High-Efficiency Organic Light-Emitting Diodes Based on Sublimable Cationic Iridium(III) Complexes with Sterically Hindered Spacers

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1 Supporting Information High-Efficiency Organic Light-Emitting Diodes Based on Sublimable Cationic Iridium(III) Complexes with Sterically Hindered Spacers Dongxin Ma 1 *, Ruihuan Liu 1, Chen Zhang 1, Yong Qiu 1, Lian Duan 1,2 * 1 Key Lab of Organic Optoelectronics & Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing , P. R. China. 2 Center for Flexible Electronics Technology, Tsinghua University, Beijing , P. R. China. madongxin1130@qq.com; duanl@mail.tsinghua.edu.cn Supplemental Experimental Section Pages S1-S61 Figures S1-S52 Tables S1-S3 S1

2 Supplemental Experimental Section Structural Characterization Methods. The ESI mass spectrometry was performed with Thermo Electron Corporation Finnigan LTQ. 1 H NMR and 19 F NMR spectra were recorded on a JOEL JNM-ECA600 NMR spectrometer. X-Ray Crystallography. The single crystal X-ray diffraction data collections were carried out on a Rigaku AFC-10/Saturn 724+ charge-coupled device (CCD) diffractometer equipped with graphite-monochromatized Mo Kα radiation (λ = Å) using the multi-scan technique. The structures were determined by direct methods using SHELXS-97 and refined by full-matrix least-squares procedures on F2 with SHELXL All the non-hydrogen atoms were obtained from the difference Fourier map and subjected to anisotropic refinement by full-matrix least squares on F2. The hydrogen atoms were obtained geometrically and treated as riding on the parent atoms or constrained in the locations during refinements. Photophysical, Electrochemical and Thermal Measurements. Absorption spectra was measured by an ultraviolet-visible spectrophotometer (Agilent 8453), while PL spectra were characterized by a fluorospectrophotometer (HITACHI, F-7000). PLQYs in solutions and neat films were measured at the excitation wavelength of 400 nm (Hamamutsu Photonics K. K., C ). The excited state lifetimes were measured by a lifetime and steady state spectrometer (Edinburgh Instruments, FLS 980) with time-correlated single-photon counting (TCSPC) technique at the corresponding emission wavelength. CV was probed in oxygen-free anhydrous solutions on a Princeton Applied Research potentiostat/ galvanostat Model 283 voltammetric analyzer at a scanning rate of 100 mv/s with a platinum plate as the working S2

3 electrode, a silver wire as the pseudo-reference electrode and a platinum wire as the counter electrode. The oxidation potentials were measured in N,N-dimethylformamide solutions with 40 mg/ml tetrabutylammonium perchlorate supporting electrolyte, while the reduction potentials were measured in acetonitrile solutions with 35 mg/ml tetrabutylammonium hexafluorophosphate supporting electrolyte. Ferrocene served as the internal standard. TGA was measured by a thermogravimetric analyzer (TA Instruments Q5000) with a heating rate of 10 o C/min under nitrogen-flow conditions. Quantum Chemical Calculations. Calculations on the volume of both the coordinated iridium(iii) cations and tetraphenylborate-type anions were performed by means of DFT using opt volume=tight rb3lyp/gen geom=connectivity pseudo=read. Calculations on the ground electronic states of the emissive coordinated iridium(iii) cations were performed by means of DFT using opt=tight rb3lyp/gen geom=connectivity pseudo=read. Calculations on the excited electronic states of the emissive coordinated iridium(iii) cations were performed by means of TD-DFT using td=(50-50,nstates=5) b3lyp/gen geom=connectivity pseudo=read. The doubleξ quality basis sets were 6-31G* for the carbon, hydrogen, nitrogen, fluorine and LANL2DZ for iridium. The inner core electrons of iridium(iii) were replaced by an effective core potential (ECP), with outer core of 5s 2 5p 6 electrons and the 5d 6 valence electrons. All the quantum chemical calculations were performed with Gaussian 09 software package using a spinrestricted formalism (see the reference). Device Fabrication and Evaluation. The OLEDs were grown on the cleaned, ultravioletozone-treated and ITO-coated glass substrates, with a sheet resistance of about 20 Ω per sq. S3

4 Each functional material layer was successively fabricated thereon by vacuum evaporation deposition under a low pressure below Pa. Current density-voltage and luminancevoltage curves were collected with Keithley 4200 semiconductor system, while the EL spectra were recorded by a Photo Research PR705 spectrophotometer. All the device measurements were carried out at room temperature in the ambient air without further encapsulations. Reference Frisch, M. J.; Trucks, G. W.; Schelegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A.; Jr., Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, O.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09, Revision B.01; Gaussian, Inc., Wallingford CT, S4

5 Figure S1. The synthetic routes of complexes 1-4. S5

6 Figure S2. The synthetic routes of complexes S6

7 Figure S3. The single-crystal structure of [Ir(ppy)2(bpy)][BF4] (complex 1). Here the thermal ellipsoids are drawn at the 30% probability level. The solvent molecules and hydrogen atoms are omitted for clarity. The unlabeled atoms are carbon atoms. Figure S4. The single-crystal structure of [Ir(ppy)2(bpy)][PF6] (complex 2). Here the thermal ellipsoids are drawn at the 30% probability level. The solvent molecules and hydrogen atoms are omitted for clarity. The unlabeled atoms are carbon atoms. S7

8 Figure S5. The single-crystal structure of [Ir(ppy)2(bpy)][B(5FPh)4] (complex 3). Here the thermal ellipsoids are drawn at the 30% probability level. The solvent molecules and hydrogen atoms are omitted for clarity. The unlabeled atoms are carbon atoms. Figure S6. The single-crystal structure of [Ir(ppy)2(bpy)][B(dCF3Ph)4] (complex 4). Here the thermal ellipsoids are drawn at the 30% probability level. The solvent molecules and hydrogen atoms are omitted for clarity. The unlabeled atoms are carbon atoms. S8

9 Figure S7. The single-crystal structure of [Ir(ppy)2(dtb-bpy)][B(5FPh)4] (complex 5). Here the thermal ellipsoids are drawn at the 30% probability level. The solvent molecules and hydrogen atoms are omitted for clarity. The unlabeled atoms are carbon atoms. Figure S8. The single-crystal structure of [Ir(ppy)2(dtb-bpy)][B(dCF3Ph)4] (complex 6). Here the thermal ellipsoids are drawn at the 30% probability level. The solvent molecules and hydrogen atoms are omitted for clarity. The unlabeled atoms are carbon atoms. S9

10 Figure S9. The single-crystal structure of [Ir(phq)2(dtb-bpy)][B(5FPh)4] (complex 7). Here the thermal ellipsoids are drawn at the 30% probability level. The solvent molecules and hydrogen atoms are omitted for clarity. The unlabeled atoms are carbon atoms. Figure S10. The single-crystal structure of [Ir(phq)2(dtb-bpy)][B(dCF3Ph)4] (complex 8). Here the thermal ellipsoids are drawn at the 30% probability level. The solvent molecules and hydrogen atoms are omitted for clarity. The unlabeled atoms are carbon atoms. S10

11 Figure S11. The single-crystal structure of [Ir(piq)2(dtb-bpy)][B(5FPh)4] (complex 9). Here the thermal ellipsoids are drawn at the 30% probability level. The solvent molecules and hydrogen atoms are omitted for clarity. The unlabeled atoms are carbon atoms. Figure S12. The single-crystal structure of [Ir(piq)2(dtb-bpy)][B(dCF3Ph)4] (complex 10). Here the thermal ellipsoids are drawn at the 30% probability level. The solvent molecules and hydrogen atoms are omitted for clarity. The unlabeled atoms are carbon atoms. S11

12 Figure S13. The packing view of [Ir(ppy)2(bpy)][BF4] (complex 1) along a direction. The shortest Ir-B and Ir-Ir distance is and Å, respectively. S12

13 Figure S14. The packing view of [Ir(ppy)2(bpy)][PF6] (complex 2) along a direction. The shortest Ir-P and Ir-Ir distance is and Å, respectively. S13

14 Figure S15. The packing view of [Ir(ppy)2(bpy)][B(5FPh)4] (complex 3) along a direction. The shortest Ir-B and Ir-Ir distance is and Å, respectively. S14

15 Figure S16. The packing view of [Ir(ppy)2(bpy)][B(dCF3Ph)4] (complex 4) along a direction. The shortest Ir-B and Ir-Ir distance is and Å, respectively. S15

16 Figure S17. The packing view of [Ir(ppy)2(dtb-bpy)][B(5FPh)4] (complex 5) along a direction. The shortest Ir-B and Ir-Ir distance is and Å, respectively. S16

17 Figure S18. The packing view of [Ir(ppy)2(dtb-bpy)][B(dCF3Ph)4] (complex 6) along a direction. The shortest Ir-B and Ir-Ir distance is and Å, respectively. S17

18 Figure S19. The packing view of [Ir(phq)2(dtb-bpy)][B(5FPh)4] (complex 7) along a direction. The shortest Ir-B and Ir-Ir distance is and Å, respectively. S18

19 Figure S20. The packing view of [Ir(phq)2(dtb-bpy)][B(dCF3Ph)4] (complex 8) along a direction. The shortest Ir-B and Ir-Ir distance is and Å, respectively. S19

20 Figure S21. The packing view of [Ir(piq)2(dtb-bpy)][B(5FPh)4] (complex 9) along a direction. The shortest Ir-B and Ir-Ir distance is and Å, respectively. S20

21 Figure S22. The packing view of [Ir(piq)2(dtb-bpy)][B(dCF3Ph)4] (complex 10) along a direction. The shortest Ir-B and Ir-Ir distance is and Å, respectively. S21

22 Figure S23. Absorption spectra of complexes 1-10 in anhydrous acetonitrile solutions. S22

23 Figure S24. PL spectra of complexes 1-10 in acetonitrile glass at 77 K. S23

24 Figure S25. Excited state lifetimes of complex 1 (a) in neat films at room temperature and (b) in acetonitrile glass at 77 K. S24

25 Figure S26. Excited state lifetimes of complex 2 (a) in neat films at room temperature and (b) in acetonitrile glass at 77 K. S25

26 Figure S27. Excited state lifetimes of complex 3 (a) in neat films at room temperature and (b) in acetonitrile glass at 77 K. S26

27 Figure S28. Excited state lifetimes of complex 4 (a) in neat films at room temperature and (b) in acetonitrile glass at 77 K. S27

28 Figure S29. Excited state lifetimes of complex 5 (a) in neat films at room temperature and (b) in acetonitrile glass at 77 K. S28

29 Figure S30. Excited state lifetimes of complex 6 (a) in neat films at room temperature and (b) in acetonitrile glass at 77 K. S29

30 Figure S31. Excited state lifetimes of complex 7 (a) in neat films at room temperature and (b) in acetonitrile glass at 77 K. S30

31 Figure S32. Excited state lifetimes of complex 8 (a) in neat films at room temperature and (b) in acetonitrile glass at 77 K. S31

32 Figure S33. Excited state lifetimes of complex 9 (a) in neat films at room temperature and (b) in acetonitrile glass at 77 K. S32

33 Figure S34. Excited state lifetimes of complex 10 (a) in neat films at room temperature and (b) in acetonitrile glass at 77 K. S33

34 Figure S35. CV of complexes 1-4 with [Ir(ppy)2(bpy)] + in oxygen-free anhydrous solutions. Ferrocence serves as the internal standard. Figure S36. CV of complexes 5 and 6 with [Ir(ppy)2(dtb-bpy)] + in oxygen-free anhydrous solutions. Ferrocence serves as the internal standard. S34

35 Figure S37. CV of complexes 7 and 8 with [Ir(phq)2(dtb-bpy)] + in oxygen-free anhydrous solutions. Ferrocence serves as the internal standard. Figure S38. CV of complexes 9 and 10 with [Ir(piq)2(dtb-bpy)] + in oxygen-free anhydrous solutions. Ferrocence serves as the internal standard. S35

36 Figure S39. TGA of complexes 1-10 under nitrogen-flow conditions. S36

37 Figure S40. The frontier MO surfaces of [Ir(ppy)2(bpy)] +, corresponding to an isocontour value of Ψ = 0.02 at the optimized geometry. The contribution of each mono-electronic excitation to T1 S0 and T2 S0 transitions is obtained by means of TD-DFT. All the hydrogen atoms are omitted for clarity. S37

38 Figure S41. The frontier MO surfaces of [Ir(ppy)2(dtb-bpy)] +, corresponding to an isocontour value of Ψ = 0.02 at the optimized geometry. The contribution of each mono-electronic excitation to T1 S0 and T2 S0 transitions is obtained by means of TD-DFT. All the hydrogen atoms are omitted for clarity. S38

39 Figure S42. The frontier MO surfaces of [Ir(phq)2(dtb-bpy)] +, corresponding to an isocontour value of Ψ = 0.02 at the optimized geometry. The contribution of each mono-electronic excitation to T1 S0 and T2 S0 transitions is obtained by means of TD-DFT. All the hydrogen atoms are omitted for clarity. S39

40 Figure S43. The frontier MO surfaces of [Ir(piq)2(dtb-bpy)] +, corresponding to an isocontour value of Ψ = 0.02 at the optimized geometry. The contribution of each mono-electronic excitation to T1 S0 and T2 S0 transitions is obtained by means of TD-DFT. All the hydrogen atoms are omitted for clarity. S40

41 S41

42 Figure S44. Molecular structures of the materials used in the OLEDs. S42

43 Figure S45. Characteristics of the OLEDs based on complex 3 in the structure of ITO/ HATCN (5 nm)/ NPB (40 nm)/ TCTA (10 nm)/ DIC-TRZ: x% complex 3 (12 nm)/ BPBiPA (50 nm)/ LiF (1 nm)/ Al (150 nm) at varying dopant concentrations. (a) Current density-voltage, (b) luminance-voltage and (c) current efficiency-luminance curves, (d) EL spectra. S43

44 S44

45 Figure S46. Characteristics of the OLEDs based on complex 4 in the structure of ITO/ HATCN (5 nm)/ NPB (40 nm)/ TCTA (10 nm)/ DIC-TRZ: x% complex 4 (12 nm)/ BPBiPA (50 nm)/ LiF (1 nm)/ Al (150 nm) at varying dopant concentrations. (a) Current density-voltage, (b) luminance-voltage and (c) current efficiency-luminance curves, (d) EL spectra. S45

46 S46

47 Figure S47. Characteristics of the OLEDs based on complex 5 in the structure of ITO/ HATCN (5 nm)/ NPB (40 nm)/ TCTA (10 nm)/ DIC-TRZ: x% complex 5 (12 nm)/ BPBiPA (50 nm)/ LiF (1 nm)/ Al (150 nm) at varying dopant concentrations. (a) Current density-voltage, (b) luminance-voltage and (c) current efficiency-luminance curves, (d) EL spectra. S47

48 S48

49 Figure S48. Characteristics of the OLEDs based on complex 6 in the structure of ITO/ HATCN (5 nm)/ NPB (40 nm)/ TCTA (10 nm)/ DIC-TRZ: x% complex 6 (12 nm)/ BPBiPA (50 nm)/ LiF (1 nm)/ Al (150 nm) at varying dopant concentrations. (a) Current density-voltage, (b) luminance-voltage and (c) current efficiency-luminance curves, (d) EL spectra. S49

50 S50

51 Figure S49. Characteristics of the OLEDs based on complex 7 in the structure of ITO/ HATCN (5 nm)/ NPB (40 nm)/ TCTA (10 nm)/ DIC-TRZ: x% complex 7 (12 nm)/ BPBiPA (50 nm)/ LiF (1 nm)/ Al (150 nm) at varying dopant concentrations. (a) Current density-voltage, (b) luminance-voltage and (c) current efficiency-luminance curves, (d) EL spectra. S51

52 S52

53 Figure S50. Characteristics of the OLEDs based on complex 8 in the structure of ITO/ HATCN (5 nm)/ NPB (40 nm)/ TCTA (10 nm)/ DIC-TRZ: x% complex 8 (12 nm)/ BPBiPA (50 nm)/ LiF (1 nm)/ Al (150 nm) at varying dopant concentrations. (a) Current density-voltage, (b) luminance-voltage and (c) current efficiency-luminance curves, (d) EL spectra. S53

54 S54

55 Figure S51. Characteristics of the OLEDs based on complex 9 in the structure of ITO/ HATCN (5 nm)/ NPB (40 nm)/ TCTA (10 nm)/ DIC-TRZ: x% complex 9 (12 nm)/ BPBiPA (50 nm)/ LiF (1 nm)/ Al (150 nm) at varying dopant concentrations. (a) Current density-voltage, (b) luminance-voltage and (c) current efficiency-luminance curves, (d) EL spectra. S55

56 S56

57 Figure S52. Characteristics of the OLEDs based on complex 10 in the structure of ITO/ HATCN (5 nm)/ NPB (40 nm)/ TCTA (10 nm)/ DIC-TRZ: x% complex 10 (12 nm)/ BPBiPA (50 nm)/ LiF (1 nm)/ Al (150 nm) at varying dopant concentrations. (a) Current density-voltage, (b) luminance-voltage and (c) current efficiency-luminance curves, (d) EL spectra. S57

58 S58

59 Table S1. Triplet excited states of the four coordinated iridium(iii) cations from quantum chemical calculations by TD-DFT. Cation Triplet State E a [ev] λ b [nm] Excitation c Nature [Ir(ppy)2(bpy)] + T HOMO LUMO (100%) dπ(ir)-π(ppy) π*(bpy) T HOMO-1 LUMO (100%) dπ(ir)-π(ppy) π*(bpy) [Ir(ppy)2(dtb-bpy)] + T HOMO LUMO (100%) dπ(ir)-π(ppy) π*(dtb-bpy) T HOMO LUMO+2 (77.3%) HOMO-1 LUMO+3 (16.1%) HOMO-2 LUMO+2 (6.6%) dπ(ir)-π(ppy) π*(ppy) dπ(ir)-π(ppy) π*(ppy) dπ(ir)-π(ppy) π*(ppy) [Ir(phq)2(dtb-bpy)] + T HOMO LUMO (93.1%) HOMO LUMO+2 (6.9%) dπ(ir)-π(phq) π*(dtb-bpy) dπ(ir)-π(phq) π*(phq) T HOMO LUMO+1 (77.5%) HOMO-1 LUMO+2 (16.7%) HOMO-2 LUMO+1 (5.8%) dπ(ir)-π(phq) π*(phq) dπ(ir)-π(phq) π*(phq) dπ(ir)-π(phq) π*(phq) [Ir(piq)2(dtb-bpy)] + T HOMO LUMO (56.5%) HOMO LUMO+1 (20.5%) HOMO-1 LUMO+2 (15.4%) HOMO-2 LUMO+1 (7.6%) dπ(ir)-π(piq) π*(dtb-bpy) dπ(ir)-π(piq) π*(piq) dπ(ir)-π(piq) π*(piq) dπ(ir)-π(piq) π*(piq) T HOMO LUMO (37.9%) HOMO LUMO+1 (28.0%) HOMO-1 LUMO+1 (11.8%) HOMO-1 LUMO+2 (10.3%) HOMO LUMO+2 (6.4%) HOMO-2 LUMO+1 (5.6%) dπ(ir)-π(piq) π*( dtb-bpy) dπ(ir)-π(piq) π*(piq) dπ(ir)-π(piq) π*(piq) dπ(ir)-π(piq) π*(piq) dπ(ir)-π(piq) π*(piq) dπ(ir)-π(piq) π*(piq) a Calculated excitation energy for the triplet excited states. b Calculated emission wavelength. c The percentage in the parenthesis denotes the contribution of each mono-electronic excitation. S59

60 Table S2. Detailed device characteristics of the vacuum-evaporated-deposited OLEDs based on complexes 3-6. x a [%] Von b [V] Max CE c [cd/a] CE c at 10 3 cd/m 2 [cd/a] CEc at 104 cd/m2 [cd/a] max EQEd [%] max PE e > (0.41, 0.55) > (0.41, 0.55) > (0.41, 0.55) > (0.42, 0.54) > (0.43, 0.54) > (0.44, 0.53) > (0.44, 0.53) > (0.44, 0.53) > (0.43, 0.54) > (0.43, 0.55) > (0.43, 0.55) > (0.43, 0.54) > (0.44, 0.54) > (0.45, 0.54) > (0.44, 0.53) > (0.44, 0.53) a x, dopant ratio. b Von, turn-on voltage (at the luminance of 1 cd/m 2 ). c CE, current efficiency. d EQE, external quantum efficiency. e PE, [lm/w] max L f [cd/m 2 ] λel g [nm] CIE h (x, y) power efficiency. f L, luminance. g λel, EL wavelength. h CIE, Commission Internationale de I'Elairage. S60

61 Table S3. Detailed device characteristics of the vacuum-evaporated-deposited OLEDs based on complexes x a [%] Von b [V] Max CE c [cd/a] CE c at 10 3 cd/m 2 [cd/a] CEc at 104 cd/m2 [cd/a] max EQEd [%] max PE e > , 586 (sh) (0.48, 0.51) > , 586 (sh) (0.48, 0.51) > , 586 (sh) (0.48, 0.51) > , 586 (sh) (0.48, 0.50) > , 586 (sh) (0.48, 0.51) > , 586 (sh) (0.48, 0.51) > , 586 (sh) (0.48, 0.51) > , 586 (sh) (0.48, 0.50) > (sh), 626 (0.60, 0.40) > (sh), 626 (0.60, 0.40) > (sh), 626 (0.60, 0.40) > (sh), 626 (0.60, 0.40) (sh), 622 (0.59, 0.40) (sh), 624 (0.59, 0.40) (sh), 624 (0.59, 0.40) (sh), 624 (0.59, 0.40) a x, dopant ratio. b Von, turn-on voltage (at the luminance of 1 cd/m 2 ). c CE, current efficiency. d EQE, external quantum efficiency. e PE, [lm/w] max L f [cd/m 2 ] λel g [nm] CIE h (x, y) power efficiency. f L, luminance. g λel, EL wavelength, sh denotes the shoulder peak. h CIE, Commission Internationale de I'Elairage. S61