Supporting Information

Transcription

1 Supporting Information Electroluminescent Pressure Sensing Displays Seung Won Lee,, Sung Hwan Cho,, Han Sol Kang, Gwangmook Kim, Jong Sung Kim, Beomjin Jeong, Eui Hyuk Kim, Seunggun Yu, Ihn Hwang, Hyowon Han, Tae Hyun Park, Seok-Heon Jung, Jin Kyun Lee, Wooyoung Shim and Cheolmin Park, * Department of Materials Science and Engineering, Yonsei University Yonsei-ro 50, Seodaemun-gu, Seoul, (Republic of Korea) Department of Polymer Science and Engineering, Inha University Yonghyeon-dong, Nam-gu, Incheon, (Republic of Korea) Corresponding Author * address: cmpark@yonsei.ac.kr Office phone: Fax: S-1

2 S1. Fabrication process of an EPSD Figure S1. Fabrication processes of an EPSD consisting of six vertically stacked layers. (a) Schematic illustration of fabricating HIL/emissive layer/etl on an ITO on a substrate. (b) Schematic of fabricating a topographically patterned ionic gel layer with micropyramids on a HIL. S-2

3 S2. Atomic composition of an EPSD Figure S2. Chemical analysis of the constituent layers of an EPSD. (a) Two-dimensional mapping and (b) energy spectra of TEM-EDX measurement with multivariate statistical analysis of characteristic atomic elements of the constituent layers. (c) An original TEM image without color decoration. S-3

4 S3. Operation mechanism of an EPSD Figure S3. Light emission mechanism of an EPSD under pressure. Energy levels of the EPSD in (a) unloaded and (b and c) loaded states with forward bias and reverse bias, respectively. Effective impedance increase with enlarging contact area as decreasing air gap and (ii) increasing built-in field as decreasing thickness, making effective dielectric constant (ε eff ) increase. S-4

5 S4. Electrical characterization of an ionic gel Figure S4. Electrical analysis of an ionic gel. (a) Schematic of the ionic gel layer sandwiched between two electrodes (left) and its electrical circuit (right). (b) Impedance, (c) Capacitance, (d) Phase angle of the ionic gels with 3.5 and 14 µm thickness as a function of frequency. S-5

6 S5 S9. Light emitting performance of ACEL devices with flat ionic gel layers Figure S5. Frequency dependent EL performance of ACELs with flat ionic gel layers. (a) Luminance characteristics and (b) maximum luminance values of devices with flat ionic gel layers having various ionic liquid contents with respect to polymer at 14 V and 20 V, respectively. S-6

7 Figure S6. Capacitance of ACELs as a function of frequency. (a) Devices with flat ionic gel layers. (b) Devices with micropatterned ionic gel layers having different ionic liquid contents. S-7

8 Figure S7. L V characteristics of the devices with flat insulating layer having no ionic liquid as a function of the thickness. Threshold voltages of the devices as a function of the thickness of flat layer without ionic liquid from 200 nm to 14 µm are shown thickness dependency. S-8

9 Figure S8. Time-resolved EL signals of an ACEL with an ionic gel layer containing 25 wt% ionic liquid under AC voltage with frequency of 1 khz. S-9

10 Figure S9. EL efficiency and characteristics of ACELs with flat ionic gel layers having different ionic liquid contents. (a) Current density (ma cm 2 ), (b) current efficiency (cd A 1 ), (c) phase angle (θ) of the devices as a function of AC frequencies. S-10

11 S10. Capacitive and luminescent responses of the EPSD Figure S10. A combination plot of both capacitance and EL sensitivity as a function of pressure to enable complementary pressure sensing across scales. S-11

12 S11 S12. Reliability test of EPSD Figure S11. Capacitance changes of a set of 5 EPSDs for reproducibility test. S-12

13 Figure S12. Capacitance change of an EPSD for stability under high relative humidity. S-13

14 S13. The OM image of pyramids regions Figure S13. An OM image of an EPSD without AC field. S-14

15 S14 S15. Characterization for mechanical properties of soft materials Figure S14. Accurate calculation of contact area with hue, saturation, and value (HSV) scale analysis. (a) A photograph showing a mobile phone based application we made in our laboratory for facile image process. (b) Photographs converted by value scale from the images shown in figure 4d. (c) Pixel calculation images converted using MatLab image process from the images shown in Figure 6d. S-15

16 Figure S15. Slope calculation for characterising Young s modulus of an elastomer. A cubic of contact radius versus applied force with various PDMS:crosslinker mixing ratios. (a) 5:1, (b) 10:1, (c) 20:1, and (d) 30:1. S-16

17 Table S1. The characteristics of the visualization of pressure sensing light emitting display recently reported in the literature and the EPSD present in the current work. S-17