Supporting Information Platinum Functionalized Random Copolymers for use in Solution Processible Efficient Near-White Organic Light Emitting Diodes †
†
‡
,†
‡
Paul T. Furuta, Lan Deng, Simona Garon, Mark E. Thompson, Jean M. J. Fréchet* †
Department of Chemistry, University of California Berkeley, California 94720-1460
‡
Department of Chemistry, University of Southern California Los Angeles, California 90089-0744.
General. Emission spectra (photoluminescence and electroluminescence) were recorded on PTI QuantaMasterTM Model C-60SE spectrofluorometer, equipped with a 928 PMT detector.
Film
thicknesses were determined with a Rudolph Technologies Ellipsometer by spin casting films onto silicon wafers.
OLED fabrication. Prior to device fabrication, ITO on glass substrates were patterned as 2mm wide stripes with a resistivity of 20 Ω/. The substrates were cleaned by sonication in soap solution, rinsed with deionized water, boiled in trichloroethylene, acetone and ethanol for 3–4 min in each solvent and dried with nitrogen. Finally, the substrates were treated with UV ozone for 10 min. A layer of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) was spin-coated
onto the
substrate at 8000 RPM and baked at 90°C for 45 minutes. Polymers 6a-6d dissolved in a chloroform solvent such that the total weight was 15mg of polymer per mL solvent. The resulting solutions were filtered prior to use. The solutions were spin cast at 2000 RPM for 40sec. The film thicknesses were determined to be in the approximate range of 1000-1200 Å by ellipsometry. A 150 Å thick layer of 2,9dimethyl-4,7-diphenyl-1,10-phenanthroline
(BCP)
and
a
250
Å
layer
of
aluminum-tris(8-
hydroxyquinolate) (AlQ3) were deposited sequentially by thermal evaporation from resistively heated tantalum boats onto the polymer coated substrate at a rate of 2.0Å/s. The base pressure at room temperature was 3–4x10-6 Torr. After organic film deposition, the chamber was vented and a shadow mask with a 2 mm wide stripe was put onto the substrate perpendicular to the ITO stripes. A cathode consisting of 10Å LiF followed by 1000Å of aluminum was deposited at a rate of 0.3–0.4 Å/s for LiF S1
and 3–4Å/s for aluminum. OLEDs were formed at the 2x2 mm squares where the ITO (anode) and Al (cathode) stripes intersected.
OLED measurements. The devices were tested in air within 2 hours of fabrication. Device currentvoltage and light intensity characteristics were measured using the LabVIEWTM program by National Instruments with a Keithley 2400 SourceMeter/2000 Multimeter coupled to a Newport 1835-C Optical Meter, equipped with a UV-818 Si photocathode. Only light emitting from the front face of the OLED was collected and used in subsequent efficiency calculations. Electroluminescence spectra were recorded on a PTI QuantaMasterTM Model C-60SE spectrofluorometer.
Polymer synthesis and characterization.
General. All reagents were used as received and without further purification, or were prepared according to literature procedure, unless otherwise noted. NMR spectra were recorded on a Bruker DRX-500 instrument with TMS or solvent carbon signal as the standards. Platinum analysis by Schwarzkopf Microanalytical Laboratories, Woodside, NY. Size exclusion chromatography was carried out on a Waters GPC 150-CV plus system (Milford, MA) with an attached M486 tunable absorbance detector (254 nm). Polystyrene standards (18) were used for calibration and the mobile phase was tetrahydrofuran (1 mL/min, 45 °C). A bank of four PL Gel columns (5 µm) from Polymer Laboratories (Amherst, MA) was used: 100 Å, 100 Å, 500 Å, and a Mixed C.
General polymerization. Monomers 2-4 and initiator 1 were added to a test tube with magnetic stirbar, freeze-thaw pumped 3x under Ar, and sealed. The mixture was heated to 125 °C for 5 hours. The polymer was dissolved in CH2Cl2, and precipitated into methanol, re-dissolved in CH2Cl2, and precipitated in hexanes. Molecular weight (Table 1) was calibrated from light scattering data from polymers 5a-5d.
S2
General Pt functionalization. Acac functionalized polymer was added to a solution of Pt dimer [Pt-2(4,6-difluorophenyl)pyridyl(µ-Cl)]2 (2x excess per acac group ) and Na2CO3 (~10x excess per acac group) in 50 : 50 2-ethoxyethanol : anisole (least amount of solvent to dissolve reactants), in a test tube, backfilled with Ar 3X, and sealed. The solution was heated to 75 °C for 5hrs. The cooled solution was diluted in CH2Cl2, filtered through celite, and rinsed with CH2Cl2. The solution was concentrated, precipitated into methanol, filtered, and rinsed with water. Pt complex quantification is based on 1H NMR (reduction of enol peak at ~δ 16.75 and the benzyl shifts at ~δ 3.38 due to the enol form, addition of 1H peak at ~δ 8.90 due to the phenylpyridine ligand) and Pt analysis of 6c, averaging 80% functionalization of available acac sites.
5a. Recovered yield, 91%: 1H NMR (CDCl3) δ 1.51-2.34 (m, 147H), 2.91 (m, 1.2H ArCH2CH, ketoform), 3.38 (m, 0.8H ArCH2CH, enol-form), 3.87 (m, 0.6H COCHCO, keto-form), 5.89-7.24(m, 212H ArH),7.30-7.65 (m, 29H ArH), 8.01 (m, 22H ArH), 16.75 (s, 0.3H COH enol-form).
5b. Recovered yield, 85%: 1H NMR (CDCl3) δ 1.51-2.34 (m, 89H), 2.91 (m, 1.41H ArCH2CH, ketoform), 3.38 (m, 0.85H ArCH2CH, enol-form), 3.87 (m, 0.65H COCHCO, keto-form), 5.89-7.24(m, 124H ArH), 7.30-7.65 (m, 19H ArH), 8.01 (m, 13H ArH), 16.75 (s, 0.31H COH enol-form).
5c. Recovered yield, 94%: 1H NMR (CDCl3) δ 1.51-2.34 (m, 43H), 2.91 (m, 1.33H ArCH2CH, ketoform), 3.38 (m, 0.90H ArCH2CH, enol-form), 3.87 (m, 0.69H COCHCO, keto-form), 5.89-7.24(m, 65H ArH), 7.30-7.65 (m, 10H ArH), 8.01 (m, 7H ArH), 16.75 (s, 0.33H COH enol-form).
5d. Recovered yield, 93%: 1H NMR (CDCl3) δ 1.51-2.34 (m, 85H), 2.91 (m, 1.42H ArCH2CH, ketoform), 3.38 (m, 0.87H ArCH2CH, enol-form), 3.87 (m, 0.67H COCHCO, keto-form), 5.89-7.24(m, 176H ArH), 7.30-7.65 (m, 4H ArH), 8.01 (m, 2H ArH), 16.75 (s, 0.35H COH enol-form).
S3
6a. Recovered yield, 91%: 1H NMR (CDCl3) δ 1.51-2.35 (m,144H), 3.56 (m, 2.1H ArCH2C), 5.897.24(m, 223H ArH), 7.30-7.65 (m, 30H ArH), 8.01 (m, 26H ArH) 8.88 (s, 1H ArH).
6b. Recovered yield, 90%: 1H NMR (CDCl3) δ 1.51-2.34 (m, 92H), 3.56 (m, 2.3H ArCH2C), 5.897.24(m, 120H ArH), 7.31-7.65 (m, 25H ArH), 8.01 (m, 20H ArH), 8.89 (s, 1H ArH).
6c. Recovered yield, 91%: 1H NMR (CDCl3) δ 1.51-2.34 (m, 46), 3.56 (m, 2.2H ArCH2C), 5.897.24(m, 81H ArH), 7.30-7.65 (m, 14H ArH), 8.01 (m, 12H ArH), 8.89 (m, 1H ArH). Anal. calcd. for 100% functionalization of Pt, 9.03% , found 7.32%.
6d. Recovered yield, 96%: 1H NMR (CDCl3) δ 1.51-2.35 (m, 89H), 3.56 (m, 2.2H ArCH2C), 5.897.24(m, 185H ArH), 7.30-7.65 (m, 6H ArH), 8.01 (m, 5H ArH), 8.89 (s, 1H ArH).
Table 1. Polymer 5a-5d.
Polymer
Molar ratio 2:3:4
Molar ratio monomer : 1
Mn1
Mw1
PDI
5a
10 : 1 : 10
100 : 1
23400
28300
1.21
5b
6:1:6
100 : 1
20500
24600
1.19
5c
3:1:3
110 : 1
25500
29500
1.18
5d
10 : 1 : 2
100 : 1
23500
27700
1.18
(1) GPC calibration based on light scattering data
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Al:LiF 1000Å
Alq3 250Å
BCP 150Å TPA:Pt2Fppy:Oxadiazole (m : n : o random) 1000Å
PEDOT 450Å ITO Figure S1. Structure of devices 6a-6d.
Quantum Efficiency, %
10
1
6a 6b 6c 6d
0.1
0.01
1E-3 0.01
0.1
1
2
10
Current Density, mA/cm
Figure S2. EQE% vs current density
S5
6a 6b 6c 6d
100
Brightness, Cd/m
2
1000
10 1 0.1
0.01
0
5
10
Voltage, V
15
Figure S3. Brightness vs voltage
Current Density, mA/cm
2
100
6a 6b 6c 6d
10 1 0.1 0.01 1E-3 1E-4 1E-5
0.1
1
10
Voltage, V Figure S4. IV curve
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