TFT-directed Electroplating of RGB Luminescent Films without a Vacuum or Mask towards a Full-colour AMOLED Pixel Matrix

Transcription

1 Supporting Information TFT-directed Electroplating of RGB Luminescent Films without a Vacuum or Mask towards a Full-colour AMOLED Pixel Matrix Rong Wang, ab Donglian Zhang, a You Xiong, a Xuehong Zhou, a Cao Liu, a Weifeng Chen, a Weijing Wu, a Lei Zhou, c Miao Xu, c Lei Wang, ac Linlin Liu, a * Junbiao Peng, a Yuguang Ma, ab * Yong Cao a a Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou , P. R. China. b State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun , P. R. China. c Guangzhou New Vision Opto-electronic Technology Co., Ltd. Guangzhou , P. R. China. msliull@scut.edu.cn; ygma@scut.edu.cn Table of the contents: 1. Experiment section... S-1 2. The structure of TFT... S-3 3. Output curves of the TFT... S-4 4. CV curves of RGB precursors deposited on the AMOLED backplane... S-4 5. AFM images of RGB EP films deposited on the AMOLED backplane... S-5 6. Electroluminescence photo of RGB devices with random arrangement on 6 5 pixel AMOLED backplane.... S-6

2 7. CV curves of EDOT deposited under various TFT conditions... S-6 8. Raman mapping images and Raman spectra of PEDOT films deposited under various TFT conditions... S-8 9. The pixel structure of display backplane and the boundary of pixel...s EP behavior of OCBzC and the quality of OCBzC EP films on smaller pixels...s References... S-11

3 1. Experiment section Materials Tetrabutylammonium hexafluorophosphate (TBAPF 6, 98%) was purchased from Alfa Aesar, recrystallized twice from ethanol and dried for 24 h under vacuum before being used. TCTA, TPBi (Alfa Aesar, packed under argon) and 3,4-ethoxylenedioxythiophene (EDOT) were used as received. All solvents were purchased from Sigma-Aldrich and used without further purification. The syntheses of OCNzC, OCBzC and OCPC have been previously reported by our group. 1,2 The thin-film transistors, pixel electrodes and AMOLED backplanes were provided by Guangzhou New Vision Opto-electric Technology Co., Ltd. Instrumentation The electrochemical polymerization was performed using a standard one-compartment, three-electrode electrochemical cell attached to a CHI 760D electrochemical workstation. The characteristic plots of the TFT were measured using an Agilent B1500A semiconductor parameter analyser. Tapping mode AFM images were taken in air using a Nanoscope III, Digital Instrument system equipped with a 0.01 mm 0.01 mm scanner and a silicon nitride cantilever. The electroluminescence spectra of EP films on pixel electrodes were obtained using a fibre optic spectrometer. Fluorescence microscopy photographs were obtained with a Leica DM4000 fluorescence microscope. Raman spectra and Raman mapping were recorded with a Renishaw invia Reflex Raman spectrometer with a 633 nm DPSS laser (maximum power 50 mw). For the Raman spectra and mapping measurement, an ocular S-1

4 objective of 10 and a long focal length objective of 50 with NA=0.5 were used. The sample was measured under 10% power, 1 s exposure and 8 accumulation, and the mapping step was 4 µm. The thickness of EP films was measured by a Bruker Dektak, and the thickness of other films was monitored by the Filtech during thermal evaporation. Electrochemical experiments & device fabrication CV experiments were performed using a standard one-compartment, three-electrode electrochemical cell. A Ag/Ag + nonaqueous electrode was used as the reference electrode. Bare ITO or an ITO coating with 1 nm thick AuNP pixels (200 µm 200 µm or 400 µm 400 µm) was used as the working electrode, and titanium metal was used as the counter electrode. AuNPs were deposited on the ITO by thermo-evaporation in a vacuum chamber with a base pressure of mbar and an evaporation rate of 0.05 Å s -1. A mixture of OCNzC, OCBzC or OCPC (0.5 mg ml 1 ) and TBAPF 6 (0.1 M) with CHCN 3 and CH 2 Cl 2 (V/V=2/3) was used as the electrolyte solution. A mixture of EDOT (2 mm) and TBAPF 6 (0.1 M) with CHCN 3 was used as the electrolyte solution. After the EP process, the resulting EP film was washed with solvents to remove any unreactive precursors and supporting electrolytes and then dried in a vacuum oven. For device fabrication, 35 nm TPBi, 1 nm CsF and 100 nm Al were deposited onto the EP film/au/ito surface by thermo-evaporation in a vacuum chamber with a base pressure of mbar. All device fabrication processes were conducted in a N 2 -filled glove box. S-2

5 2. The structure of TFT Figure S1. The structure of TFT. The TFT was fabricated with the following structure: Glass/Mo (200 nm)/sin X (250 nm)/sio X (50 nm)/ Ln-IZO (40 nm)/ SiO 2 (400 nm)/mo (200 nm) /DL 1000 (1500 nm), they were constructed as Figure S1. The Mo and Ln-IZO layers were prepared by physical vapor deposition and patterned by photolithography and wet etching. The insulating layer SiN X, SiO X, SiO2 and passivation layer DL1000 were prepared by chemical vapor deposition and patterned by photolithography and dry etching. S-3

6 3. Output curves of the TFT I ds (A) 5.0x x x x10-4 TFT: 100 µm/10 µm µ Vg=-5 V Vg=0 V Vg=5 V Vg=10 V Vg=15 V Vg=20 V 1.0x V ds (V) Figure S2. Output curve of the TFT with width/length of 100 µm/10 µm. 4. CV curves of RGB precursors deposited on the AMOLED backplane TFT: Vsel=10 V, Vdata=10 V, Vdd= V Red: OCNzC Current (a.u.) Green: OCBzC Blue: OCPC 0.1 µa Potential ( V vs Ag/Ag + ) Figure S3. CV curves of RGB precursors on the AMOLED backplane when TFT driving circuit worked at on state. S-4

7 5. AFM images of RGB EP films deposited on the AMOLED backplane Figure S4. AFM images of RGB EP films deposited on the AMOLED backplane when TFT driving circuit worked at on state. (a) OCNzC EP film, (b) OCNzC EP film, (c) OCPC film. S-5

8 6. Electroluminescence photo of RGB devices with random arrangement on 6 5 pixel AMOLED backplane. Figure S5. Electroluminescence photo of RGB devices with random arrangement on 6 5 pixel AMOLED backplane. Device structure: ITO/TCTA (10 nm)/ocnzc (55 nm) or OCBzC (65 nm) or OCPC (60 nm)/tpbi(35 nm)/csf(1 nm)/al(100 nm). Where TCTA is 4,4,4 -Tri(9-carbazoyl)triphenylamine, which is a typical hole transport material. 7. CV curves of EDOT deposited under various TFT conditions (a) 0.0 (b) 0.0 Current (1e-6 A) Vsel=13 V, Vdata=10 V, Vdd= V Potential (V vs Ag/Ag + ) Current (1e-6 A) Vsel=18 V, Vdata=15 V, Vdd= V Potential (V vs Ag/Ag + ) S-6

9 (c) 0.0 Current (1e-6 A) Vsel=23 V, Vdata=20 V, Vdd= V Potential (V vs Ag/Ag + ) (d) Current (1e-6 A) without TFT, Vdd= V Potential (V vs Ag/Ag + ) (e) Voltage (V) without TFT Vdata=10 V Vdata=15 V Vdata=20 V t (s) Figure S6. CV curves of EDOT deposited on pixel ITO electrodes (200 µm 200 µm) under various TFT conditions over the scanning voltage range of -0.3 to 1.06 V at a scanning rate of 50 mv s -1 for 6 scanning cycles of: (a) Vsel=13 V, Vdata=10 V; (b) Vsel=18 V, Vdata=15 V; (c) Vsel=23 V, Vdata=20 V; and (d) without using the TFT. (e) Scanning voltage curves for various TFT conditions. S-7

10 8. Raman mapping images and Raman spectra of PEDOT films deposited under various TFT conditions Figure S7. Raman mapping images of the peak intensity of 1425 cm -1 of PEDOT films deposited on pixel ITO electrodes (200 µm 200 µm) under various TFT conditions over the scanning voltage range of -0.3 to 1.06 V with scanning rate of 50 mv s -1 for 6 scanning cycles: (a) Vsel=13 V, Vdata=10 V; (b) Vsel=18 V, Vdata=15 V; (c) Vsel=23 V, Vdata=20 V; and (d) without using the TFT. (e) Raman spectra of PEDOT films deposited under various conditions. The output curves of the TFT indicate that at the same Vds, the Ids was different for different Vg. In this section, we chose EDOT, a classical electro-active precursor with a fast reaction rate, as the electro-active precursor; thus, the thickness of PEDOT is sensitive to the EP parameters. 3,4 We investigated the EP behaviour of EDOT for various gate voltages (Vdata=10 V, 15 V and 20 V; Vdata was equivalent to the Vg of T2) of T2 but an identical EP signal (Vdd=-0.3~1.06 V). The results shown in Figure S6 revealed that the CV curves were similar, but the current increased as Vdata S-8

11 increased, mainly due to the various voltage drops of the TFTs when exposed to various gate voltages, and larger Vdata corresponded to a smaller voltage drop, as shown in Figure S4.e. Therefore, the thickness of the PEDOT films increased with increasing Vdata (105 nm for Vdata=10 V, 135 nm for Vdata=15 V, 160 nm for Vdata=20 V and 185 nm without TFT), which was coincident with the variation in current. 5 Moreover, we used Raman mapping to provide further insight into the thickness and distribution of PEDOT films, as shown in Figure S7, to characterize PEDOT films with various thicknesses and demonstrated that the Raman signal is sensitive to the thickness. The Raman spectra of PEDOT films deposited under various conditions are shown in Figure S7.e. When mapping the intensity of the peaks at 1425 cm -1 for the PEDOT films deposited under various conditions, the distribution and thickness of PEDOT films can be clearly observed. The peak intensity at 1425 cm -1 increased with increased Vdata, but all values were lower than that of the film deposited without TFT, which was consistent with the results discussed above. S-9

12 9. The pixel structure of display backplane and the boundary of pixel Figure S8. (a) The pit structure of pixel on display backplane, (b) The AFM image and the cross section of the boundary of pixel of 200 µm 200 µm. A=pixel/Au/OCBzC, B= insulating layer. 10. EP behavior of OCBzC and the quality of OCBzC EP films on smaller pixels Figure S9. CV curves of OCBzC on ITO/AuNP pixel electrode (100 µm 100 µm) under various conditions (a) without using the TFT, (d) Vsel=10 V, Vdata=10 V; AFM S-10

13 images of OCBzC films deposited on the ITO/AuNP pixel electrode (100 µm 100 µm) under different conditions (b) without using the TFT, (e) Vsel=10 V, Vdata=10 V; fluorescence microscopic photos of OCBzC films deposited on the ITO/AuNP pixel electrode (100 µm 100 µm) under various TFT conditions (c) without using the TFT, (f) Vsel=10 V, Vdata=10 V. The first 10 cycles CV curves of OCBzC on ITO/AuNP pixel electrode of 100 µm 100 µm without or with TFT driving circuit were shown in Figure S8.a and d, which also exhibited very reversible redox reaction as on larger pixel electrodes, and there was only a very slight current decrease caused by the small voltage drop of the TFT. Very smooth morphology of OCBzC films deposited without or with TFT driving circuit were also witnessed by AFM (Figure S8.b and e) with Rms of 1.11 nm and nm, respectively. Additionally, uniform fluorescence of both OCBzC EP films were also observed by fluorescence microscope (Figure S8.c and f). These results demonstrated that TDDE method can be used to fabricate luminescent films on smaller pixels for more elaborate displays. 11. References (1) Lv, Y.; Yao, L.; Gu, C.; Xu, Y.; Zhang, Y.; Xie, Z.; Liu L.; Ma, Y. Cross-linked luminescent films via electropolymerization of multifunctional precursors for highly efficient electroluminescence. Polym. Chem. 2013, 4, (2) Yao, L.; Xue, S.; Wang, Q.; Dong, W.; Yang, W.; Wu, H.; Zhang, M.; Yang, B.; Ma, Y. RGB Small Molecules Based on a Bipolar Molecular Design for Highly Efficient Solution-Processed Single-layer OLEDs. Chem. Eur. J. 2012, 18, S-11

14 (3) Zhang, C.; Hu, C.; Wang, G.; Ouyang, M.; Ma, C. A novel multichromic copolymer via electrochemical copolymerization of (S)-1,1 -binaphthyl-2,2 -diyl bis(n-(6-hexanoic acid-1-yl) pyrrole) and 3,4-ethylenedioxythiophene. Electrochim. Acta 2010, 55, (4) Liu R.; Lee, S. B. MnO2/Poly(3,4-ethylenedioxythiophene) Coaxial Nanowires by One-Step Coelectrodeposition for Electrochemical Energy Storage. J. Am. Chem. Soc. 2008, 130, (5) Yu, T.; Ni, Z.; Du, C.; You, Y.; Wang, Y.; Shen, Z. Raman Mapping Investigation of Graphene on Transparent Flexible Substrate: The Strain Effect. J. Phys. Chem. C 2008, 112, S-12