Efficient and High-Color-Purity Light-Emitting Diodes Based on In-Situ Grown Films of CsPbX 3 (X = Br, I) Nanoplates with Controlled Thicknesses

Transcription

1 Supporting Information Efficient and High-Color-Purity Light-Emitting Diodes Based on In-Situ Grown Films of CsPbX 3 (X = Br, I) Nanoplates with Controlled Thicknesses Junjie Si, Yang Liu, Zhuofei He, Hui Du, Kai Du, ǂ Dong Chen, Jing Li, ǁ Mengmeng Xu, He Tian, ǂ Haiping He, ǁ Dawei Di, + Changqing Lin, Yingchun Cheng, Jianpu Wang, and Yizheng Jin * These authors contributed equally to this work. State Key Laboratory of Silicon Materials, Centre for Chemistry of High-Performance & Novel Materials, School of Materials Science and Engineering, Centre for Chemistry of High-Performance & Novel Materials, State Key Laboratory of Silicon Materials, Department of Chemistry, ǂ Center of Electron Microscope, State Key Laboratory of Silicon Material, School of Material Science and Engineering, ǁ State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou , China. + Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK. Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Centre for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech), 30 South Puzhu Road, Nanjing 1

2 211816, China. Figure S1. A histogram of thicknesses of the perovskite films measured from cross-sectional TEM images. The average thickness and standard deviation are 9.1 and 1.0 nm, respectively. 2

3 a c b d e Figure S2. Additional HRTEM images of the cross-sectional sample. From a to e are HRTEM images of the cross-sectional sample from which n value are extracted. Scale bar: 5 nm. 3

4 b c d e a Figure S3. Additional HRTEM analyses on the perovskite nanoplates transferred onto a copper grid. FFT patterns show that the crystal structure of all the selected crystals matches that of γ-cspbbr3. Scale bar: 5 nm. 4

5 Normalized Reflectivity (a.u.) PBABr 1495 Partly destroyed perovskite Perovskite Wavenumber (cm -1 ) Figure S4. Grazing-angle FTIR spectra of PBABr (black), a CsPbBr 3 -nanoplate film (blue) and a re-crystallized CsPbBr 3 film (red). All samples were deposited onto gold-coated quartz substrates. For the PBABr sample, absorption peaks at ~1497 and ~1505 cm -1 are assigned as skeletal stretching modes of aromatic phenyl group 1. For the CsPbBr 3 -nanoplate film, two broadened absorption peaks at ~1475 and ~1495 cm -1 shifted to lower wavenumbers. We suspect that these two peaks originate from the PBA cations passivating the perovskite surfaces. In this regard, we conducted additional experiment. The perovskite film was dissolved by dropping ethanol (1 ml) onto the substrate. Then ethanol was evaporated and the perovskite film was re-crystallized. This process should partially destroy the perovskite structure and release PBABr, if PBA cations existed in the perovskite film. FTIR analyses on such a re-crystallized perovskite film show that the two peaks at ~1475 and ~1495 cm -1 emerges. Based on these results, we conclude that the PBA cations exist in the CsPbBr 3 -nanoplate film. 5

6 a b Figure S5. Computational simulation of the layered PBA 2 (CsPbBr 3 ) n-1 PbBr 4 perovskites. a) Schematic representation of the crystal structure of the layered perovskite with n =6. Blue, yellow, red, purple, and gray balls represent Cs, Pb, Br, N, and C atoms, respectively. b) Calculated values of bandgaps for the perovskites with n from 6 to 18. 6

7 Figure S6. a) Temperature-dependent PL and b) Temperature-dependent PL decay of a TCQW CsPbBr 3 film. c) Temperature-dependent PL intensities. The radiative recombination lifetime ( ) were extracted from the PL decay data and PL QYs. The PL transient data can be fitted by a 3-exponential decay with Goodness-of-Fit of < 1.2: 7

8 where and are normalized coefficients and time constants, respectively. The average lifetime of the excited species,, can be expressed as: 1 + where and are radiative and non-radiative rate constants, respectively. PL QY can be determined by and : Therefore can be calculated as: + 8

9 Figure S7. A typical AFM height image of the ITO/NiO/TFB/PVK substrate. 9

10 a b Figure S8. The impacts of concentrations of PBABr in the precursor solutions on the properties of the resulting perovskite films. a) PL spectra and PL QYs and b) XRD patterns. 10

11 a b c Figure S9. a) PL spectra, b) PL decay curves and c) PL QYs of the perovskite films grown onto different substrates. 11

12 Figure S10. UPS spectrum of a TCQW CsPbBr 3 film. 12

13 Figure S11. CIE coordinates of green and red PeLEDs based on the TCQW CsPbBr 3 films and the TCQW CsPbI 3 films, respectively. 13

14 Intensity (a.u.) Wavelength (nm) Figure S12. EL spectrum of a control device without perovskite layer (structure: ITO/NiO/TFB/PVK/TPBi/Ca/Al). 14

15 Figure S13. EQE-Luminance and V-J-L curves of the champion device with a peak EQE of 10.4%. 15

16 a b Figure S14. Device characteristics of a 56-mm 2 TCQW CsPbBr 3 LED. a) Current density luminance voltage curves. b) Peak EQEs of this 56-mm 2 device as a function of time of storage in a nitrogen-filled glovebox. 16

17 a b Figure S15. a) EL spectrum and b) a histogram of peak EQEs for 16 devices of red TCQW CsPbI 3 PeLEDs. 17

18 Table S1. Comparison of our TCQW CsPbBr 3 LED with other green PeLEDs Emitters EL Peak Max EQE Max current Max luminous FWHM Reference (nm) (%) efficiency (Cd/A) efficacy (lm/w) (mev) CsPbBr 3 TCQW This work CsPbBr 3 QD CsPbBr 3 QD CsPbBr 3 QD CsPbBr 3 QD MAPbBr 3 nanoplates NFPB 7 MQW PEABr:MAPbBr 3 MQW BABr:MAPbBr 3 nanocrystallites MAPbBr 3 in-situ nanocrystallites Quasi-2D MAPbBr ~ ~ ~520 ~ MAPbBr 3 film MAPbBr 3 film FAPbBr 3 film CsPbBr composites MAPbBr 3 film CsPbBr 3 composites Cs 0.4 MA 0.6 PbBr 3 film

19 REFERENCES 1. Li, W. J.; Lynch, V.; Thompson, H.; Fox, M. A. Self-Assembled Monolayers of 7-(10-thiodecoxy)coumarin on Gold: Synthesis, Characterization, and Photodimerization. J. Am. Chem. Soc. 1997, 119,