Non-template Synthesis of CH 3 NH 3 PbBr 3 Perovskite Nanoparticles

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1 Non-template Synthesis of CH 3 NH 3 PBr 3 Perovskite Nanoparticles Luciana C. Schmidt, a Antonio Pertegás, a Soranyel González-Carrero, a Olga Malinkiewicz, a a Said Agouram, Guillermo Mínguez Espallargas, a Henk J. Bolink, a Raquel E. Galian, a* and Julia Pérez- Prieto a* a Instituto de Ciencia Molecular (ICmol), Universidad de Valencia, Catedrático José Beltrán 2, 4698, Paterna, Valencia, Spain. Fax: ; Tel: ; raquel.galian@uv.es, julia.perez@uv.es Department of Applied Physics and Electromagnetism, University of Valencia, Edif. Investigación, c/ Dr. Moliner 5, 461, Burjassot, Spain. Supplementary Information Material and methods Figure S1: Asorption and emission spectra of P ODA1 Figure S2 : Asorption and emission spectra of P ODA2 Figure S3: Asorption and emission spectra of P ODA3 Figure S4: TEM images of P ODA1 Figure S5: TEM images of P ODA2 Figure S6: TEM images of P ODA3 Figure S7: Photographs of P OA2 and P OAD2 in toluene under amient light and UV-light. Figure S8. Room-temperature fluorescence intensity of P OA2 in toluene as a function of the illumination time and sample irradiation y using a fluorimeter excitation. Figure S9: Photographs of the solutions otained after solid P OA2 (2 mg) was dispersed in different organic solvents (1 ml) Figure S1. Oserved (lue) and calculated (red) profiles and difference plot [(I os I calcd )] (green) of the X-ray powder diffraction Pawley refinement for P OA 2. Tale S1: XRD parameters of P OA2 Figure S11. TEM images of P OA 2.Inset in c: zoom of two NPs. Figure S12. Current density and room-temperature luminance versus applied voltage for device type I (ITO/Al 2 O 3 \n-perovskite/sppo13/ba/ag) and type II (ITO/PEDOT:PSS/pTPD/P OA2 /Ba/Ag). Figure S11. TEM images of ODA-capped CH 3 NH 3 PI 3 nanoparticles. S2-S4 S5 S6 S7 S8 S9 S1 S11 S12 S13 S14 S14 S15 S16 S17 S1

2 MATERIAL AND METHODS Materials All commercial materials were used as received: aqueous dispersion of poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS, CLEVIOS P VP Al 483 (Heraeus); Aluminum oxide nanoparticles, <5 nm particle size (DLS), 2 wt. % in isopropanol (Aldrich); SPPO13 (2,7-is(diphenylphosphoryl)-9,9 -spiroi[fluorene], Luminescence Technology Corp.) and ptpd (Poly[N,N'-is(4-utylphenyl)-N,N'-is(phenyl)-enzidine], American Dye Source Inc.). All the reagents used in the synthesis of the perovskites and the alkyl ammonium romides were purchased from Aldrich and used as received. The organic solvents were of spectroscopic grade (Scharla). The precursors, methylammonium romide (CH 3 NH 3 Br) and octylammonium romide (CH 3 (CH 2 ) 7 NH 3 Br), were synthesized y reaction of the corresponding amine in water/hbr, accordingly to the previously reported procedure. 1 In the case of octadecylammonium romide (CH 3 (CH 2 ) 17 NH 3 Br), it was prepared y using a similar methodology ut the amine was previously dissolved in acetonitrile at 6 C and then HBr was added. In all cases, the precipitate was washed several times with diethyl ether, dried under vacuum and used without further purification. Synthesis of P ODA1. A solution of oleic acid (85 mg,.3 mmol) in 2 ml of octadecene was stirred and heated at 8 C and then, octadecylammonium romide (17.5 mg,.5 mmol) was added. Susequent addition of methylammonium romide (5.5 mg,.5 mmol dissolved in 1 µl of DMF) and lead(ii) romide (36.7 mg,.1 mmol dissolved in 1 µl of DMF) produced a yellow dispersion from which the nanoparticles were immediately precipitated y addition of acetone followed y centrifugation (7 rpm, 1 min). Finally, the nanoparticles were dispersed in toluene. Synthesis of P ODA2. The same procedure than for P ODA1 was followed, except that the quantity of octadecylammonium romide and methylammonium romide was 21 mg (.6 mmol) and 4.4 mg (.4 mmol), respectively. Synthesis of P ODA3. The same procedure than for P ODA1 was followed, except that the quantity of octadecylammonium romide and methylammonium romide was 24.5 mg (.7 mmol) and 3.3 mg (.3 mmol), respectively. Synthesis of P OA2. A solution of oleic acid (85 mg,.3 mmol) in 2 ml of octadecene was stirred and heated at 8 C and then, octylammonium romide (12.6 mg,.6 mmol) was added. Susequent addition of methylammonium romide (4.4 mg,.4 mmol dissolved in 1 µl of DMF) and lead(ii) romide (36.7 mg,.1 mmol dissolved in 1 µl of DMF) produced a yellow dispersion from which the nanoparticles were immediately precipitated y addition of acetone followed y centrifugation (7 rpm, 1 min). Finally, the nanoparticles were dispersed in S2

3 toluene. Film preparation. Quartz sustrates were extensively cleaned using detergent, de-mineralized water, and isopropyl alcohol, respectively, followed y 9 min UV-ozone treatment and 1 min of oxygen plasma cleaning in order to enhance good thin film formation. A colloidal solution of P OA2 perovskite in toluene was spin-coated on top of the quartz sustrates with 1 rpm during 3 sec resulting in film thickness of ca. 2-3 nm. Characterization Methods UV-visile spectra of the samples were recorded using a quartz cuvettes spectrometer in a UV-visile spectrophotometer Agilent 8453E. Steady-state fluorescence spectra were measured on a Amnico Browman series 2 Luminescence spectrometer, equipped with a lamp power supply and working at room temperature. The AB2 software (v. 5.5) was used to register the data. All the data were acquired using 1cm 1cm path length quartz cuvettes, using an excitation wavelength of 35 nm. Transmission electron microscopy TEM, high resolution TEM (HRTEM), selected area electron diffraction, and energy dispersive X-ray spectroscopy EDS in nanoproe mode was carried out y using a Field Emission Gun (FEG) TECNAI G 2 F2 microscope operated at 2 kv. TEM samples were prepared from a toluene dispersion of the NPs, and a few drops of the resulting suspension were deposited onto a caron film supported on a copper grid, which was susequently dried. The electroluminescent devices were made as follows. Indium tin oxide ITO-coated glass plates were patterned y conventional photolithography (Naranjo Sustrates). The sustrates were cleaned ultrasonically in water-soap, water and 2-propanol aths. After drying, the sustrates were placed in a UV-ozone cleaner (Jelight 42-22) for 2 min. Next layers were prepared as follows: Type 1: A layer of Al 2 O 3 nanoparticles was coated y spin-coating on ITO at 2 rpm from a dispersion of 1:2 isopropanol:ethanol v/v. After that, the sample was sintered at 3ºC during 2 hours. The perovskite layer was coated using a two-step process: a) A solution of 5 mg/ml in DMF of PBr 2 was spin-coated at 15 rpm on the Al 2 O 3 nanoparticle layer ) the sustrate was dipped in a methyl ammonium romide solution (1 mg/ml in 2-propanol). The SPPO13 layer was prepared from a solution of 1 mg/ml in anisole at 1 rpm for 6s. Type 2: An 8 nm layer of PEDOT:PSS was spin-coated on the ITO-glass sustrate. After that, a chloroenzene solution of 7 mg/ml was used to coat the ptpd layer at 2 rpm during 3 s. The layer was annealed at 18ºC for 3 minutes and after that, the samples were washed 3 times with chloroenzene at 2 rpm. The pervoskite layer was prepared from POA2 nanoparticles in toluene (4 mg/ml). S3

4 Finally, all the devices were transferred into an inert atmosphere glove-ox, where the arium/silver electrode was thermally evaporated using a shadow mask. The size of the device was 6.5 mm 2. The thickness of the films was determined with an Amios XP-1 profilometer. Thin film photoluminescence spectra and quantum yields were measured with a Hamamatsu C992-2 Asolute PL Quantum Yield Measurement System. It consists of an excitation light source (a xenon lamp linked to a monochromator), an integration sphere and a multi-channel spectrometer. Current density and luminance versus voltage sweeps were measured y using a Keithley 24 source meter and a photodiode coupled to the Keithley 6485 pico-amperometer calirated using a Minolta LS1 luminance meter. Electroluminescence spectra were recorded with an Avantes fier-optics photo-spectrometer. The devices were not encapsulated and were characterized inside the gloveox. Staility tests of toluene colloidal solutions of P OA 2 under light illumination Test 1. A toluene colloidal solution of P OA 2 was irradiated for up to 6 min, using 1 x 1 mm quartz cuvette placed in a Luzchem photoreactor equipped with eight UV-A lamps (316-4 nm, maximum at 351 nm). The room-temperature fluorescence of the sample (λ exc = 35 nm, λ em = 528 nm) was recorded every 3 min. Test 2. A toluene colloidal solution of P OA 2 was illuminated for up to 16 min, using 1 x 1 mm quartz cuvette placed in the sample-holder of a PTI- LPS-22B spectrometer equipped with a Xenon lamp (75 W). The Felix 32 analysis software was used to register the data. S4

5 .5 a.4.3 As wavelength, nm 3.5 Fluorescence (a.u) wavelength, nm Figure S1. Asorption (a) and room-temperature emission () spectra of P ODA1 in toluene (λ exc = 35 nm; λ em = 393, 457 nm, 475 nm, 529 nm; FWHM = 26 nm) S5

6 .8 a.6 As wavelength, nm 5.2 Fluorescence (a.u) wavelength, nm Figure S2. Asorption (a) and room-temperature emission spectra () of P ODA2 in toluene (λ exc = 35 nm; λ em = 395 and 526 nm; FWHM = 24 nm) S6

7 .5 a.4.3 As wavelength, nm 7 Fluorescence (a.u) wavelength, nm Figure S3. Asorption (a) and room-temperature emission () spectra of P ODA3 in toluene (λ exc = 35 nm; λ em = 395 and 524 nm; FWHM = 23 nm) S7

8 a c d Figure S4. TEM images of P ODA1, scale ar:.5 µm (a),.2 µm (), 1 nm (c) and 2 nm (d). S8

9 a c d Figure S5. TEM images of P ODA2, scale ar: 5 nm (a), 5 nm (), 2 nm (c) and 2 nm (d). S9

10 a c d Figure S6. TEM images of P ODA3, scale ar:.1 µm (a), 5nm (), 2 nm (c) and 1 nm (d). S1

11 a P OA2 P ODA2 P OA2 P ODA2 Figure S7. Photographs of P OA2 and P OAD2 in toluene under la light (a) and UV-light (). S11

12 1 Fluorescence intensity (a.u) Fluorescence intensity (a.u) t= t= 6 min wavelength, nm time, min 4 Fluorescence intensity (a.u) Fluorescence intensity (a.u) min 16 min wavelength, nm Time (min) Figure S8. Room-temperature fluorescence intensity of P OA2 in toluene (λ em = 528 nm) as a function of the illumination time. Top: the sample was irradiated y using eight UVA lamps (intensity 5.3 mw.cm -2 ); inset: fluorescence spectra of the sample (λ exc = 35 nm; λ em = 528 nm) efore and after 6 minutes irradiation. Bottom: the sample was continuously irradiated y using a fluorimeter excitation lamp (λ exc = 35 nm); inset: fluorescence spectra of the sample (λ exc = 35 nm; λ em = 528 nm) efore and after 16 minutes of illumination. S12

13 Dispersiility of P OA2 in organic solvents Aprotic solvent Protic Solvent Hexa Tolue THF Dioxa Chlorof Aniso Ethyl DMS Iso- Solvent Figure S9. Photographs of the solutions otained after solid P OA2 (2 mg) was dispersed in different organic solvents (1 ml); methanol led to the same result to isopropanol (this photograph has not een included). S13

14 θ (deg) Figure S1. Oserved (lue) and calculated (red) profiles and difference plot [(I os I calcd )] (green) of the X-ray powder diffraction Pawley refinement for P OA2 (λ = Cu K α, 2θ range ); tick marks indicate peak positions for P OA2 (see Tale S1). Tale S1: XRD parameters of P OA2 (λ = Cu K α ) hkl d (Å) 2-theta ( ) S14

15 A a c d Figure S11. TEM images of P OA2 ; scale ar: 5 nm (a), 2 nm () and 5 nm (c, d). Inset in c: zoom of two NPs. S15

16 Current Density [A/m 2 ] E Luminance [cd/m 2 ] 1E Voltage [V] Figure S12. Current density (red solid squares) and room-temperature luminance (open symols) versus applied voltage for device type I (ITO/Al 2 O 3 \n- Perovskite/SPPO13/Ba/Ag; lue down triangles) and type II (ITO/PEDOT:PSS/pTPD/ P OA2 /Ba/Ag; green up triangles). S16

17 a c d Figure S13. TEM images of ODA-capped CH 3 NH 3 PI 3 nanoparticles synthesized y performing small variations on the strategy reported in the manuscript, scale ar: 2 nm (a, ) and 5 nm (c, d). (1) Papavassiliou, G. C.; Pagona, G.; Karousis, N.; Mousdis, G. A.; Koutselas, I.; Vassilakopoulou, A. Journal of Materials Chemistry 212, 22, S17