Supporting Information for

Transcription

1 Supporting Information for General Space-Confined On-substrate Fabrication of Thickness- Adjustable Hybrid Perovskite Single-Crystalline Thin Films Yao Xuan Chen,,, Qian Qing Ge,,, Yang Shi,, Jie, Liu,, Ding Jiang Xue,, Jing Yuan Ma,, Jie Ding,, Hui Juan Yan,, Jin Song Hu,,, * Li Jun Wan,, * Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Science, 2 North 1 st Street, Zhongguancun, Beijing, , China. University of Chinese Academy of Science, Beijing , China These authors contributed equally. This file includes experimental section, supplementary figures S1-S10. S1

2 EXPERIMENTAL SECTION Chemicals and reagents. Lead bromide ( 98%), lead iodide (99%), DMF (anhydrous, 99.8%) and DMSO (anhydrous, 99.9%) were purchased from Sigma Aldrich. Lead chloride (99.999%) was from Alfa Aesar. GBL (> 99.9% (GC)) was purchased from Aladdin. Methylammonium bromide (MABr), methylammonium chloride (MACl) and methylammonium iodide (MAI) were obtained from Borun (Ningbo, China). All chemicals were used as received without any further purification. Preparation of substrates. The cm <100> monocrystalline silicon wafer, coverslip, FTO/glass and ITO/glass were cleaned with water, ethanol and acetone in an ultrasonic bath for 15 min, respectively. The cm flexible PET substrate in mm thickness was peeled off the protective film for direct use. All the substrates were treated in a UV-Ozone cleaner at 200 W for 15 min prior to use. Fabrication of perovskite SCTFs. In a typical procedure, two substrates were clamped together by two mm glass slides via a clip. 5 ml of 0.7 M, 2.0 M, and 1.23 M precursor solution of PbBr2/MABr, PbCl2/MACl and PbI2/MAI with a molar ratio of 1 : 1 were prepared in DMF, DMSO and GBL, respectively, then filtered using PTFE filter with 0.2 m pore size. The bromide and chloride solutions were prepared at room temperature and the iodide solution was heated up to 60 o C. The clipped substrates were then vertically dipped into a 50 ml beaker with each precursor solution. The beaker was kept on a hot plate at 90 o C for bromide, and 100 o C for chloride and iodide. After 24 ~ 36 hours for bromide and 48 ~ 60 hours for chloride and iodide, the substrates with perovskite SCTFs were moved to vacuum oven for further solvent removal. Measurement and characterization. Optical images were taken using a Nikon ECLIPSE LV150N microscopy. Scanning electron microscopy (SEM) images were obtained on Hitachi S-4800 and SU-8020 microscopes. For SEM measurements, the samples on conductive substrates were directly measured after the separation of the two substrates. The samples on dielectric substrates were sputtered a very thin layer of Au film before SEM measurement. Atomic force microscopy (AFM) data were collected S2

3 on a Bruker Dimension Icon microscope. For AFM measurement, the samples grown on Si substrates were directly measured after the separation of the two substrates without any additional treatment. The standard X-ray diffraction (XRD) experiments were performed at a scan rate of 5 / min on a Rigaku D/max-2500 diffractometer using Cu K radiation. The cm substrates with perovskite films were separated and directly used to collect the XRD signals. The perovskite SCTFs fabricated on clean quartz substrates were used for UV-Vis and PL measurements. The UV-Vis absorption spectra of the perovskite SCTFs were collected on a UV-Vis spectrophotometer (UH4150, HITACHI). The Tauc plots were deduced from steady-state absorption spectra using αhν, where α was absorption coefficient; E was optical bandgap, and m was 1/2 in view of directbandgap MAPbX3. The optical bandgaps of MAPbX3 SCTFs were estimated by extrapolating the linear region of the absorption edge to the energy-axis intercept. The steady-state PL spectrum was measured on a confocal laser scanning microscope (Olympus FV1000-IX81, Japan) with a 405 nm laser. For SCLC measurement, MAPbBr3 SCTF in around 1 m thickness on SiO2(300 nm)/si substrate was patterned with 80 nm thick Au electrodes. Dark I-V curves were measured on a Micromanipulator probe station using a Keithley 4200 semiconductor measurement system. The trap-filled limit voltage (VTFL) was obtained from I-V curve. The trap density ntrap of MAPbBr3 SCTF was calculated by the equation: 2, where e, L,, and ε were electronic charge, channel width, relative dielectric constant of MAPbBr3, and vacuum permittivity, respectively. In the Child s regime (orange line) of dark I-V curve, the dark current showed a quadratic voltage dependence and could be well fitted by the Mott-Gurney law: 9 8, where V was the applied voltage. The carrier mobility (, where and were electron and hole mobility, respectively, given that MAPbBr3 was an intrinsic semiconductor) was determined by the Mott-Gurney law. Impedance spectroscopy (IS) was performed on Autolab PGSTAT 302N (Utrecht, The Netherlands) with a solar simulator (450W, Model 91150, Newport) with an AM S3

4 1.5 spectrum distribution. IS spectrum was recorded under 1 sun illumination at open circuit potential with a frequency range from 1 MHz to 100 Hz. Synchrotron X-ray diffraction. Synchrotron X-ray diffraction results were obtained in the 15U1 beamline at the Shanghai Synchrotron Radiation Facility (SSRF). Diffraction images were collected using MAR-165 charge-coupled device (CCD) detector. The tilting and rotation of the detector relative to the incident X-ray beam were calibrated using cerium dioxide (CeO2) powder as the X-ray diffraction standard. The sample-to-detector distance of approximately 180 mm was calculated from the powder CeO2 diffraction pattern at ambient conditions. The wavelength of the monochromatic X-ray beam was Å, calibrated by scanning through the Mo metal K-absorption edge. For the measurement on MAPbBr3 SCTF/PET, the beam was focused down to 4 4 μm 2 area. For the measurement on MAPbBr3 SCTF/glass substrate, the beam was focused down to μm 2 area. The signals were collected with the exposure time of 60 s. The collected diffraction patterns were integrated to generate the conventional one-dimensional diffraction profiles using the Fit2D program (Hammersley et. al.), which was further transformed into the standard XRD pattern for better comparison using Bragg s law: sin sin Where is incident angle and is wavelength of X-ray source. S4

5 Figure S1. a) SEM image of MAPbBr3 SCTF on silicon substrate. Optical microscopy images of MAPbBr3 SCTFs on b) glass substrate and c) FTO/glass substrate. Optical microscopy images of d) MAPbBr3, e) MAPbCl3, and f) MAPbI3 perovskite SCTFs on PET substrates. S5

6 Figure S2. SEM image of MAPbBr3 SCTF grown on ITO/glass and the corresponding EDS mapping images. Figure S3. High-magnification straight-on SEM images of a,d) MAPbBr3, b,e) MAPbI3, and c,f) MAPbCl3 SCTFs. The smooth top surfaces without grain structures or boundaries were observed on the entire films. S6

7 Figure S4. SEM images and the corresponding EDS mapping images of a) MAPbBr3, b) MAPbCl3, and c) MAPbI3. Figure S5. a) SEM image and b) optical microscopy image of MAPbI3 SCTFs. Different from cubic MAPbCl3 and MAPbBr3 SCTFs which commonly have welldefined edges with right angles, the tetragonal MAPbI3 films usually show the edges with oblique angles. S7

8 Figure S6. a) Synchrotron X-ray diffraction image of MAPbBr3 film on PET substrate collected during the rotation of the incident x-ray beam by ±5. b) Synchrotron x-ray diffraction pattern of blank PET substrate. Figure S7. a) (i) XRD pattern of MAPbBr3 powder ground from a single crystal, recorded using Cu Kα radiation; (ii) XRD pattern integrated from Figure S7b, which was calibrated to Cu Kα. b) Synchrotron X-ray diffraction image of MAPbBr3 SCTFs on glass substrate collected with the incident X-ray beam perpendicular to the sample. S8

9 Figure S8. XRD patterns of the as-grown MAPbBr3 SCTF and that after 5 month store in ambient condition. The MAPbBr3 SCTF was grown between the two clipped substrates in a size of 1.5 cm x 1.5 cm. After growth, the substrates with perovskite films were physically separated and directly used to collect XRD signals. It was found that after 5 month exposure to ambient air with 20% RH at room temperature, there was no change observed for XRD pattern of MAPbBr3 SCTF, indicating its excellent air stability. It should be noted that the weak diffraction from (110) planes at ~21 o in the XRD pattern could be ascribed to two possible reasons: 1) Since the X-ray beam of our Rigaku D diffractometer was not focused beam, the scanning area was much larger than the size of our SCTF (in a submillimeter scale). As we used a solution method to grow single crystalline film, there were some inevitable crystalline grains scattered at the edges of substrate which could be scanned to give the signal of (110) planes. 2) The as-grown single crystalline films might be split and lifted from the substrate to some extent upon the separation of the substrates, resulting in the exposure of (110) planes. The single-crystalline nature of the film has been confirmed by the synchrotron X-ray diffraction experiments. S9

10 Figure S9. Steady-state absorption spectra and optical bandgaps of: a,b) MAPbCl3 SCTF; c,d) MAPbI3 SCTF. S10

11 The measurement of carrier lifetime ( ) of the MAPbI 3 SCTF In order to further evaluate the optoelectronic quality of the prepared perovskite films, the carrier lifetime ( ) of MAPbI3 SCTF was measured by impedance spectroscopy (IS) technique (Fig. S7) as that reported by Huang et. al. 1 IS spectrum was recorded on the device with the structure of Au/perovskite SCTF/TiO2/FTO as illustrated in Figure S10a under 1 sun illumination at open circuit condition. The measured IS spectrum (Figure S10b) can be well-fitted by the widely used equivalent circuit (inset in Figure S10b). The of MAPbI3 SCTF was calculated to be 84 s, which is well consistent with that of the bulk MAPbI3 single crystal (98 s), 1 indicating its high optoelectronic quality. Figure S10. a) Device structure of MAPbI3 SCTF for impedance spectroscopy measurement. b) IS spectrum and equivalent circuit of MAPbI3 SCTF device. Ref. 1: Dong, Q.; Fang, Y.; Shao, Y.; Mulligan, P.; Qiu, J.; Cao, L.; Huang, J. Science 2015, 347, S11