Supporting Information

Transcription

1 S-1 Supporting Information Thermally Activated Delayed Fluorescence Pendant Copolymers with Electron and Hole-Transporting Spacers Chensen Li, Yukun Wang, Dianming Sun, Huihui Li, Xiaoli Sun, Dongge Ma, Zhongjie Ren, * Shouke Yan * Beijing Advanced Innovation Center for Soft Matter Science and Engineering, State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 129, China. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry Chinese Academy of Sciences, Changchun 1322, China. University of Chinese Academy of Sciences, Beijing 139, China. Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 5164, China. renzj@mail.buct.edu.cn, skyan@mail.buct.edu.cn Contents Page Materials and Characterization Device fabrication and Characterization Supporting Figures S1-S1 Supporting Tables S1-S2 Synthetic Scheme and Procedures References S-1 S-2 S-2 S-3 S-3 S-8 S-9 S-1 S-11 S-12 S-12 S-14

2 S-2 Materials All reactants (Adamas-beta) were purchased from Adamas Reagent, Ltd without further purification and all solvents were supplied by Beijing Chemical Reagent Co., Ltd. Anhydrous and deoxygenated solvents were obtained by distillation over a sodium benzophenone complex. Characterization 1 H NMR spectra were recorded on a Bruker AV4 (4 MHz) spectrometer. Chemical shifts (δ) are given in parts per million (ppm) relative to tetramethylsilane (TMS; δ = ) as the internal reference. 1 H NMR spectra data are reported as chemical shift, relative integral, multiplicity (s = singlet, d = doublet, m = multiplet), coupling constant (J in Hz) and assignment. Elemental analyses of carbon, hydrogen, nitrogen and sulfur were performed on a Vario EL cube. UV/Vis absorption spectra were recorded on a Hitachi U-291 spectrophotometer. PL spectra were recorded on a Hitachi F-7 fluorescence spectrophotometer. The temperature dependence of transient PL decay curves in different THF/water mixture and PL spectra in vacuum/air were determined using a spectrometer (FLS98) from Edinburgh Instruments Limited. The fluorescence quantum yields of solid films were measured on FLS98 with an integrating sphere (φ = 15 mm). Phosphorescence, prompt fluorescence (PF), and delayed fluorescence (DF) spectra and decays were recorded using nanosecond gated luminescence and lifetime measurements (from 4 ps to 1 s) with either a high-energy pulsed Nd:YAG laser emitting at 355 nm (EKSPLA) or a N2 laser emitting at 337 nm. Emission was focused onto a spectrograph and detected on a sensitive gated iccd camera (Stanford Computer Optics) having sub-nanosecond resolution. PF/DF time-resolved measurements were performed by exponentially increasing the gate and delay times. Differential scanning calorimetry (DSC) was performed on a TA Q2 differential scanning

3 S-3 calorimeter at a heating rate of 1 C min -1 from 25 to 31 C under nitrogen atmosphere. The glass transition temperature (T g ) was determined from the second heating scan. Thermogravimetric analysis (TGA) was undertaken with a METTLER TOLEDO TGA/DSC 1/11SF instrument. The thermal stability of the samples under a nitrogen atmosphere was determined by measuring their weight loss while heating at a rate of 1 C min -1 from 25 to 8 C. Cyclic voltammetry (CV) was carried out in nitrogen-purged acetonitrile at room temperature with a CHI voltammetric analyser. Tetrabutylammonium hexafluorophosphate (TBAPF 6.1 M) was used as the supporting electrolyte. The conventional three-electrode configuration consists of a glassy carbon working electrode, a platinum wire auxiliary electrode, and an Ag/AgNO 3 pseudo-reference electrode with ferrocenium-ferrocene (Fc + /Fc) as the internal standard. Cyclic voltammograms were obtained at scan rate of 1 mv s -1. The onset potential was determined from the intersection of two tangents drawn at the rising and background current of the cyclic voltammogram. Gel permeation chromatography (GPC) analysis was carried out on a Waters system using polystyrene standards as molecular weight references and tetrahydrofuran (THF) as the eluent. Device Fabrication and Characterization The hole-injection material PEDOT:PSS (Al 483) and electron-transporting and hole-blocking material TmPyPB were obtained from commercial sources. ITO-coated glass with a sheet resistance of 1 Ω per square was used as the substrate. Before device fabrication, the ITO-coated glass substrate was precleaned and exposed to UV-ozone for 2 min. PEDOT:PSS was then spin-coated onto the clean ITO substrate as a hole-injection layer. Next a mixture of 1% polymer, 9% mcp in chlorobenzene was spin-coated (1 mg/ml; 15 rpm) to form a ca. 45 nm

4 S-4 thick emissive layer and then annealed at 8 C for 3 min to remove the residual solvent. Finally, a 4 nm thick electron-transporting layer of TmPyPB was vacuum deposited, and a cathode composed of a 1 nm thick layer of Liq and aluminum (1 nm) was sequentially deposited through shadow masking with a pressure of 1-6 Torr. The current density-voltage-luminance (J-V-L) characteristics of the devices were measured using a Keithley 24 Source meter and a Keithley 2 Source multimeter. The EL spectra were recorded using a JYSPEX CCD3 spectrometer. The EQE values were calculated from the luminance, current density, and electroluminescent spectrum according to previously reported methods. 1 All measurements were performed at room temperature under ambient conditions. Supporting Figures W (log M) POPT Time (min) W (log M) POPT Time (min) W (log M) Time (min) POPT-41 Figure S1. GPC spectra of PCzPT-x and POPT-x.

5 S-5 Figure S2. 1 H NMR spectra of PCzPT-x and POPT-x. Current (A) PhCz Ph 3 PO (a) Potential (V vs. Ag/Ag + ) Normalized Intensity (a.u.) (b) PhCz Ph 3 PO Figure S3. (a) Cyclic voltammograms of PhCz and Ph 3 PO in acetonitrile. (b) The phosphorescent spectra of PhCz and Ph 3 PO measured at 77 K. The triplet energy of PhCz and Ph 3 PO are 3.1 ev and 2.75 ev, respectively.

6 S-6 Figure S4. The HOMO 1 and LUMO+1 distributions obtained by density functional theory simulations forpczpt-19 (a) andpopt-25 (b) (a) Time (µs) 8 K 15 K 22 K 3 K τ d (µs) τ d :rel (%) 74.4 (b) K 15 K 22 K 3 K 25k 2k 15k 1k 5k Air Vacuum (c) τ 8 K M (d) d (µs) (e) Air (f) τ 15 K d :rel (%) Vacuum 22 K 8k 3 K k Time (µs) K 15 K 22 K 3 K 4k 2k Figure S5. Transient photoluminescence decay (excited at 34 nm) curves at 55 nm for PCzPT-1 (a) and PCzPT-43 (d) from 8-3 K. Excited state lifetimes and ratios for delayed emission of PCzPT-1 (b) and PCzPT-43 (e) were calculated by transient photoluminescence decay curves. PL spectra in thin film of PCzPT-1 (c) and PCzPT-43 (f) under air atmosphere and vacuum. The calculated emission ratio of DF is 25.3% in PCzPT-1 and 7.2% in PCzPT-43.

7 S (a) 8 K 15 K 22 K 3 K 1 τ d (µs) τ d :rel (%) (b) M 2.M 1.5M M 5k (c) Air Vacuum Time (µs) 8K 15K 22K 3K (d) 8 K 15 K 22 K 3 K 8 τ d (µs) τ d :rel (%) (e) M 2.5M 2.M 1.5M M 5k (f) Air Vacuum Time (µs) 8K 15K 22K 3K Figure S6. Transient photoluminescence decay (excited at 34 nm) curves at 55 nm for POPT-13 (a) and POPT-41(d) from 8-3 K. Excited state lifetimes and ratios for delayed emission of POPT-13 (b) and POPT-41(e) were calculated by transient photoluminescence decay curves. PL spectra in thin film of POPT-13 (c) and POPT-41(f) under air atmosphere and vacuum. The calculated emission ratio of DF is 42.6% in POPT-13 and 17.5% in POPT-41. PL Intensity (a.u.) PL Intensity (a.u.) µs 2.4 µs 3.3 µs 5.2 µs 7. µs 9.8 µs 12.6 µs 16.3 µs (d) µs 2.4 µs µs 5.2 µs µs µs 12.6 µs µs (a) µs 1.5 µs (b) 2.4 µs 2 (c) µs 5.2 µs 7. µs 3.3 µs 5.2 µs 7. µs 9.8 µs 9.8 µs µs µs µs 16.3 µs PL Intensity (a.u.) PL Intensity (a.u.) (e) 1.5 µs 2.4 µs 3.3 µs 5.2 µs 7. µs 9.8 µs 12.6 µs 16.3 µs PL Intensity (a.u.) PL Intensity (a.u.) (f) 1.5 µs 2.4 µs 3.3 µs 5.2 µs 7. µs 9.8 µs 12.6 µs 16.3 µs Figure S7. Time resolved fluorescence spectra of PCzPT-1 (a), PCzPT-19 (b), PCzPT-43 (c), POPT-13 (d), POPT-25 (e) and POPT-41 (f). These data were measured in pristine films at room temperature. At early times, the fluorescence emission of all these polymers peaks at approximate 545 nm and then shifts to shorter wavelengths, peaking at around 525 nm at 16.3 µs. All of spectra intensities show an obvious decrease over time, indicating a decay process of delayed fluorescence.

8 This behavior is probably due to underlying phosphorescence, which becomes increasingly important when the DF becomes weaker. S-8 Normalized Intensity (a.u.) Delayed PL EL PL (a) Normalized Intensity (a.u.) Delayed PL PL EL PL (b) Normalized Intensity (a.u.) Delayed PL EL PL (c) Normalized Intensity (a.u.) Delayed PL EL PL (d) Normalized Intensity (a.u.) Delayed PL EL PL (e) Normalized Intensity (a.u.) Delayed PL EL PL (f) Figure S8. Overlay plots of PL, delayed PL (1.5µs), and EL spectra of PCzPT-1 (a), PCzPT-19 (b), PCzPT-43 (c), POPT-13 (d), POPT-25 (e) and POPT-41 (f). The EL spectra show a slight redshift comparing with PL spectra for PCzPT-x and POPT-x, which may be caused by the formation of electroplex. For POPT-x, the blueshifted delayed PL comparing with PL can be found, which may probably assign to the underlying phosphorescence. Current Density (ma/cm 2 ) Current Efficiency (ma/cm 2 ) PCzPT-1 PCzPT-19 PCzPT Voltage (V) 4 POPT-13 POPT-25 3 POPT Voltage (V) Luminance (cd/m 2 ) Luminance (cd/m 2 ) Current Efficiency (cd/a) Current Efficiency (cd/a) (a) (b) (c) Current Density (ma/cm 2 ) (d) E-4 (e) E-5 (f) 8 1 Luminance (cd/m 2 ) Figure S9. Non-doped devices data: current density-voltage-luminance (J-V-L) curves of PCzPT-x (a) and POPT-x (d); Current and power efficiency versus luminance for PCzPT-x (b) and POPT-x (e); EQE versus luminance for PCzPT-x (c) and POPT-x (f); the insets in parts (c) Luminance (cd/m 2 ) EQE (%) Power Efficiency (lm/w) EQE (%) E-3 1E E Current Density (ma/cm 2 ) 1 Luminance (cd/m 2 )

9 S-9 and (f) are electroluminescent spectra at 1 cd/cm 2. Current Density (ma/cm 2 ) Hole-PCzPT-1 Hole-PCzPT-19 Hole-PCzPT-43 Hole-POPT-13 Hole-POPT-25 Hole-POPT-41 (a) Voltage (V) Current Density (ma/cm 2 ) Electron-PCzPT-1 Electron-PCzPT-19 Electron-PCzPT-43 Electron-POPT-13 Electron-POPT-25 Electron-POPT-41 (b) Voltage (V) Current Density (ma/cm 2 ) Hole-mCP/PCzPT-1 Hole-mCP/PCzPT-19 Hole-mCP/PCzPT-43 Hole-mCP/POPT-13 Hole-mCP/POPT-25 Hole-mCP/POPT-41 (c) Voltage (V) Current Density (ma/cm 2 ) Electron-mCP/PCzPT-1 Electron-mCP/PCzPT-19 Electron-mCP/PCzPT-43 Electron-mCP/POPT-13 Electron-mCP/POPT-25 Electron-mCP/POPT-41 (d) Voltage (V) Figure S1. J-V curves of the hole-only devices for PCzPT-x, POPT-x (a) and mcp/pczpt-x, mcp/popt-x (c) and electron-only devices for PCzPT-x, POPT-x (b) and mcp/pczpt-x, mcp/popt-x (d). Table S1. OLED Performance. V on a (V) L max b (cd/m 2 ) CE max c (cd/a) PE max d (lm/w) EQE max e (%) λ peak f (nm) PCzPT PCzPT PCzPT POPT POPT POPT a The voltage at 1 cd/m 2. b Maximum luminance. c Maximum current efficiency. d Maximum power

10 S-1 efficiency. e EQE at maximum. f EL emission peak at 1 cd/cm 2. Table S2. Photophysical data of doped films in mcp (1 wt%) of PCzPT-x and POPT-x. a PCzPT-1 PCzPT-19 PCzPT-43 POPT-13 POPT-25 POPT-41 Φ PL [%] τ prompt [ns] τ delayed [µs] f R delayed [%] Φ prompt [%] Φ delayed [%] k p [1 7 s -1 ] k d [1 4 s -1 ] Φ IC [%] Φ ISC [%] Φ RISC [%] k F [1 6 s -1 ] k IC [1 6 s -1 ] k ISC [1 7 s -1 ] k RISC [1 5 s -1 ] k FET [1 5 s -1 ] a Abbreviations: Φ PL = absolute photoluminescence quantum yield; τ prompt and τ delayed = lifetimes calculated from the prompt and delayed fluorescence decay, respectively; f = oscillator strength; R delayed = the ratio of delayed components; Φ prompt and Φ delayed = fluorescent and delayed components, respectively, determined from the total Φ PL and the proportion of the integrated area of each of the components in the transient spectra to the total integrated area; k p and k d = prompt and delayed fluorescence decay rate, respectively; Φ ISC = the intersystem crossing quantum yield; k F = fluorescence decay rate; k IC = internal conversion decay rate from S 1 to S ; k ISC = intersystem crossing decay rate from S 1 to T 1 ; k RISC = the rate constant of reverse intersystem crossing process; k FET = Förster energy transfer rate. The quantum efficiencies and rate constants were determined

11 S-11 using the following equations according to literatures (equations 1-7, 1 8 2, 9-1 3, 11 4 and 12 5 ) Φ prompt = Φ PL R prompt (1) Φ delayed = Φ PL R delayed (2) k F = Φ prompt /τ prompt (3) Φ PL = k F /(k F + k IC ) (4) Φ prompt = k F /(k F + k IC + k ISC ) (5) Φ IC = k IC /(k F + k IC + k ISC ) (6) Φ ISC = k ISC /(k F + k IC + k ISC ) = 1 Φ prompt Φ IC (7) Φ RISC = Φ delayed /Φ ISC (8) k RISC = (k p k d Φ delayed )/(k ISC Φ prompt ) = R delayed /(R prompt τ delayed ) (9) k p = 1/τ prompt ; k d = 1/τ delayed (1) f = 3/(2E 2 S1 τ delayed ) (11) τ prompt = 1/(k ISC + k F + k IC + k FET ) (12) Synthetic Scheme and Procedures Scheme S1. Synthetic routes to the monomers and copolymers.

12 S-12 2,8-Dibromo-dibenzothiophene (2) and 2,8-Dibromo-dibenzothiophene-S,S-dioxide (3) were prepared according to the reference. 6 2-Bromo-8-vinyldibenzothiophene-S,S-dioxide (4) and 2-(1H-Phenothiazin-1-yl)-8-vinyldibenzothiophene-S,S-dioxide (5) were prepared following the procedures in reference. 7 9-(4-vinylphenyl)-9H-carbazole (8): 8 Potassium carbonate (4.2 g, 3 mmol), copper iodide (2.85 g, 15 mmol), 1,1-phenanthroline (36 mg, 1.6 mmol), carbazole (2.5 g, 15 mmol), 1-bromo-4-vinylbenzene (1.81 g, 1 mmol), and dried N,N-dimethylformamide (4 ml) were added into a 1 ml flask under a nitrogen atmosphere. The mixture was stirred for 3 min at room temperature, and then heated to 12 C for 2 d until the reaction was complete (monitored by TLC). After cooling to room temperature, the resulting mixture was transferred into a 5 ml beaker and ice water (2 ml) was poured into the beaker under stirring. The suspension was filtered and the residue was washed with water. Afterwards, the residue was suspended in dichloromethane (1 ml) and the insoluble material was removed by filtration. The filtrate was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude product was purified by column chromatography on silica gel (petroleum ether) to produce a white solid of 2.8 g (76.9%). 1 H NMR (4 MHz, CDCl 3 ): δ 8.14 (d, J = 7.8 Hz, 2H), 7.64 (d, J = 8.4 Hz, 2H), 7.53 (d, J = 8.4 Hz, 2H), (m, 4H), (m, 2H), 6.83 (dd, J = 17.6, 1.9 Hz, 1H), 5.85 (d, J = 17.6 Hz, 1H), 5.36 (d, J = 1 Hz, 1H). 13 C NMR (1 MHz, CDCl 3 ) δ 141.1, 137.4, 137.1, 136.2, 127.8, 127.3, 126.1, 123.7, 12.5, 12.1, 114.9, 11. Diphenyl(4-vinylphenyl)phosphine oxide (11): 9 1-bromo-4-vinylbenzene (1.12 g, 6.2 mmol) was dissolved in 3 ml of anhydrous THF under Ar atmosphere and cooled to -78. n-butyllithium (1.3 equivalents, 1 M in hexanes, ml) was added dropwise to give a bright brown solution. Stirring was continued for 3 h at -78, and then chlorodiphenylphosphine (1.48 ml, 8.6 mmol) was added to give a clear, yellow solution. The reaction mixture was stirred for 3 h at -78 before quenching with degassed methanol (1 ml). Volatiles were removed under reduced pressure to give an off-white solid. It was digested in methanol, filtered, digested in water, and filtered. The crude material was purified by column chromatography. Diphenyl(4-vinylphenyl)phosphine (1 g, 2.3 mmol), methylene chloride (1 ml), and 3% hydrogen peroxide (2 ml) were stirred overnight at room temperature. The organic layer was

13 S-13 separated and washed with water and then brine. The extract was evaporated to dryness affording a white solid, which was further purified by column chromatography. Yield 95%. 1 H NMR (4 MHz, CDCl 3 ): δ (m, 6 H), (m, 2 H), (m, 6 H), 6.72 (dd, J = 17.6, 1.9 Hz, 1 H), 5.83 (d, J = 17.6 Hz, 1 H), 5.35 (d, J = 1.9 Hz, 1 H). 13 C NMR (1 MHz, CDCl 3 ): δ 141.1, 136., 132.7, 132.5, 132.1, 132., 131.7, 128.6, 126.3, References: [1] Zhang, Q.; Kuwabara, H.; Potscavage Jr, W. J.; Huang, S.; Hatae, Y.; Shibata, T.; Adachi, C. Anthraquinone-Based Intramolecular Charge-Transfer Compounds: Computational Molecular Design, Thermally Activated Delayed Fluorescence, and Highly Efficient Red Electroluminescence. J. Am. Chem. Soc. 214, 136, [2] Xie, G.; Li, X.; Chen, D.; Wang, Z.; Cai, X.; Chen, D.; Li, Y.; Liu, K.; Cao, Y.; Su, S. J. Evaporation- and Solution-Process-Feasible Highly Efficient Thianthrene-9,9',1,1'-Tetraoxide-Based Thermally Activated Delayed Fluorescence Emitters with Reduced Efficiency Roll-Off. Adv. Mater. 216, 28, [3] Uoyama, H.; Goushi, K.; Shizu, K.; Nomura, H.; Adachi, C. Highly Efficient Organic Light-Emitting Diodes from Delayed Fluorescence. Nature 212, 492, [4] Cao, Z.; Zhang, Q. Computational Analyses of Singlet-Singlet and Singlet-Triplet Transitions in Mononuclear Gold-Capped Carbon-Rich Conjugated Complexes. J. Comput. Chem. 25, 26, [5] Zhang, D.; Zhao, C.; Zhang, Y.; Song, X.; Wei, P.; Cai, M.; Duan, L. Highly Efficient Full-Color Thermally Activated Delayed Fluorescent Organic Light-Emitting Diodes: Extremely Low Efficiency Roll-Off Utilizing a Host with Small Singlet-Triplet Splitting. ACS Appl. Mater. Interfaces 217, 9,

14 S-14 [6] Liu, J.; Zou, J.; Yang, W.; Wu, H.; Li, C.; Zhang, B.; Peng, J.; Cao, Y. Highly Efficient and Spectrally Stable Blue-Light-Emitting Polyfluorenes Containing a Dibenzothiophene-S,S-dioxide Unit. Chem. Mater. 28, 2, [7] Nobuyasu, R. S.; Ren, Z.; Griffiths, G. C.; Batsanov, A. S.; Data, P.; Yan, S.; Monkman, A. P.; Bryce, M. R.; Dias, F. B. Rational Design of TADF Polymers Using a Donor-Acceptor Monomer with Enhanced TADF Efficiency Induced by the Energy Alignment of Charge Transfer and Local Triplet Excited States. Adv. Opt. Mater. 216, 4, [8] Pan, L.; Chen, Q.; Zhu, J.-H.; Yu, J.-G.; He, Y.-J.; Han, B.-H., Hypercrosslinked Porous Polycarbazoles via One-Step Oxidative Coupling Reaction and Friedel-Crafts Alkylation. Polym. Chem. 215, 6, [9] Jeon, S. O.; Yook, K. S.; Joo, C. W.; Lee, J. Y., Phenylcarbazole-Based Phosphine Oxide Host Materials for High Efficiency in Deep Blue Phosphorescent Organic Light-Emitting Diodes. Adv. Funct. Mater. 29, 19,