Supporting information Efficient Inorganic Perovskite Light-Emitting Diodes with Polyethylene Glycol Passivated Ultrathin CsPbBr 3 Films Li Song,, Xiaoyang Guo, *, Yongsheng Hu, Ying Lv, Jie Lin, Zheqin Liu,, Yi Fan, and Xingyuan Liu *, State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China University of Chinese Academy of Sciences, Beijing 100049, China Corresponding Author: *E-mail: guoxy@ciomp.ac.cn; liuxy@ciomp.ac.cn S1
Figure S1. (a) Cross-sectional AFM profile of the scratched PEDOT:PSS film. (b) Cross-sectional AFM profile of the scratched PEDOT:PSS/PEG:CsPbBr 3 film. S2
Figure S2. Relationship between EQE and current density for the PeLEDs with different PEG:CsPbBr 3 (CsBr:PbBr 2 molar ratio of 1.4:1) weight ratios. S3
Figure S3. XRD patterns of the CsPbBr 3 and PEG:CsPbBr 3 films. S4
Figure S4. (a) J-V (b) L-V (c) CE-V and (d) EQE-V curves for the PeLEDs with different CsBr:PbBr 2 molar ratios at fixed PEG doping weight ratio of 3.4%. S5
Figure S5. Time-resolved PL decay curves for CsPbBr 3 and PEG:CsPbBr 3 (CsBr:PbBr 2 molar ratio of 1.86) films. S6
Figure S6. (a) J-V-L, (b) current efficiency-v, (c) EQE-V and (d) EL curves for the red PeLEDs with and without PEG doping. The CsBr:PbI 2 molar ratio in CsPbBr x I 3-x is 1.7:1 and the weight ratio of PEG: CsPbBr x I 3-x is 4.08%. Calculation of the weight ratio of PEG: CsPbBr x I 3-x : Perovskite solution (CsBr (86 mg) and PbI 2 (110 mg) in 1 ml DMSO) and PEG solution were first prepared as stock solutions. Before spin coating, these two solutions were mixed (perovskite: PEG= 10: 4 v/v) to form transparent precursor solution. The optimized PEG concentration is 20 mg/ml for the PEG: CsPbBr x I 3-x PeLED. Therefore, the weight ratio of PEG: CsPbBr x I 3-x is 4.08%. S7
Table S1. The PLQYs for CsPbBr 3 films with different CsBr:PbBr 2 molar ratios. CsBr:PbBr 2 1.4:1 1.54:1 1.69:1 1.77:1 1.86:1 1.95:1 PLQY (%) 34.9 36.8 40.4 56.5 62.7 33.8 S8
Table S2. PL lifetime of CsPbBr 3 and PEG:CsPbBr 3 films with CsBr:PbBr 2 molar ratio of 1.4:1 and 1.86:1, respectively. CsBr:PbBr 2 molar ratio 1.4:1 1.86:1 PEG weight ratio (%) 0 3.4 0 3.4 Fitting model (exponential decay) Tri- (ns) 1.55 2.12 2.38 2.6 (%) 79.72 45.07 65.47 25.16 (ns) 9.57 18.9 11.14 32.14 (%) 13.05 25.5 26.27 19.10 (ns) 34.73 111.9 43.95 297.56 (%) 7.32 29.43 8.27 55.73 0.811 1.122 0.697 1.107 (ns) 5.03 38.71 8.12 172.62 The decay curves for all the perovskite films can be best represented by the tri-exponential model : A(t)= exp(-t/τ 1 )+ exp(-t/τ 2 )+ exp(-t/τ 3 ) The multi-exponential decay curve reflects the presence of trap centers as the reference reported. 1, 2 The fastest decay component (τ 1 ) may relate to well-known surface or bulk defects assisted recombination. The second fastest decay component (τ 2 ) is the bimolecular recombination in the CsPbBr 3 bulk crystal and the slowest decay (τ 3 ) is relevant to the radiative recombination of free-carriers. The average life time was calculated by the equation: τ avg =τ 1 +τ 2 +τ 3 S9
Table S3. Summary of the representative CsPbBr 3 based PeLEDs. Perovskite emitter/thickness (nm) CsPbBr 3 thin film/30 nm CsPbBr 3 thin film/70 nm EL peak ( nm) V on (V) L max (cd/m 2 ) Max. EQE (%) Max. CE (cd/a) 522 2.5 36600 5.34 19.0 521 2.5 53525 4.26 15.67 CsPbBr 3 thin film/na 527 NA 10700 0.93 2.90 CsPbBr 3 thin film/na 528 3V 407 NA 0.035 CsPbBr 3 thin film/ NA 527 2.8 7267 0.15 0.57 CsPbBr 3 NCs/ 40 nm 516 3.5 1377 0.06 0.19 CsPbBr 3 QDs/ NA 512 3.4 15185 6.27 13.3 Ref This work 3 4 5 6 7 8 QDs (quantum dots), NCs (nanocrystals), V on (turn on voltage), L max (maximum luminance), NA (not available) S10
Table S4. Parameters for the CsPbBr x I 3-x red PeLEDs. The CsBr:PbI 2 molar ratio in CsPbBr x I 3-x is 1.7:1 and the weight ratio of PEG: CsPbBr x I 3-x is about 4%. Pervoskite L max Max. CE Max. EQE V on Voltage @ L max emitter (cd/m 2 ) (cd/a) (%) (V) (V) CsPbBr x I 3-x 136 7.57*10-3 9.58*10-3 5.4 8.6 PEG:CsPbBr x I 3-x 563 1.42*10-1 2.54*10-1 3.5 6.2 S11
REFERENCES: (1) Mondal, N.; Samanta, A. Complete Ultrafast Charge Carrier Dynamics in Photo-Excited All-Inorganic Perovskite Nanocrystals (CsPbX 3 ). Nanoscale 2017, 9, 1878-1885. (2) Zhao, P.; Yin, W.; Kim, M.; Han, M.; Song, Y. J.; Ahn, T. K.; Jung, H. S. Improved Carriers Injection Capacity in Perovskite Solar Cells by Introducing a-site Interstitial Defects. J. Mater. Chem. A 2017, 5, 7905-7911. (3) Ling, Y.; Tian, Y.; Wang, X.; Wang, J. C.; Knox, J. M.; Perez-Orive, F.; Du, Y.; Tan, L.; Hanson, K.; Ma, B., et al. Enhanced Optical and Electrical Properties of Polymer-Assisted All-Inorganic Perovskites for Light-Emitting Diodes. Adv. Mater. 2016, 28, 8983-8989. (4) Zhang, X.; Wang, W.; Xu, B.; Liu, S.; Dai, H.; Bian, D.; Chen, S.; Wang, K.; Sun, X. W. Thin Film Perovskite Light-Emitting Diode Based on CsPbBr 3 Powders and Interfacial Engineering. Nano Energy 2017, 37, 40-45. (5) Yantara, N.; Bhaumik, S.; Yan, F.; Sabba, D.; Dewi, H. A.; Mathews, N.; Boix, P. P.; Demir, H. V.; Mhaisalkar, S. Inorganic Halide Perovskites for Efficient Light-Emitting Diodes. J. Phys. Chem. Lett. 2015, 6, 4360-4364. (6) Wei, Z.; Perumal, A.; Su, R.; Sushant, S.; Xing, J.; Zhang, Q.; Tan, S. T.; Demir, H. V.; Xiong, Q. Solution-Processed Highly Bright and Durable Cesium Lead Halide Perovskite Light-Emitting Diodes. Nanoscale 2016, 8, 18021-18026. (7) Zhang, X.; Lin, H.; Huang, H.; Reckmeier, C.; Zhang, Y.; Choy, W. C. H.; Rogach, A. L. Enhancing the Brightness of Cesium Lead Halide Perovskite S12
Nanocrystal Based Green Light-Emitting Devices through the Interface Engineering with Perfluorinated Ionomer. Nano Lett. 2016, 16, 1415-1420. (8) Li, J.; Xu, L.; Wang, T.; Song, J.; Chen, J.; Xue, J.; Dong, Y.; Cai, B.; Shan, Q.; Han, B., et al. 50-Fold EQE Improvement up to 6.27% of Solution-Processed All-Inorganic Perovskite CsPbBr 3 QLEDs Via Surface Ligand Density Control. Adv. Mater. 2017, 29, 1603885. S13