee, C.-R.; Im, J.-H.; Lee, K.-B.; Moehl, T.; Marchioro, A.; Moon, S.-J.; Humphry-Baker, R.; Yum, J.-H.; Moser, J. E.; Grätzel, M.; Park, N.-G. Sci. Rep. 2012, 2, 591. ( 12) Yang, W. S.; Noh, J. H.; Jeon, N. J.; Kim, Y. C.; Ryu, S.; Seo, J.; Seok, S. I. Science 2015, 348, 1234-1237. ( 13) Zhou, H.; Chen, Q.; Li, G.; Luo, S.; Song, T.-b.; Duan, H.-S.; Hong, Z.; You, J.; Liu, Y.; Yang, Y. Science 2014, 345, 542-546. ( 14) Lee, J.-W.; Kim, H.-S.; Park, N.-G. Acc. Chem. Res. 2016, 49, 311-319. ( 15) Lim, K.-G.; Ahn, S.; Kim, Y.-H.; Qi, Y.; Lee, T.-W. Energy Environ. Sci. 2016, 9, 932939. ( 16) Lim, K.-G.; Ahn, S.; Kim, H.; Choi, M.-R.; Huh, D. H.; Lee, T.-W. Adv. Mater. Interfaces 2016, 3, 1500678. ( 17) Tan, Z.-K.; Moghaddam, R. S.; Lai, M. L.; Docampo, P.; Higler, R.; Deschler, F.; Price, M.; Sadhanala, A.; Pazos, L. M.; Credgington, D.; Hanusch, F.; Bein, T.; Snaith, H. J.; Friend, R. H. Nat. Nanotechnol. 2014, 9, 687-692.


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( 18) Stranks, S. D.; Snaith, H. J. Nat. Nanotechnol. 2015, 10, 391-402. ( 19) Cho, H.; Jeong, S.-H.; Park, M.-H.; Kim, Y.-H.; Wolf, C.; Lee, C.-L.; Heo, J. H.; Sadhanala, A.; Myoung, N.; Yoo, S.; Im, S. H.; Friend, R. H.; Lee, T.-W. Science 2015, 350, 1222-1225. ( 20) Zhu, H.; Fu, Y.; Meng, F.; Wu, X.; Gong, Z.; Ding, Q.; Gustafsson, M. V.; Trinh, M. T.; Jin, S.; Zhu, X. Y. Nat. Mater. 2015, 14, 636-642. ( 21) Liu, X.; Niu, L.; Wu, C.; Cong, C.; Wang, H.; Zeng, Q.; He, H.; Fu, Q.; Fu, W.; Yu, T.; Jin, C.; Liu, Z.; Sum, T. C. Adv. Sci. 2016, DOI: 10.1002/advs.201600137. ( 22) Dou, L.; Yang, Y.; You, J.; Hong, Z.; Chang, W.-H.; Li, G.; Yang, Y. Nat. Commun. 2014, , 5404. ( 23) Lin, Q.; Armin, A.; Burn, P. L.; Meredith, P. Nat. Photonics. 2015, 9, 687-694. ( 24) Zhang, C.; Sun, D.; Sheng, C. X.; Zhai, Y. X.; Mielczarek, K.; Zakhidov, A.; Vardeny, Z. V. Nat. Phys. 2015, 11, 427-434. ( 25) National

Renewable

Energy

Labs

(NREL)

Efficiency

Chart

2016,

http://www.nrel.gov/pv/assets/images/efficiency_chart.jpg (accessed Nov. 2016 ). ( 26) Henemann, A. Renewable Energy Focus 2008, 9, 14-19. ( 27) Richardson, D. B. Renewable Sustainable Energy Rev. 2013, 19, 247-254. ( 28) Schubert, M. B.; Werner, J. H. Mater. Today 2006, 9, 42-50. ( 29) Eperon, G. E.; Stranks, S. D.; Menelaou, C.; Johnston, M. B.; Herz, L. M.; Snaith, H. J. Energy Environ. Sci. 2014, 7, 982-988.


Nano Letters

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( 30) Cui, D.; Yang, Z.; Yang, D.; Ren, X.; Liu, Y.; Wei, Q.; Fan, H.; Zeng, J.; Liu, S. J. Phys. Chem. C 2016, 120, 42-47. ( 31) Noh, J. H.; Im, S. H.; Heo, J. H.; Mandal, T. N.; Seok, S. I. Nano Lett. 2013, 13, 17641769. ( 32) Gu, Y.; Zhang, L.; Yang, J. K. W.; Yeo, S. P.; Qiu, C.-W.. Nanoscale 2015, 7, 6409-6419. ( 33) Raut, H. K.; Ganesh, V. A.; Nair, A. S.; Ramakrishna, S. Energy Environ. Sci. 2011, 4, 3779-3804. ( 34) Li, X.; Yu, X.; Han, Y. J. Mater. Chem. C 2013, 1, 2266-2285. ( 35) Kats, M. A.; Blanchard, R.; Genevet, P.; Capasso, F. Nat. Mater. 2013, 12, 20-24. ( 36) Xue, J.; Zhou, Z.-K.; Wei, Z.; Su, R.; Lai, J.; Li, J.; Li, C.; Zhang, T.; Wang, X.-H. Nat. Commun. 2015, 6, 8906. ( 37) Park, H. J.; Xu, T.; Lee, J. Y.; Ledbetter, A.; Guo, L. J. ACS Nano 2011, 5, 7055-7060. ( 38) Betancur, R.; Romero-Gomez, P.; Martinez-Otero, A.; Elias, X.; Maymo, M.; Martorell, J. Nat. Photon. 2013, 7, 995-1000. ( 39) Chen, Y.-H.; Chen, C.-W.; Huang, Z.-Y.; Lin, W.-C.; Lin, L.-Y.; Lin, F.; Wong, K.-T.; Lin, H.-W. Adv. Mater. 2014, 26, 1129-1134. ( 40) Lee, J. Y.; Lee, K.-T.; Seo, S.; Guo, L. J. Sci. Rep. 2014, 4, 4192. ( 41) Zhang, W.; Anaya, M.; Lozano, G.; Calvo, M. E.; Johnston, M. B.; Míguez, H.; Snaith, H. J. Nano Lett. 2015, 15, 1698-1702.


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Nano Letters

( 42) Ramírez Quiroz, C. O.; Bronnbauer, C.; Levchuk, I.; Hou, Y.; Brabec, C. J.; Forberich, K. ACS Nano 2016, 10, 5104-5112. ( 43) Lee, K.-T.; Fukuda, M.; Joglekar, S.; Guo, L. J. J. Mater. Chem. C 2015, 3, 5377-5382. ( 44) Lu, J.-H.; Yu, Y.-L.; Chuang, S.-R.; Yeh, C.-H.; Chen, C.-P. J. Phys. Chem. C 2016, 120, 4233-4239. ( 45) Deng, Y.; Wang, Q.; Yuan, Y.; Huang, J. Mater. Horiz. 2015, 2, 578-583. ( 46) Tong, J.; Xiong, S.; Zhou, Y.; Mao, L.; Min, X.; Li, Z.; Jiang, F.; Meng, W.; Qin, F.; Liu, T.; Ge, R.; Fuentes-Hernandez, C.; Kippelen, B.; Zhou, Y. Mater. Horiz. 2016, 3, 452-459. ( 47) Jiang, F.; Liu, T.; Zeng, S.; Zhao, Q.; Min, X.; Li, Z.; Tong, J.; Meng, W.; Xiong, S.; Zhou, Y. Opt. Express 2015, 23, A83-A91. ( 48) Born, M.; Wolf, E. Principles of Optics 7th edn (Cambridge Univ. Press, Cambridge, UK, 2003). ( 49) You, P.; Liu, Z.; Tai, Q.; Liu, S.; Yan, F. Adv. Mater. 2015, 27, 3632-3638. ( 50) Bu, L.; Liu, Z.; Zhang, M.; Li, W.; Zhu, A.; Cai, F.; Zhao, Z.; Zhou, Y. ACS Appl. Mater. Interfaces 2015, 7, 17776-17781. ( 51) Plass, R.; Pelet, S.; Krueger, J.; Grätzel, M.; Bach, U. J. Phys. Chem. B 2002, 106, 75787580.


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Figures and Tables

Figure 1. (a) Device architecture of the cells with conducting polymer PEDOT:PSST as the top electrode where the PEDOT:PSST means the PEDOT:PSS electrode was prepared by transfer printing. (b) Photographic image of a colored schematic “H” assembled by colorful perovskite solar cells. Each pixel substrate is with the size of about 5 × 5 mm2.


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(b)

5

2.0

(c)

Perovskite 4

(d) 3

2.0

PEDOT:PSS 1.5

1.0

Spiro-OMeTAD

0.4

P3HT 0.8 1.5

1.5 2

k n

0.4 1

0.5

1

0.5

0.2

0.5

1

1.0

k n

n

0.2

1.0

k

1.0 2

2

0.6

3

0.0 0.0

0.0 400

600

800

0.0

1000

Wavelength (nm)

0

400

500

600

700

800

(f)

800 0.19 0.18 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0

Wavelength (nm)

750 700 650 600 550 500 450

600

800

1000

0

0.0 400

500

600

700

800

Wavelength (nm)

Wavelength (nm)

Wavelength (nm)

(e)

400

800 750

0.32 0.29 0.26 0.22 0.19 0.16 0.13 0.096 0.064 0.032 0

700

Wavelength (nm)

0

2.0

3

k

(a)

n

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

Nano Letters

650 600 550 500 450 400 350

400 50

100

150 T

200

250

PEDOT:PSS thickness (nm)

300

40 60 80 100 120 140 160 180 200 T

PEDOT:PSS thickness (nm)

Figure 2. Refractive index (n) and extinction coefficient (k) spectra: (a) perovskite film; (b) PEDOT:PSST film; (c) doped Spiro-OMeTAD film; (d) doped P3HT film derived from spectroscopic ellipsometry. Calculated reflectance of the solar cells with the structure of glass/FTO/c-TiO2/m-TiO2/CH3NH3PbI3-xClx/HTL/PEDOT:PSST as a function of the thickness of PEDOT:PSST electrode: (e) with doped Spiro-OMeTAD HTL; (f) with doped P3HT HTL.


Nano Letters

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Figure 3. (a) Photographic images of perovskite cells (glass/FTO/c-TiO2/m-TiO2/CH3NH3PbI3xClx/HTL/PEDOT:PSS

T

, the HTL was doped Spiro-OMeTAD or doped P3HT, respectively),

PEDOT:PSST has different thicknesses (40 -160 nm) or different (1-4) layers. (b) Experimental (the incident angle of 8o) and simulated reflectance of part of Spiro-OMeTAD HTL-based devices. (c) Colors of Spiro-OMeTAD-based and P3HT-based devices in the CIE 1931 chromaticity space, respectively.


Illumination from FTO side

15

10

10

-2

-10

5

5

-15

0 0

50

100

)

-2

0 200

150

Times (s)

-20 -25

0.0

0.2

0.4

0.6

0.8

0

-5

15

10

10

5

5

50

100

150

0 200

Times (s)

-15

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Voltage (V) 100

Illumination from PEDOT:PSS T side

20 -2

(d)

20 -2

Illumination from FTO side

Integrated current (mA cm )

100

15

0 0

Voltage (V)

(c)

20

-10

-20

1.0

20

15

60 10 40 48 nm 95 nm 160 nm

20

0 300

400

500 600 700 Wavelength (nm)

5

0 800

80

EQE (%)

80

Integrated current (mA cm )

15

48 nm 95 nm 160 nm

PCE (%)

20

5

-2

-5

20

Current Density (mA cm

0

Illumination from PEDOT:PSST side

(b)

48 nm 95 nm 160 nm

Jmpp (mA cm )

Current Density (mA cm

-2

)

5

PCE (%)

(a)

EQE (%)

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

Nano Letters

Jmpp (mA cm )

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15

60 10 40 48 nm 95 nm 160 nm

20

0 300

400

500 600 700 Wavelength (nm)

5

0 800

Figure 4. Current-voltage (J-V) curves of the colorful perovskite solar cells (glass/FTO/cTiO2/m-TiO2/CH3NH3PbI3-xClx/Spiro-OMeTAD/PEDOT:PSST) where the thickness values of PEDOT:PSST electrodes are 48 nm, 95 nm, and 160 nm, illuminated from glass/FTO side (a) and (b) PEDOT:PSST side, respectively. The inset is stabilized photocurrent at maximum power point (mpp, Vmpp = 0.88V) and PCE of a colored cell with a 95 nm-thick PEDOT:PSST layer. EQE spectra of the colored cell with PEDOT:PSST of different thickness illuminated from glass/FTO side (c) and (d) PEDOT:PSST side.


Nano Letters

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Table 1. Photovoltaic characteristics and CIE 1931 coordinates of the colored cells (SpiroOMeTAD HTL) with different PEDOT:PSST layers averaged over 10 devices for each geometry.

PEDOT:PSST

48 nm

CIE 1931 (x, y)

(0.27, 0.25)

95 nm

(0.25, 0.35)

160 nm

2 × 48 nm

VOC (V)

JSC (mA/cm2)

FF (%)

PCE (%)

FTO

1.08±0.01

18.7±0.3

63±2

12.8±0.3

PEDOT:PST

1.09±0.02

16.7±0.4

65±1

11.6±0.4

FTO

1.11±0.03

19.3±0.3

71±1

15.2±0.5

FTO

1.11±0.04

19.2±0.4

71±2

15.1±0.4

PEDOT:PST

1.11±0.02

16.7±0.3

74±1

13.8±0.4

FTO

1.11±0.02

19.3±0.2

70±3

15.2±0.3

PEDOT:PST

1.12±0.03

16.2±0.4

74±1

13.4±0.4

FTO

1.11±0.02

19.0±0.3

73±2

15.4±0.2

PEDOT:PST

1.10±0.03

14.0±0.5

74±1

11.6±0.3

FTO

1.07±0.01

18.59±0.3

65±2

13.0±0.3

(0.39, 0.29)

75 nm

105 nm

Illumination side

(0.32, 0.39)

(0.41, 0.40)

(0.23, 0.30)


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Nano Letters

Table of Contents Graphic:


Efficient Colorful Perovskite Solar Cells Using a Top Polymer

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