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Pinhole-Free Hybrid Perovskite Film with Arbitrarily-Shaped Micro-Patterns for Functional Optoelectronic Devices Jiang Wu, Junyan Chen, Yifei Zhang, Zhaojian Xu, Lichen Zhao, Tanghao Liu, Deying Luo, Wenqiang Yang, Ke Chen, Qin Hu, Fengjun Ye, Pan Wu, Rui Zhu, and Qihuang Gong Nano Lett., Just Accepted Manuscript • Publication Date (Web): 26 Apr 2017 Downloaded from http://pubs.acs.org on April 26, 2017

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Pinhole-Free Hybrid Perovskite Film with Arbitrarily-Shaped Micro-Patterns for Functional Optoelectronic Devices Jiang Wu,† Junyan Chen,† Yifei Zhang,† Zhaojian Xu,† Lichen Zhao,† Tanghao Liu,† Deying Luo,† Wenqiang Yang,† Ke Chen,† Qin Hu,† Fengjun Ye,† Pan Wu,† Rui Zhu*,†,‡,§, Qihuang Gong†,‡,§ †

State Key Laboratory for Artiﬁcial Microstructure and Mesoscopic Physics, Department of

Physics, Peking University, Beijing, 100871, China ‡

Collaborative Innovation Center of Quantum Matter, Beijing, 100871, China

§

Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi,

030006, China

ABSTRACT: In many optoelectronic applications, patterning is required for functional and/or aesthetic purposes. However, established photolithographic technique can’t be applied directly to the hybrid perovskites, which are considered as promising candidates for optoelectronic applications. In this work, a wettability-assisted photolithography (WAP) process, which employs photolithography and one-step solution process to deposit hybrid perovskite, was

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developed for fabricating patterned hybrid perovskite films. Uniform pinhole-free hybrid perovskite films with sharp-edged micro-patterns of any shapes can be constructed through the WAP process. Semitransparent solar cells with an adjustable active layer average visible transmittance (AL AVT) of a wide range from 20.0% to 100% and regular solar cells based on patterned CH3NH3PbI3 perovskite films were fabricated to demonstrate that the WAP process was compatible with the manufacturing process of optoelectronic devices. With the widelyequipped photolithographic facilities in the modern semiconductor industry, we believe the WAP process have a great potential in the industrial production of functionally- or aestheticallypatterned hybrid perovskite devices.

KEYWORDS: patterning, photolithography, perovskite solar cells, semi-transparent solar cells

Owing to the advantages of low cost,1 easy processability,2 long carrier diffusion length,3-5 high carrier mobility,6 and low trap density,7, 8 the organic-inorganic hybrid perovskite material has attracted tremendous attention all over the world as a new and promising candidate for diverse optoelectronic applications, such as solar cells,9-13 light-emitting diodes (LEDs),14 photodetectors,15 and lasers.16 In many optoelectronic applications, patterning is required for functional and/or aesthetic purposes. For example, patterning meandering structures for integrated circuits;17 patterning pixel matrices for displaying;18 patterning mesa structures for waveguiding;19 and patterning for aesthetic purpose. Thus there is an increasing need to develop methods for patterning the organic-inorganic hybrid perovskite material. As we know, conventional photolithography followed by dry or wet etching processes, easily accessible in the


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current semiconductor industry, is mostly common and powerful for micropatterning.20 However, established photolithographic technique can’t be applied directly to the hybrid perovskite due to its solubility in various solvents and the sensitivity of the organic moiety in perovskites.21-24 To fabricate patterned hybrid perovskite microplates or microscale crystals, a few methods were studied recently. In the year of 2015, Duan and co-workers25 reported a strategy that produced PbI2 seed arrays in photolithography pre-patterned regions and then grew the perovskite arrays by vapor-phase conversion. By a similar way in 2016, Liu and co-workers26 produced perovskite arrays on chemical vapor deposition (CVD) synthesized and photolithography pre-patterned boron-nitride. In the same year, Jiang and co-workers27 developed another method that splitted perovskite precursor liquid and located liquid domains by wettability-mediated micro-pillar-structured silicon template. Also in 2016, Kaehr and coworkers28 demonstrated a laser direct-write patterning procedure for perovskites by heating the perovskite precursor in micro scale. Moreover, as the thin-film structure was employed by many optoelectronic devices, a few methods were studied to fabricate patterned hybrid perovskite films. In the year of 2015, Snaith and co-workers29 presented a scalable technique for fabricating micro-structured metal oxide scaffolds that could form the perovskite thin films into a honeycomb structure. Via similar ways in 2016, researchers successfully fabricated perovskite grids with better uniformity.30, 31 In the year of 2015, Ooi and co-workers32 employed focused-ion beam (FIB) etching to pattern perovskite film. Through an idea similar to etching, Hu and co-workers33 employed nanoimprint lithography to fabricate perovskite with structures of grid and nanograting in 2016. Park and co-


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workers20 also presented a nondestructive micropatterning process and a solvent-assisted gel printing process through nanoimprint technology in 2016. In this work, a wettability-assisted photolithography (WAP) patterning process was demonstrated, which enables the fabrication of arbitrarily-shaped pinhole-free hybrid perovskite thin-films. The WAP process produces a photolithography pre-patterned auxiliary layer which is lyophobic to the perovskite precursor solution, then deposits patterned hybrid perovskite films through one-step solution process. In comparison to other patterning methods for hybrid perovskites to date, the WAP process realized uniform pinhole-free hybrid perovskite thin-films of arbitrarily-shaped complex patterns with clear edges. The WAP process employed photolithography and one-step solution process to deposit hybrid perovskite, which made it easy to operate and spread. Moreover, the WAP process employed no complicated additional processes such as etching, pressing, lifting-off, transferring on the hybrid perovskite films to realize a fast nondestructive patterning method which suits for fabrication processes of most optoelectronic applications. Uniform CH3NH3PbI3 perovskite with simple or advanced patterns were demonstrated through the WAP process. To certify the uniformity and compatibility of the WAP process, patterned CH3NH3PbI3 perovskite solar cells based on a regular structure with a perovskite coverage ratio (the ratio of the patterned perovskite’s area divided by the solar cell’s active area) of 44% were fabricated. Furthermore, to demonstrate the functional usage and compatibility of the WAP process, semitransparent solar cells of an inverted structure based on patterned perovskite films with an adjustable active layer average visible transmittance (AL AVT) of a wide range from 20.0% to 100% were fabricated.


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Figure 1. Schematics of the WAP process for patterned CH3NH3PbI3 perovskite film. (a) Fabrication of the photoresist template on Poly-TPD through photolithography. (b) Duplicating the design of the photoresist template by CB spin-drop-casting. (c) Removing the photoresist template by DMF spin-drop-casting. (d) Deposition of CH3NH3PbI3 perovskite by one-step spincoating on the patterned hydrophobic surface of Poly-TPD. (e) Removing the Poly-TPD by CB spin-drop-casting.


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The fabrication of patterned CH3NH3PbI3 perovskite films using the WAP process was demonstrated in Figure 1. Initially, a solution of poly(4-butylphenyl-diphenyl-amine) (polyTPD) in chlorobenzene (CB) was coated on the top of a pre-cleaned glass substrate. Then standard photolithographic method34 was used to generate a photoresist layer with microstructured patterns that acted as a template for the WAP process. The films were then spin-dropcasted with CB to duplicate the patterning of the photoresist template on the poly-TPD layer. Subsequently, the photoresist template was removed by N,N-dimethylformamide (DMF) spindrop-casting to expose the hydrophobic surface of the patterned poly-TPD film. After that, patterned CH3NH3PbI3 perovskite was constructed in hydrophilic regions by one-step spincoating with a precursor solution of lead acetate (Pb(Ac)2) accompanied by methylammonium iodide (MAI) in DMF.35 Finally, the poly-TPD layer was removed by CB spin-drop-casting. Pinhole free hybrid perovskite films with any micro-patterns can be realized through the WAP process employing the appropriate photolithographic template.


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Figure 2. The photograph and SEM images for the patterned CH3NH3PbI3 perovskite films. (a-c) SEM images for the CH3NH3PbI3 arrays of rounded units. SEM images of (d) CH3NH3PbI3 and (e) CH3NH3PbI3 hexagonal units arranged in “PKU” patterns. (f) SEM image of CH3NH3PbI3 film with open holes arranged in “PKU” patterns. SEM images of (g) a 10-µm-wide meander line and (h) 10-µm-wide, 10-µm-spaced microelectrodes of CH3NH3PbI3 film. (i) Photograph and (j) SEM image of CH3NH3PbI3 with advanced tower-shaped patterns. Figure 2 shows the photograph and scanning electron microscope (SEM) images of the patterned CH3NH3PbI3 perovskite films. Figure 2a~2c are the SEM images of the CH3NH3PbI3


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perovskite arrays of rounded units at different magnifications. Figure 2c proves that the WAP process can form uniform pinhole-free CH3NH3PbI3 films suitable for optoelectronic devices. Not only periodic arrays, hybrid perovskite films with any micro-patterns can be realized through the WAP process. To demonstrate this, Figure 2d and 2e show SEM images of CH3NH3PbI3 and CH3NH3PbI3 hexagonal units arranged in “PKU” patterns, respectively; and Figure 2f shows a CH3NH3PbI3 film with open holes arranged in “PKU” patterns. To demonstrate the usages of the WAP process for functional purpose, a 10-µm-wide meander line of CH3NH3PbI3 is shown in Figure 2g; and 10-µm-wide, 10-µm-spaced microelectrodes of CH3NH3PbI3 are shown in Figure 2h with clear edges. In addition, to demonstrate the usages of the WAP process for aesthetic purpose, Figure 2i and 2j show the photograph and SEM image of CH3NH3PbI3 with complex tower-shaped patterns, respectively.


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Figure 3. (a) Schematic of the device architecture based on patterned perovskite. (b) Current density-voltage characteristics of the devices based on different active layers under simulated AM 1.5G 1 Sun illumination. Inset: summary of the device performance. (c) Optical microscopic picture of the patterned perovskite films. (d) Height profile characterization for the devices based on patterned perovskite during the fabrication process. As the patterned hybrid perovskite films got uniform pinhole-free surfaces and sharp edges, we expect the patterned hybrid perovskite film to have a good performance in functional optoelectronic devices. To evaluate this, patterned perovskite solar cells were fabricated with a


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device configuration: glass/FTO/TiO2/patterned Al2O3±x:patterned CH3NH3PbI3(250 nm)/SpiroOMeTAD/Au, as illustrated in Figure 3a. Devices based on architecture of glass/FTO/TiO2/CH3NH3PbI3(250 nm)/Spiro-OMeTAD/Au were also fabricated for comparison. As shown in Figure S1g, the insulating Al2O3±x layer was patterned to block shunting paths in the partially covered perovskite film without obstructing the charge transport through the perovskite. All patterned perovskite devices without the Al2O3±x blocking layer were shorted out. Figure 3b shows the current density versus voltage curves. The inset in Figure 3b summarizes the device performance. For the control devices using continuous perovskite film as the active layer, a power conversion efficiency (PCE) of 16.0% was achieved with a short circuit current (Jsc) of 22.8 mA·cm-2, a fill factor (FF) of 0.68, and an open circuit voltage (Voc) of 1.03 V. After patterning the perovskite film into arrays of circle units with a diameter of 45.1 µm and a center distance of 60 µm (see Figure S2), only 44% of the compact TiO2 surface were covered with perovskite. Thus, as illustrated by “Perovskite with Jsc scaled down to 44%” in Figure 3b, the current density of devices based on the patterned perovskite should be 44% of that based on the perovskite w/o patterning at the same bias. The experimental and calculated J-V curves of the devices based on patterned perovskite are in agreement, proving that the perovskite films patterned by WAP process are suitable for and have a great potential in optoelectronic device manufacture. To investigate the periodical waviness and roughness of the devices based on patterned perovskite, Figure 3c and 3d show optical microscopic image of the patterned perovskite film and the corresponding surface height profiles measured over 0.6 mm. As shown in Figure 3d, the height of the device fabricated through the WAP process had an obvious periodicity and the repeat units had a good conformity. The 225 nm height difference between the highest and


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lowest region caused by the patterned perovskite units decreased to 140 nm after the coating of the 2,2’,7,7’-Tetrakis[ N,N -di(4-methoxyphenyl)amino]-9,9’,-spirobifluorene (Spiro-OMeTAD) layer, and further reduced to 125 nm after the evaporation of 100-nm-thick Au electrode. From the height data before and after Au evaporation, it can be inferred that the Au electrodes turned out to be continuous, providing a qualified conductivity in spite of the wavy surface. The experimental devices based on patterned perovskite films got a PCE of 6.55%, a Jsc of 9.83 mA·cm-2, a FF of 0.66 and a Voc of 1.01V. This slight performance decline of the experimental device compared with the calculated one was probably caused by the uneven holetransporting layer on the periodical patterned perovskite surface, especially in the edge area of the patterns. As the performance decline was very slight, the WAP process turned out to be a compatible and powerful method for perovskite patterning in optoelectronic devices.

Figure 4. (a) Schematic of the semitransparent device based on patterned perovskite. (b) Crosssectional schematic of the device architecture. (c) Cross-sectional SEM image of the perovskite


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unit’s boundary. (d) Optical transmittance spectra of the continuous perovskite film and corresponding patterned perovskite film with a perovskite coverage ratio of 44%. Inset: photograph of semitransparent perovskite solar cells based on a patterned perovskite film with a perovskite coverage ratio of 44% (above) and the corresponding continuous perovskite film (down); the yellow brackets indicate the top Ag NW-based electrode. (e) Current density-voltage characteristics of the semitransparent devices based on different active layers under simulated AM 1.5G 1 Sun illumination (illuminated from FTO side). After patterning the perovskite film into arrays, there was a substantial increase in visible transparence which made the patterned perovskite film suitable for semitransparent optoelectronic devices. To further evaluate the performance of the patterned hybrid perovskite films in patterned optoelectronic devices, semitransparent patterned perovskite solar cells were fabricated with an inverted device structure: glass/FTO/Cu:NiOy/patterned Al2O3±x:patterned CH3NH3PbI3(410 nm)/PC61BM/ZnO/silver nanowires (Ag NWs)/ZnO, as illustrated in Figure 4a. (See Figure S3 for detailed fabrication process.) Devices based on architecture of glass/FTO/Cu:NiOy/CH3NH3PbI3(410 nm)/PC61BM/ZnO/Ag NWs/ZnO (continuous perovskite active layer) and glass/FTO/Cu:NiOy/patterned CH3NH3PbI3(410 nm)/PC61BM/ZnO/Ag NWs/ZnO (patterned perovskite without blocking layer) were also fabricated for comparison. The Cu-doped nickel oxide (Cu:NiOy) hole-transporting layer36 and ZnO nanoparticle electrontransporting layer37 was reported elsewhere. The perovskite coverage ratio of the devices based on patterned perovskite was 44%. Figure 4b and 4c show the cross-sectional schematic of the device architecture based on patterned perovskite and the corresponding cross-sectional SEM image of the perovskite unit’s boundary. Figure 4d compares the transmission spectra of the continuous perovskite film and the corresponding patterned perovskite film. For the 300-nm-


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thick continuous perovskite film, an average visible transmission (AVT) of 20.0% was observed. After patterning the perovskite film into arrays (as shown in Figure S2), a significant increased AVT of 62.4% was obtained. Since only 44% of the substrate surface were covered with perovskite, the transmittance of patterned perovskite film could be calculated as:

T patterned (λ ) = 1 − 44 % × [1 − Tcontinuous (λ )]

(1)

where Tcontinuous (λ) is the optical transmittance of the corresponding continuous perovskite film. The experimental and the calculated spectra are in agreement (shown in Figure 4d), proving that the WAP process can construct patterns precisely. This was also reflected in the agreement of the experimental and calculated J-V curves in Figure 3b. Through the WAP process, semitransparent perovskite solar cells with an active layer average visible transmittance adjustable from 20.0% (perovskite coverage ratio of 100%) to 100% (perovskite coverage ratio of 0%) can be manufactured. The inset of Figure 4d shows a photograph of the semitransparent perovskite solar cell based on the patterned perovskite film with perovskite coverage ratio of 44% (above) and that based on corresponding continuous perovskite film (down). The difference in the transmission between these two devices is evident. Figure 4e shows the current density versus voltage curves. For the control devices using continuous perovskite film as the active layer, a PCE of 9.08% was achieved with a Jsc of 15.2 mA·cm-2, a FF of 0.58, and a Voc of 1.03 V. The devices based on patterned perovskite films without the patterned Al2O3±x blocking layer got a poor PCE of 0.94%, a Jsc of 4.26 mA·cm-2, a FF of 0.45 and a Voc of 0.49 V. The devices based on patterned perovskite films with the blocking layer got an improved PCE of 2.36%, a Jsc of 5.44 mA·cm-2, a FF of 0.55 and a Voc of 0.79 V, which were still lower than the calculated performances (see Figure 4e, “Perovskite with Jsc scaled down to 44%”). The unequable diffusion lengths caused by the uneven electron-


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transporting layer (i.e. the spin-coated ZnO/Ag NWs/ZnO composite electrode) on the periodical patterned perovskite surface, especially in the edge area of the patterns, might lead to this performance decline of the experimental device compared with the calculated one. We expect a better performance if more appropriate electrodes were employed. In conclusion, a wettability-assisted photolithography process was developed for fabricating patterned hybrid perovskite films and optoelectronic devices based on them. The WAP process solved the problem that established photolithographic techniques, which was widely equipped and used in the modern semiconductor industry, can’t be applied directly to the hybrid perovskites. Uniform pinhole-free hybrid perovskite films with any sharp-edged micro-patterns can be constructed through the WAP process. Regular and semitransparent perovskite solar cells of regular and inverted structure based on patterned CH3NH3PbI3 perovskite films were fabricated to demonstrate that the WAP process was compatible with the manufacturing process of optoelectronic devices. With the established widely-equipped photolithographic facilities in the modern semiconductor industry, we believe the WAP process have a great potential in the industrial production of functionally- or aesthetically-patterned hybrid perovskite devices as soon as the study of hybrid perovskite is ready. Experimental Section. Materials: All liquid reagents were purchased from Acros and used as received. The photoresist was purchased from Ruihong Tech. Poly-TPD was purchased from Xi’an Polymer Light Tech. MAI were synthesized with MA and hydroiodic acid through the method reported by the previous literature.37 Spiro-OMeTAD was purchased from SunaTech. [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) was purchased from Planck BioTech Inc. (Xi'an, China). ZnO nanoparticles were prepared according to literature procedures.38 The Ag NW ink was purchased from Kechuang Advanced Materials Company. Pb(Ac)2, AlCl3,


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Zn(Ac)2·2H2O, Ni(Ac)2·4H2O, Cu(Ac)2·H2O, KOH, NaOH, hydroiodic acid and acetic acid were purchased from Sinopharm Group Company. Fabrication of regular solar cells based on patterned hybrid perovskite films: See Figure S1 for detailed fabrication process. The FTO substrates were cleaned with a solution of detergent diluted in deionized water and then rinsed with deionized water, acetone and isopropanol. The compact TiO2 electron-transporting layer was fabricated according to a reported procedure.9 The Al2O3±x blocking layer was fabricated according to a reported procedure.39 Poly-TPD was dissolved in CB at a concentration of 20 mg/mL and spin-coated at 3000 rpm. Photolithography was used to produce a 1.7 µm thick photoresist layer with micro-structure patterns. The sample was spin-drop-casted by CB to duplicate the patterning of the photoresist template on the polyTPD layer. Then the sample was dipped into NaOH aqueous solution at a concentration of 3.33 mg/mL for 20 s to duplicate the patterning of the photoresist template on the Al2O3±x layer. Then the sample was spin-drop-casted by DMF to remove the photoresist template and transferred into the glove box filled with N2. To create the perovskite precursor solution, MAI and Pb(Ac)2 were dissolved in anhydrous DMF at a 3:1 molar ratio with a final concentration of 46 wt%. The precursor solution was spin-coated at 4000 rpm for 20 s, and then the samples were directly placed onto a hot plate at 80 °C for 5 min. Then the sample was spin-drop-casted by CB to remove the poly-TPD layer. Subsequently, the Spiro-OMeTAD-based hole-transporting layer (80 mg of Spiro-OMeTAD, 17.5 µL of lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) solution (520 mg of Li-TFSI in 1 mL of acetonitrile) and 28.5 µL of 4-tert-butylpyridine all dissolved in 1 mL of chlorobenzene) was deposited by spin-coating at 2000 rpm for 30 s. Finally, the device was completed by depositing a gold electrode (100 nm) through thermal evaporation.


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Fabrication of semitransparent solar cells based on patterned hybrid perovskite films: See Figure S3 for detailed fabrication process. The FTO substrates were cleaned with a solution of detergent diluted in deionized water and then rinsed with deionized water, acetone and isopropanol. The Cu:NiOy hole-transporting layer was fabricated according to a reported procedure.36 The patterned Al2O3±x and patterned perovskite layer was prepared following the same process as the regular solar cells. Then the PC61BM-based electron-transporting layer was deposited by 15 mg/mL PC61BM dissolve in CB for spin-coating at 1000 rpm. Then a 100-nmthick ZnO nanoparticle layer was spin drop-casted on the top of the PC61BM at 7000 rpm. The Ag NW ink was spin drop-casted on the top of the ZnO nanoparticle layer at 3000 rpm. Finally, another 100-nm-thick ZnO nanoparticle layer was spin drop-casted to complete the device. Characterization of organic solar cells: The current-voltage curves were measured in a glove box using a Keithley 2400 source-measure unit. The cells (active area: 8.63 mm2) were illuminated by a 150 W class AAA solar simulator (XES-40S1, SAN-EI) equipped with an AM 1.5G filter at a calibrated intensity of 100 mW·cm-2. Light intensity was determined by a standard monocrystal silicon photodiode calibrated by the Newport TAC-PV lab. Other characterizations: The SEM images were collected by a FEI Nova_NanoSEM 430 fieldemission SEM. The optical transmittance spectra was collected by a UV-visible spectrophotometer (Agilent 8453). The height of the surface was collected by a Dektak stylus profiler.

ASSOCIATED CONTENT


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Supporting Information. Supporting Information Available: Information about the Al2O3±x blocking layer and detailed device fabrication process

AUTHOR INFORMATION Corresponding Author *E-mail: [email protected] Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT This work was financially supported by the 973 Program of China (2015CB932203), the National Natural Science Foundation of China (61377025 and 91433203), and the Young 1000 Talents Global Recruitment Program of China. The authors thank Prof. Zhijian Chen for improving the manuscript, Dr. Rui Zhu (Electron Microscopy Laboratory of Peking University) for the SEM and EDS testing, and Prof. Xinqiang Wang for the calibration of solar simulator. REFERENCES (1) Snaith, H. J. J. Phys. Chem. Lett. 2013, 4, 3623-3630. (2) Liu, T.; Chen, K.; Hu, Q.; Zhu, R.; Gong, Q. Adv. Energy Mater. 2016, 6, 1600457. (3) Xing, G.; Mathews, N.; Sun, S.; Lim, S. S.; Lam, Y. M.; Grätzel, M.; Mhaisalkar, S.; Sum, T. C. Science 2013, 342, 344-347.


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Table of Contents:

Pinhole-Free Hybrid Perovskite Film with Arbitrarily-Shaped Micro-Patterns for Functional Optoelectronic Devices

A wettability-assisted photolithography (WAP) process, which employs photolithography and one-step solution process to deposit hybrid perovskite, is developed for fabricating patterned hybrid perovskite films. Regular and semitransparent perovskite solar cells based on patterned CH3NH3PbI3 films are fabricated to demonstrate that the WAP process is compatible with the manufacturing process of optoelectronic devices.

KEYWORDS: patterning, photolithography, perovskite solar cells, semi-transparent solar cells

Jiang Wu, Junyan Chen, Yifei Zhang, Zhaojian Xu, Lichen Zhao, Tanghao Liu, Deying Luo, Wenqiang Yang, Ke Chen, Qin Hu, Fengjun Ye, Pan Wu, Rui Zhu*, Qihuang Gong


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A wettability-assisted photolithography (WAP) process, which employs photolithography and one-step solution process to deposit hybrid perovskite, is developed for fabricating patterned hybrid perovskite films. Regular and semitransparent perovskite solar cells based on patterned CH3NH3PbI3 films are fabricated to demonstrate that the WAP process is compatible with the manufacturing process of optoelectronic devices. 53x34mm (300 x 300 DPI)


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Figure 1. Schematics of the WAP process for patterned CH3NH3PbI3 perovskite film. (a) Fabrication of the photoresist template on Poly-TPD through photolithography. (b) Duplicating the design of the photoresist template by CB spin-drop-casting. (c) Removing the photoresist template by DMF spin-drop-casting. (d) Deposition of CH3NH3PbI3 perovskite by one-step spin-coating on the patterned hydrophobic surface of Poly-TPD. (e) Removing the Poly-TPD by CB spin-drop-casting. 84x147mm (300 x 300 DPI)


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Figure 2. The photograph and SEM images for the patterned CH3NH3PbI3 perovskite films. (a-c) SEM images for the CH3NH3PbI3 arrays of rounded units. SEM images of (d) CH3NH3PbI3 and (e) CH3NH3PbI3 hexagonal units arranged in “PKU” patterns. (f) SEM image of CH3NH3PbI3 film with open holes arranged in “PKU” patterns. SEM images of (g) a 10-µm-wide meander line and (h) 10-µm-wide, 10-µm-spaced microelectrodes of CH3NH3PbI3 film. (i) Photograph and (j) SEM image of CH3NH3PbI3 with advanced tower-shaped patterns. 177x149mm (300 x 300 DPI)


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Figure 3. (a) Schematic of the device architecture based on patterned perovskite. (b) Current densityvoltage characteristics of the devices based on different active layers under simulated AM 1.5G 1 Sun illumination. Inset: summary of the device performance. (c) Optical microscopic picture of the patterned perovskite films. (d) Height profile characterization for the devices based on patterned perovskite during the fabrication process. 177x147mm (300 x 300 DPI)


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Figure 4. (a) Schematic of the semitransparent device based on patterned perovskite. (b) Cross-sectional schematic of the device architecture. (c) Cross-sectional SEM image of the perovskite unit’s boundary. (d) Optical transmittance spectra of the continuous perovskite film and corresponding patterned perovskite film with a perovskite coverage ratio of 44%. Inset: photograph of semitransparent perovskite solar cells based on a patterned perovskite film with a perovskite coverage ratio of 44% (above) and the corresponding continuous perovskite film (down); the yellow brackets indicate the top Ag NW-based electrode. (e) Current density-voltage characteristics of the semitransparent devices based on different active layers under simulated AM 1.5G 1 Sun illumination (illuminated from FTO side). 177x92mm (300 x 300 DPI)


Pinhole-Free Hybrid Perovskite Film with Arbitrarily ... - ACS Publications

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