Supporting Information CsPbIBr 2 Perovskite Solar Cell by Spray Assisted Deposition Cho Fai Jonathan Lau, Xiaofan Deng, Qingshan Ma, Jianghui Zheng, Jae S. Yun, Martin A. Green, Shujuan Huang, Anita W. Y. Ho-Baillie The Australian Centre for Advanced Photovoltaics, School of Photovoltaic and Renewable Energy Engineering, University of New South Wales(UNSW), Sydney, NSW 2052, Australia. Corresponding Author: Anita Ho-Baillie, a.ho-baillie@unsw.edu.au
EXPERIMENTAL SECTION Perovskite film deposition and characterization: For the fabrication of test structures for characterization, perovskite films are deposited on mesoporous (mp-)tio2 /blocking (bl-)tio2/fto/glass. The 1M lead bromide(alfa Aesar) precursor solution in anhydrous DMF:DMSO 3:2 (v:v) was heated up to 80 C until fully dissolved and was then spin coated on the mesoporous TiO2 substrate at 5000rpm for 30s. After that, 150µL of 45mg/ml cesium iodide (CsI) (Sigma Aldrich) in methanol at 90 C was sprayed on the lead bromide substrate in air at different temperature (room temperature, 160 C and 350 C) using Iwata Custom Micron C plus hand spray. The distance between the hand spray nozzle and the substrate was 5cm and the spray pressure was 2psi. The substrate was then annealed at different temperature (275 C, 300 C, 325 C and 350 C) for 10min to crystalize the film in air. Energy dispersive X-ray spectroscopy (EDS) measurements were carried out by the NanoSEM 230 using a Bruker SDD-EDS detector. X-ray diffraction (XRD) patterns were measured using a PANalytical Xpert Materials Research diffractometer system with a Cu Kα radiation source ( λ = 0.1541 nm) at 45 kv and 40 ma. Top view and cross-sectional scanning electron microscopy (SEM) images were obtained using a field emission SEM (NanoSEM 230). The optical reflection and transmission spectra were measured using Perkin Elmer Lambda1050 UV/Vis/NIR spectrophotometer. Time-Correlated Single Photon Counting (TCSPC) measurements were conducted on a confocal laser scanning microscope (Leica SP5 WLL STED) with excitation at 488 nm from pulsed white light laser and repetition rate of 20 MHz. The power intensity is ~ 100 mw/cm2. The 100 oil objective (n=1.4) was used and the imaging resolution is 1024 1024. A low scan speed of 100 Hz was used to reduce the noise. The experiment was undertaken at room temperature. Device fabrication and characterization:
For the fabrication of full device, patterned FTO-coated glass (Nippon Sheet Glass, TEC10, 10 Ω -1 sheet resistivity) was cleaned by sonication in deionized water with 2% Hellmanex, acetone and isopropanol for 20 min. After drying, the substrate was treated by UV ozone cleaner for 20 min. To form the compact TiO2 blocking layer (bl-tio2), a solution of titanium diisopropoxide bis(acetylacetonate) in ethanol was deposited on the clean substrates by spray pyrolysis at 400 C and the substrate was subsequently annealed on a hot plate at 400 C for 20 min. For mesoporous structure, 200nm mp-tio2 layer was deposited by spin coating for 30s for 5500rpm, using a Dyesol 18 NR-T paste with a 1:6 dilution in ethanol. After spin coating, the substrate was dried at 100 C for 10 min and then annealed at 500 C for 30min. For the formation of perovskite film, same deposition and annealing processes were carried out as described above. The hole transporting precursor solution was prepared by dissolving 72.3mg (2,2,7,7 -tetrakis(n,ndi-p-methoxyphenylamine)-9,9-spirobifluorene) (spiro-meotad) (Lumtec), 28.8 µl 4-tertbutylpyridine (Sigma Aldrich) and 17.5 µl lithium bis(trifluoromethylsulphonyl)imide (Sigma Aldrich) solution (520mg/mL in acetonitrile) in 1 ml chlorobenzene (Sigma Aldrich) and was deposited on CsPbIBr2 by spin coating at 4000rpm for 20s. Finally, 100nm of gold was thermally evaporated on spiro-meotad to form the top electrode. The current density voltage (J V) measurements were performed using a solar cell I V testing system from Abet Technologies, Inc. (using class AAA solar simulator) under an illumination power of 100 mw cm-2 with an 0.159 cm2 aperture and a scan rate of 30mV s -1. The external quantum efficiency (EQE) measurement was carried out by the PV Measurement QXE7 Spectral Response system with monochromatic light from a xenon arc lamp.all measurements were undertaken at room temperature in ambient condition.
Figure S1. Absorption coefficients of the CsPbIBr 2 films on mp- TiO 2 /bl- TiO 2 /FTO glass annealed at different temperatures.
Device Jsc [macm-2] Voc [mv] FF [%] PCE [%] Scan Mesoporous Planar HTM-free 7.8 1127 72 6.3 Reverse 7.9 1121 70 6.2 Forward 5.1 1119 56 3.2 Reverse 5.2 1108 31 1.8 Forward 5.7 794 59 2.6 Reverse 5.4 873 32 1.5 Forward Figure S2. Current density- voltage (J- V) characteristics of CsPbIBr 2 cells of different structures: Au/Spiro- OMeTAD/CsPbIBr 2 /mp- TiO 2 /bl- TiO 2 /FTO glass, (solid line for mesoporous ), Au/Spiro- OMeTAD/CsPbIBr 2 /bl- TiO 2 /FTO glass (dash line for planar ), and Au/CsPbIBr 2 /mp- TiO 2 /bl- TiO 2 /FTO glass (dotted line for HTM- free ) measured under reverse scan (V OC to J SC ) and forward scan (J SC to V OC )
Figure S3. (a) XRD patterns (b) Photos of the CsPbIBr 2 films before and after heat treatment at 300 C for 1.5 hours in a glove box.