Supporting Information Solvent-Assisted Thermal-Pressure Strategy for Constructing High-Quality CH 3 NH 3 PbI 3-x Cl x Films as High-Performance Perovskite Photodetectors Ning Dong, Xianwei Fu, Gang Lian, *,, Song Lv, Qilong Wang, Deliang Cui, *, and Ching- Ping Wong State Key Lab of Crystal Materials, Shandong University, Jinan 250100, P.R. China Key Laboratory for Special Functional Aggregated Materials of Education Ministry, School of Chemistry & Chemical Engineering, Shandong University, Jinan 250100, P.R. China School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States Corresponding Authors: * E-mail: liangang@sdu.edu.cn * E-mail: cuidl@sdu.edu.cn S-1
I. Experimental Section... S-3 II. Figure S1. (a) XRD patterns of the CA and ST CH 3 NH 3 PbI 3-x Cl x films. (b) Peak intensity ratios of (110) to (310) planes for the CA and ST CH 3 NH 3 PbI 3-x Cl x films.... S-6 III. Figure S2. Top-view SEM image of the CA CH 3 NH 3 PbI 3-x Cl x film.... S-7 IV. Figure S3. (a) X-ray photoelectron spectroscopy (XPS) survey spectrum of the ST film. (b) XPS spectrum of I 3d. (c) XPS spectrum of Cl 2p... S-8 V. Figure S4. Three-dimensional topographic image of the ST CH 3 NH 3 PbI 3-x Cl x film.... S-9 VI. Figure S5. Cross-section SEM image of the CA CH 3 NH 3 PbI 3-x Cl x film.... S-10 VII. Figure S6. Top-view SEM images of the boundary between grains of ST CH 3 NH 3 PbI 3-x Cl x films.... S-11 VIII. Figure S7. I V curves of photodetectors with CA and ST films in dark.... S-12 IX. Figure S8. Detectivity of the CA film photodetector as a function of light intensity at 671 nm laser.... S-13 X. Table S1. Performance comparison of our ST film-based photodetector with other reported perovskite photodetectors.... S-14 XI. References... S-15 S-2
I. Experimental Section Materials and Reagents. The chemical reagents used for preparing CH 3 NH 3 PbI 3-x Cl x films were methylammonium iodide (MAI, AR, Tokyo Chemical Industry Co., Ltd, Tokyo, Japan), PbCl 2 (AR, Aladdin Industrial Corporation, Shanghai, China), dimethylformamide (DMF, AR, Sinopharm Chemical Reagent Co., Ltd, China), and cyclohexane (CYH, AR, Sinopharm Chemical Reagent Co, Ltd, China). All the reagents were used as received without further purification. Fabrication of CH 3 NH 3 PbI 3-x Cl x films by conventional annealing (CA) method. The CH 3 NH 3 PbI 3-x Cl x film was prepared by the spin-coating method as illustrated in Figure 1. According to the previous reported result, 1,2 the molar ratio of MAI and PbCl 2 was set at 3:1 in our experiments. In a typical process, Methylammonium iodide(mai) and lead(ii) chloride (PbCl 2 ) were dissolved in dimethylformamide (DMF) with a molar ratio 3:1 at 65 ºC under stirring, and the solution was continuously stirred for 12 h for preparing the precursor solution. Prior to the preparation of CH 3 NH 3 PbI 3-x Cl x film, the glass substrate was thoroughly cleaned by following the cleaning process of silicon wafers. Afterwards, 100 µl of precursor solutions was spin-coated onto the glass substrate at 2200 rpm for 9 s, followed by another spin-coating process at 3500 rpm for 60 s. Then the CH 3 NH 3 PbI 3-x Cl x films were preheated at 80 ºC for 10 min, and further annealed at 100 ºC for 30 min. The resultant he CH 3 NH 3 PbI 3-x Cl x film was denoted as conventional annealing (CA) film. All these manipulation processes were performed in a glove-box filled with high purity (99.999%) nitrogen gas. Fabrication of CH 3 NH 3 PbI 3-x Cl x films by solvent-assisted thermal-pressure (ST) strategy. The preheated precursor films were firstly placed in a glass desiccator fulfilled with saturation cyclohexane vapor for 1 h in glove-box, thus the CH 3 NH 3 PbI 3-x Cl x vapor was uniformly S-3
adsorbed on the surface of precursor film (Figure 1). The ambient temperature was kept constant at 25~30 C during this process. Afterwards, a silicon wafer was covered on top of the film. After being tightly wrapped with Teflon membrane, the packed film and silicon wafer were transferred into a hot-press autoclave fulfilled with simethicone. During the experimental process, the simethicone serves as the uniform transmission medium for both the heat and pressure. Thirdly, a pressure of 200 MPa was applied on the autoclave, and the temperature was increased to 100 C at a rate of 2 C/min. After kept at 100 C and 200 MPa for 3 h, the autoclave was cooled to room temperature at a rate of 0.014 C/min. Finally, when the pressure was released, the obtained CH 3 NH 3 PbI 3-x Cl x film was denoted as ST film. Measurement and Characterization. X-ray diffraction (XRD) patterns were recorded with a Bruker-AXS Microdiffractometer (D8ADVANCE) using Cu Kα X-ray radiation (λ=1.5406a). The morphologies of the samples were investigated on a field emission scanning electron microscope (Hitachi S-4800) with an accelerating voltage of 7.0 kv. The EDS was performed by an energy dispersive X-ray spectrometer equipped in the SEM machine. UV vis diffuse reflectance spectra were carried out with the wavelength range 800 200 nm on a Shimadzu UV 2550 recording spectrophotometer equipped with an integrating sphere. The XPS was analyzed using a Thermo Fisher Scientific (ESCALAB 250) X-ray photoelectron spectrometer, and C1s (284.6 ev) was used to calibrate the peak positions of the elements. PL spectra were taken using a F-380 fluorescence spectrometer (Tianjin Gangdong Sci. & Tech. Development Co. Ltd. China). Time-resolved PL measurement was collected using a fluorescence lifetime measurement system (C11367-11, Hamamatsu Photonics, Japan). I-V and dynamic response curves of the CH 3 NH 3 PbI 3-x Cl x film photodetector were recorded on a Keithley 4200-SCS semiconductor parameters analyzer at S-4
room temperature in N 2 atmosphere. The time-dependent photoresponse signal was recorded by digital oscilloscope with a Keithley 4200-SCS semiconductor parameters analyzer in N 2 atmosphere. Before the characterization, the sealed sample chamber was under vacuum using a pump. Then residual air in the chamber was completely expelled with high purity N 2 to avoid the influence of H 2 O and O 2. The entire measuring procedure was completed in N 2 atmosphere. S-5
II. Figure S1. (a) XRD patterns of the CA and ST CH 3 NH 3 PbI 3-x Cl x films. (b) Peak intensity ratios of (110) to (310) planes for the CA and ST CH 3 NH 3 PbI 3-x Cl x films. S-6
III. Figure S2. Top-view SEM image of the CA CH 3 NH 3 PbI 3-x Cl x film. S-7
IV.Figure S3. (a) X-ray photoelectron spectroscopy (XPS) survey spectrum of the ST film. (b) XPS spectrum of I 3d. (c) XPS spectrum of Cl 2p. The X-ray photoelectron spectroscopy (XPS) of the ST film was performed to investigate the element composition in the CH 3 NH 3 PbI 3-x Cl x film. Figure S3 shows that the elements of C, N, Pb, I and Cl are easily detected in it. The XPS-determined molar ratio of Cl element in the ST film is 3.45 %. S-8
V. Figure S4. Three-dimensional topographic image of the ST film. S-9
VI. Figure S5. Cross-section SEM image of the CA CH 3 NH 3 PbI 3-x Cl x film. S-10
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VIII. Figure S7. I V curves of photodetectors with CA and ST films in dark. S-12
IX. Figure S8. Detectivity of the CA film photodetector as a function of light intensity at 671 nm laser. S-13
X. Table S1. Performance comparison of our ST film-based photodetector with other reported perovskite photodetectors. Materials Channel (µm) Incidence light Photocurrent On/off Detectivity (Jones) Rise/decay time Ref MAPbI 3 film 1000 532 nm 11 µa (10 V,34 mw/cm 2 ) 1790 2.9 10 12 7.7 ms/ 6 ms 3 MAPbI 3 nanowire 350 650 nm 115 na (2 V,80 µw/cm 2 ) 23 2.5 10 12 0.2 ms/ 0.3 ms 4 MAPbI 3 film 15 780 nm 15.2 µa (8 V,0.2 mw/cm 2 ) 33 _ <0.1 s/ 0.1 s 5 MAPbI 3-x Cl x film 9 380 nm 380 na (2 V,194.2mW/cm 2 ) 2235 _ 0.2 µs/ 0.7 µs 6 MAPbI 3 microwire 1000 630 nm 180 na (10 V,0.1 mw/cm 2 ) 160 2.39 10 12 <10 ms/ 10 ms 7 MAPbI 3-x Cl x film _ 635 nm 180 na (2.1 V,1.4 mw/m 2 ) 16 1.63 10 12 160 ms/ 130 ms 8 MAPbI 3-x Cl x film _ 550 nm 3 10 11 ~30 ms 9 MAPbI 3 microwire 150 650 nm >10 µa (30 V,1 mw/cm 2 ) _ 5.25 10 12 80 µs/ 240 µs 10 MAPbI 3 nanowire 200 650 nm 25 na (10 V,100 µw/cm 2 ) 300 1.02 10 12 0.3 ms/ 0.4 ms 11 MAPbI 3-x Cl x film 400 671 nm 83 µa (10 V,20.6mW/cm 2 ) 2.1 10 4 1.3 10 12 54 µs/ 63 µs This work S-14
XI. References (1) Yang, Y.; You, J.; Hong, Z.; Chen, Q.; Cai, M.; Song, T. Bin; Chen, C. C.; Lu, S.; Liu, Y.; Zhou, H. Low-Temperature Solution-Processed Perovskite Solar Cells with High Efficiency and Flexibility. ACS Nano 2014, 8, 1674 1680. (2) Liang, P. W.; Liao, C. Y.; Chueh, C. C.; Zuo, F.; Williams, S. T.; Xin, X. K.; Lin, J.; Jen, A. K. Y. Additive Enhanced Crystallization of Solution-Processed Perovskite for Highly Efficient Planar-Heterojunction Solar Cells. Advanced Materials 2014, 26, 3748 3754. (3) Tong, S.; Wu, H.; Zhang, C.; Li, S.; Wang, C.; Shen, J.; Xiao, S.; He, J.; Yang, J.; Sun, J.; Gao, Y. Large-Area and High-Performance CH 3 NH 3 PbI 3 perovskite Photodetectors Fabricated via Doctor Blading in Ambient Condition.Organic Electronics: physics, materials, applications 2017, 49, 347 354. (4) Deng, H.; Dong, D.; Qiao, K.; Bu, L.; Li, B.; Yang, D.; Wang, H.-E.; Cheng, Y.; Zhao, Z.; Tang, J.; Song, H. Growth, Patterning and Alignment of Organolead Iodide Perovskite Nanowires for Optoelectronic Devices. Nanoscale 2015, 7 (9), 4163 4170. (5) Hu, X.; Zhang, X.; Liang, L.; Bao, J.; Li, S.; Yang, W.; Xie, Y. High-Performance Flexible Broadband Photodetector Based on Organolead Halide Perovskite. Advanced Functional Materials 2014, 24 (46), 7373 7380. (6) Guo, Y.; Liu, C.; Tanaka, H.; Nakamura, E. Air-Stable and Solution-Processable Perovskite Photodetectors for Solar-Blind UV and Visible Light. Journal of Physical Chemistry Letters 2015, 6 (3), 535 539. S-15
(7) Liu, Y.; Li, F.; Perumal Veeramalai, C.; Chen, W.; Guo, T.; Wu, C.; Kim, T. W. Inkjet- Printed Photodetector Arrays Based on Hybrid Perovskite CH 3 NH 3 PbI 3 Microwires. ACS Applied Materials & Interfaces 2017, 9 (13), 11662 11668. (8) Bhatt, V.; Kumar, M.; Yadav, P.; Kumar, M.; Yun, J. H. Low Cost and Solution Processible Sandwiched CH 3 NH 3 PbI 3-x Cl x based Photodetector. Materials Research Bulletin 2018, 99 (November 2016), 79 85. (9) Dou, L.; Yang, Y. M.; You, J.; Hong, Z.; Chang, W.-H.; Li, G.; Yang, Y. Solution- Processed Hybrid Perovskite Photodetectors with High Detectivity. Nature communications 2014, 5, 5404. (10) Deng, W.; Zhang, X.; Huang, L.; Xu, X.; Wang, L.; Wang, J.; Shang, Q.; Lee, S. T.; Jie, J. Aligned Single-Crystalline Perovskite Microwire Arrays for High-Performance Flexible Image Sensors with Long-Term Stability. Advanced Materials 2016, 28 (11), 2201 2208. (11) Deng, H.; Yang, X.; Dong, D.; Li, B.; Yang, D.; Yuan, S.; Qiao, K.; Cheng, Y. B.; Tang, J.; Song, H. Flexible and Semitransparent Organolead Triiodide Perovskite Network Photodetector Arrays with High Stability. Nano Letters 2015, 15 (12), 7963 7969. S-16