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Investigation of photonic properties of self organized nanoparticles monolayers : application to photonic crystal cavities and patterned organic light.

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Presentation on theme: "Investigation of photonic properties of self organized nanoparticles monolayers : application to photonic crystal cavities and patterned organic light."— Presentation transcript:

1 Investigation of photonic properties of self organized nanoparticles monolayers : application to photonic crystal cavities and patterned organic light emitting diodes Getachew-T AYENEW Support de thèse : ANR OLD-TEA Direction de thèse : Alexis Fischer et Azzedine Boudrioua Encadrement : Mahmoud Chakaroun Assistance technologique Jeanne Solard Collaboration: Chii-Chang Chen ,National Central University , Taiwan PhD defence : July 8th, 2014 1

2 Outline Introduction Context State of the art Our approach Photonic properties of monolayer of opals and inverse-opals Numerical study of photonic band gaps Numerical study of microcavities Experimental approach of characterizing monolayer of opals Nanoparticle based 2D patterning of OLED 2D pattering of surfaces 2D patterning of OLEDs Conclusion and perspectives 2 2

3 Organic Laser Diode : A Threshold-Less Experimental Approach
1. Introduction Context :ANR OLD-TEA Organic Laser Diode : A Threshold-Less Experimental Approach Axe 1 Axe 2 1D Vertical confinement 2D lateral confinement Top down Bottom up High Q Small Mode volume Photonic Crystal Opals - Inverse Opals Extended cavity Poly(metmode volume hyl methacrylate) Potential Applications Low threshold organic diode laser 2D DFB lasers Light extraction in OLED 3 3 3

4 Objectives of the study
1. Introduction Objectives of the study Self-organized Nanoparticles Photonic crystals OLED Nanostructuration Photonic crystal laser with defect microcavity 2D-DFB OLD Light extraction in OLED Photonic properties of monolayer of nanoparticles and microcavities New patterning technique using nanoparticles 4 4

5 Objectives of the study
1. Introduction Objectives of the study Self-organized Nanoparticles Photonic crystals OLED Nanostructuration Photonic crystal laser with defect microcavity 2D-DFB OLD Light extraction in OLED Photonic properties of monolayer of nanoparticles and microcavities Making nanostructures using nanoparticles 5 5

6 2. Photonic properties of monolayer of opals and inverse-opals
State of the art Polymeric solid-state dye lasers resonator highly-efficient low threshold laser Emission spectra of the resonator cavity below and above lasing threshold Shi et al. Appl. Phys. Lett. 98, (2011) Dye doped photonic crystal Random lasing Kim et al Chem. Mater., 2009, 21 (20), pp 4993–4999 Murai et al, Chemistry LettersVol. 39 (2010) , No. 6 p.532 Lasing by randomly dispersing nanoparticles into a gain material multiple scattering porous photonic film enhanced stimulated emission 6 6

7 General objective/Methodology
2. Photonic properties of monolayer of opals and inverse-opals General objective/Methodology General objective Optimal design of planar photonic crystal using nanoparticles ? Microcavity ? Methodology Investigate numerically photonic band gaps in monolayer of dielectric spheres Investigate numerically quality factors of microcavities Experimental investigation of in-Plane propagation glass 7 7

8 2. Numerical study of photonic band gaps
Structures a air air a 2r 2.1 Numerical studies r r air air Opal without substrate Inverse opal without substrate a = period r = radius air air Introduction glass glass Opal with substrate Inverse opal with substrate 8 8 8

9 2. Numerical study of photonic band gaps
Rafractive index (n) for compact arrangement(r/a=0.5) 2. Numerical study of photonic band gaps Control parameters Refractive index (n) n of spheres in opals n of infiltrated material in inverse-opals Compactness of spheres , r/a ratio ( for n = 2.5, anatase TiO2) r/a=0.5, compact spheres r/a < 0.5 non- compact spheres r/a ratio determines the filling factor (ff) Filling factor Effective refractive index 9 9 9

10 2. Numerical study of photonic band gaps
Rafractive index (n) for compact arrangement(r/a=0.5) 2. Numerical study of photonic band gaps Parameters M K Direction of propagation of the incident field with respect to the crystal M ( TE, TM polarisations) ( TE, TM polarisations) K 10 10 10

11 2.1 Introduction to simulation
2. Numerical study of photonic band gaps 2.1 Introduction to simulation Simulation condition 3D finite-difference time-domain(3D-FDTD) method Boundary conditions Perfectly matched layer (PML) Periodic Cross section Top view 11 11

12 Photonic band gap(PBG) and construction of gap maps
2. Numerical study of photonic band gaps Photonic band gap(PBG) and construction of gap maps Photonic band gap Gap maps Photonic gapmap n=3 Transmission spectra PBG n=2.2 n=2.1 PBG n=1.5 M direction , TE polarization  direction , TE polarization (intersection) complete bandgap 12 12

13 Photonic band gap(PBG) and construction of gap maps
2. Numerical study of photonic band gaps Photonic band gap(PBG) and construction of gap maps Gap maps Different polarizations TE TM Different directions of propagation M K 13 13

14 Inverse opals without substrate
2. Numerical study of photonic band gaps Inverse opals without substrate r/a=0.5 n=2.5 Region for TE polarization TiO2(n=2.5) r/a PBG PBG exists for a wide range of refractive indices PBG exists for a wide range of compactnesses For n=2.5, Largest gap to mid-gap ratio for r/a=0.4, (TE) Δf f width of PBG = gap-mid-gap ratio= Δf/f 14 14

15 Opals without substrate
2. Numerical study of photonic band gaps Opals without substrate n=2.5, TiO2 Opals without substrate exhibit PBGs for different compactness 15 15

16 2. Numerical study of photonic band gaps
Opal or inverse opal ? гM-TE гM-TE First conclusion- monolayer of inverse opal offers larger gap-to-midgap ratio 16 16

17 Substrate effect: inverse-opal
2. Numerical study of photonic band gaps Substrate effect: inverse-opal r/a=0.5 TiO2(n=2.5) r/a TiO2(n=2.5) Losses to glass substrate No PBG for low ref. index materials Higher refractive index materials required PBG observed with non-compact spheres Overlap of TE mode for non- compact spheres 17 17

18 Substrate effect : opal
2. Numerical study of photonic band gaps Substrate effect : opal n=2.5 glass Lossy region Losses to glass substrate as r/a is lower More compact spheres favorable 18 18

19 Substrate effect : effect of compactness on losses
2. Numerical study of photonic band gaps Substrate effect : effect of compactness on losses larger filling factor More losses compact low neff compact high neff n=2.5 n=2.5 More compact non-compact low neff non-compact high neff Less compact More losses smaller filling factor Opals: as the spheres are more compact neff increases  less loss Inverse opals: as the spheres are more compact neff decreases  more loss 19 PBG observed when using non- compact spheres 19

20 Substrate effect : effect of compactness on losses
2. Numerical study of photonic band gaps Substrate effect : effect of compactness on losses Compact high neff More losses compact low neff Non compact low neff Non compact high neff More losses 20 PBG observed when using non- compact spheres 20

21 2. Numerical study of photonic band gaps
Conclusion Conclusion Structures without substrate exhibit PBGs for wide range of refractive indices and compactness Generally inverse opals have larger photonic bandgap width Structures with substrate have losses for lower refractive index materials Considering n=2.5, lower compactness in inverse opals and higher compactness in opals result in lower losses to glass substrate Inverse-opal with lower compactness on glass substrate seems to be a good compromise between the losses and the width of PBG Thus microcavities designed in non-compact sphere inverse-opals are expected to have better confinement Calculation of quality factors is necessary to optimize the optimum r/a value for a given refractive index 21 21

22 General objective/Methodology
2. Photonic properties of monolayer of opals and inverse-opals General objective/Methodology General objective Optimal design of planar photonic crystal using nanoparticles ? Microcavity ? Methodology Investigate numerically photonic band gaps in monolayer of dielectric spheres Investigate numerically quality factors of microcavities Experimental investigation of in-Plane propagation glass 22 22

23 2. Numerical study of microcavities
Fixed refractive index n= 2.5 Defects in the periodicity monitor source Investigation with respect to Various cavity geometries The r/a ratio with and without substrate (effect of the losses) The Quality factor investigated with respect to: with respect to the r/a ratio the cavity type H1 H2 L3 L5 23 23 23

24 Microcavities in inverse-opals
2. Numerical study of microcavities Microcavities in inverse-opals Cavity resonance in the PBG Significant resonant peaks observed for non-compact arrangement 24 24

25 Microcavities in inverse-opals
2. Numerical study of microcavities Microcavities in inverse-opals Quality factor optimized when r/a < 0.40 The presence of glass substrate reduces the quality factor The maximum of the Q-factor is obtained for 0.3 < r/a < 0.35 25 25

26 Microcavities in opals
2. Numerical study of microcavities Microcavities in opals H2 Higher refractive index of dielectric spheres needed in opals to have a resonance With the presence of glass substrate, the refractive index of the spheres needed is not feasible with available materials n=4 n=3.2 n=3.2 Higher refractive index values needed in opals to achieve a resonance: (n~4 realistic?) The inverse-opal arrangement is more favorable for microcavities 26 26

27 Conclusion on Microcavities
2. Numerical study of microcavities Conclusion on Microcavities Highest Q-factor(~300) obtained for non-compact spheres in inverse-opals. With a glass substrate the Q factor is limited to Q~200 Glass substrate reduces Q-factors Micro-cavities in opals require refractive index larger than n=3.2 which is hardly feasible The literature presents much higher Q-factor in conventional Phc Slabs. 27 27

28 General objective/Methodology
2. Photonic properties of monolayer of opals and inverse-opals General objective/Methodology General objective Optimal design of planar photonic crystal using nanoparticles ? Microcavity ? Methodology Investigate numerically photonic band gaps in monolayer of dielectric spheres Investigate numerically quality factors of microcavities Experimental investigation of in-Plane propagation glass 28 28

29 2. Towards experimental study of in-plane propagation in opal monolayers
Problem and method Objectives Measure of the In-Plane transmission spectra as a function of Polarization (TE, TM) Crystal direction (M, K) Problem Arrangement of spheres – presence of multiple domains Several directions are probed at the same time Method Fabrication of a single domain monolayers ? Characterization of single domain ? transmitted Direction of propagation transmitted 29 29 In plane transmission spectra characterisation of Monolayer dielectric spheres in optical regime Problems Many crystal domains in self assembled monolayer of spheres Nanoparticles too small to be manipulated

30 Approach: single domain samples and characterization
2. Towards experimental study of in-plane propagation in opal monolayers Approach: single domain samples and characterization Light ΓM ΓK Reference waveguide nanoparticles micro- hexagon Single domain fabrication Fabrication of micro-hexagons Micro-hexagon to force nanoparticles in ordered manner Dimension calculated for given nanoparticle diameter Single domain characterization Waveguides Polymer waveguide on a glass substrate In- and out-coupling Single domain probing 30 30

31 Preliminary experimental results: Fabricated waveguides
2. Towards experimental study of in-plane propagation of opal monolayers Preliminary experimental results: Fabricated waveguides 10µm micro-hexagon waveguide Clearly defined waveguide structure and micro-hexagon Different orientation of the micro-hexagons 31 31

32 Preliminary experimental results: Deposition of nanoparticles
2. Towards experimental study of in-plane propagation of opal monolayers Preliminary experimental results: Deposition of nanoparticles Micro-needle and micro-syringe sample 32 32

33 Preliminary experimental results: Deposition of nanoparticles
2. Towards experimental study of in-plane propagation of opal monolayers Preliminary experimental results: Deposition of nanoparticles 1.5µm spheres used for optimization of the process The diameter of the microneedle is too large as compared to the size of the micro-hexagon Nanoparticles not in the target area  33 33

34 Conclusion and perspectives
2. Towards experimental study of in-plane propagation of opal monolayers Conclusion and perspectives Conclusion Method of micro-hexagon promising to make single-domain monolayers Waveguides can enable in- and out- coupling from the nanoparticles Deposition by micro-needles not successful Perspective Deposition by microfluidic channels – easy to deliver the nanoparticle solution to micro-hexagon Adv. Funct. Mater., Vol. 19, 1247–1253(2009) 34 34

35 Conclusion and perspectives on opals and inverse-opals
2. Photonic properties of monolayer of opals and inverse-opals Conclusion and perspectives on opals and inverse-opals Numerical investigation on opals and Inverse opals Photonics bandgap exist in Opals and Inverse-Opals The inverse-opal structure exhibits larger PBG than the opal structure Non-compact inverse-opal structure has highest Q-factor Opal micro-cavities require high refractive index to have cavity resonances Experimental study of propagation in opals In-plane propagation experiment of single domain opals Micro-hexagons Waveguide Perspectives : Simulation: Mode volume calculation Experiment: nanoparticle self-organization by micro-channels 35 35

36 Objectives of the study
3. OLED Nanostruturation Objectives of the study Self-organized Nanoparticles Photonic crystals OLED Nanostructuration Photonic crystal laser with defect microcavity 2D-DFB OLD Light extraction in OLED Photonic properties of monolayer of nanoparticles and microcavities Making nanostructures using nanoparticles 36 36

37 Objectives of the study
3. OLED Nanostruturation Objectives of the study Objectives Patterning OLEDs Light extraction : requires period of lattice ~1-2.5 µm. 2D DFB laser : requires period of lattice < 500 nm. Issues E-beam Time consuming Expensive Method Principle of photolithography using nanoparticles Simulations Experiments Analysis (Journal of Nanoscience, Volume 2014 (2014)) 37 37

38 State of the art: Microsphere based lithography
3. 2D nanostructuration of OLED State of the art: Microsphere based lithography Laser exposure Optical Engineering 491, Nanoscale Res Lett., Vol. 3, 123–127(2008) Laser ablation (thermal removal) Micro-lens focusing 38 microsphere deposited every time patterning is made 38

39 State of the art: 2D patterning of OLEDs
3. 2D nanostructuration of OLED State of the art: 2D patterning of OLEDs Nano Letters, 2002, 2 (4), pp 333–335 OPTICS EXPRESS / 2005 / Vol. 13, No. 5 Electron-beam lithography Nanosphere lithography 39 39

40 Our approach : self-organized nanoparticle photolithography
3. 2D nanostructuration of OLED Our approach : self-organized nanoparticle photolithography UV Nanoparticle based reusable photolithographic mask Photomask made with nanoparticles Light exposure Development and reproducing close-packed microsphere pattern on photoresist Process advantages Reusable mask Simple Cheap Large area Monolayer of nanoparticles development patterned photoresist to OLED processing patterned OLED 40 40

41 Experiment : The process
3. 2D nanostructuration of OLED Experiment : The process Materials used Size and type of microspheres: SiO2- 800nm, 1µm, 1.25µm, 1.53µm, 1.68µm, 1.96µm, 2.34µm Polystyrene- 1.68µm Photoresist, Az-1505 Developer- MF-319 Process parameters Spin coating: 6000rpm Soft 90 sec. UV 0.9sec Developmenet: 9 sec 41 41

42 Results: Microsphere mask
3. 2D nanostructuration of OLED Results: Microsphere mask 2.5cm 1.7cm Large area microsphere thin-film on the substrate SEM: Periodically arranged monolayer of spheres - sometimes multiple domains in the crystal 42 42

43 3. 2D nanostructuration of OLED
Result: Patterned photoresist Homogenous pattern made by microsphere based photolithography Made by 2.34 µmsize microspheres microspheres mask 1µm 43 43

44 Results: 2 kinds of patterns on the same sample!
3. 2D nanostructuration of OLED Results: 2 kinds of patterns on the same sample! On the same sample the period of the monolayer mask reproduced UV half of the period of the monolayer mask 44 Periodically arranged monolayer of spheres - sometimes multiple domains in the crystal 44

45 3. 2D nanostructuration of OLED
Simulation: 2 kinds of patterns Micro-ball Lens effect Phase-mask effect period of pattern = period of microspheres period of pattern = ½ * (period of microspheres) Hard-contact and soft-contact modes of the mask aligner 45 45

46 Results: Different size of microsphere mask
3. 2D nanostructuration of OLED Results: Different size of microsphere mask Different size of microspheres: 800nm, 1µm, 1.25µm, 1.53µm, 1.68µm, 1.96µm, 2.34µm Two contact modes of the mask aligner: hard contact and soft contact Period of lattice less than 750nm hole diameter less than 405 nm Reduced-Period not observed for microsphere sizes of 800nm and 1μm 46 Periodically arranged monolayer of spheres - sometimes multiple domains in the crystal 46

47 3. 2D nanostructuration of OLED
Analysis Phase mask properties Transmitted angle Micro ball-lens focal length Numerical aperture 47 47

48 Micro-OLEDs: Structure
3. 2D nanostructuration of OLED Micro-OLEDs: Structure Green OLED patterned photoresist ITO glass Red OLED 48 48

49 3. 2D nanostructuration of OLED
Micro-OLEDs: Images Micro-OLED sizes = 1.27µm Method compatible with OLED operation 49 49

50 3. 2D nanostructuration of OLED
Micro-OLEDs: Spectra Perpendicular emission Small spectral modification of emitted light as compared to large area OLED Perspectives Measurements for other angles of emission Edge emission Smaller period of pattern glass 50 50

51 Conclusion and perspective
3. 2D nanostructuration of OLED Conclusion and perspective Conclusion Cheap, simple method to pattern 2D surfaces on large area The patterning method is compatible with OLED deposition Perspective Characterization of the emission Measurement of the emission diagram Edge emission Towards 2D-DFB laser : Smaller lattices : nm Lower exposure wavelength (<405nm) to increase the resolution of the nanoparticles lithography process Deep UV (DUV) lithography and DUV photoresist Use negative photoresist to make periodic pattern of micro nano-pillars 51 51 51

52 Conclusion and perspectives
3. 2D nanostructuration of OLED Conclusion and perspectives Etching ITO Deep UV litho. Smaller lattice (<500 nm) DFB lasing DFB lasing Etching glass substrate Etching glass substrate Light extraction (lattice ~ µm) Light extraction 52 52

53 4. General Conclusion Photonic properties of opal and inverse-opal monolayers Monolayers of O and I-O do exhibit photonic bandgap The inverse-opal structure exhibits larger PBG Using TiO2 ( n=2.5) the optimum structure with highest Q-factor is obtained in inverse –opals for r/a ratio ~ 0.32. Opal micro-cavities require high refractive index to have cavity resonances Perspectives: Non-compact (r/a=0.4) TiO2 inverse-opals would exhibit the largest PBG Nanoparticle photolithography Monolayers of nanoparticles used to make periodic pattern on photoresist Lattice down to 750 nm Holes down to 450 nm Array of micro-OLEDs (size = 1.27µm) fabricated Perspectives : 2D-DFB organic laser fabrication requires Deep-UV photolithography (193 nm) Applications of nanoparticles photolithography technique : Patterning surface with metal (SERS, Molecules detection, OLED efficiency increases via Surface Enhanced Plasmon Resonance. 53 53 53

54 Thank you for your attention
54 54

55 Conferences and papers
Getachew T. Ayenew, Alexis P.A. Fischer, Chia-Hua Chan, Chii-Chang Chen, Mahmoud Chakaroun, Jeanne Solard, Azzedine Boudrioua,”Two-dimensional patterning of organic light emitting diode based on self-organized nanoparticles photolithography” Submitted to optics Express (may 2014) F. Gourdon, A.P.A. Fischer, M. Chakaroun, G. Ayenew and Azzedine Boudrioua “Study of the organic layer thickness effect in a hybrid photonic crystal L3 nanocavity under optical pumping”, Accepted in Journal of Nanophotonics, 5 may 2014 Min Won Lee, Siegfried Chicot, Chii-Chang Chen, Mahmoud Chakaroun, Getachew Ayenew, Alexis Fischer, and Azzedine Boudrioua, Study of the Light Coupling Efficiency of OLEDs Using a Nanostructured Glass Substrate , Journal of Nanoscience, Volume 2014 (2014) Getachew T. Ayenew ; Mahmoud Chakaroun ; Nathalie Fabre ; Jean Solard ; Alexis Fischer ; Chii-Chang Chen ; Azzedine Boudrioua ; Chia-Hua Chan Photonic properties of two-dimensional photonic crystals based on monolayer of dielectric microspheres , Proc. SPIE 8424, Nanophotonics IV, 84242X (April 30, 2012); Sokha Khiev, Lionel Derue, Getachew Ayenew, Hussein Medlej, Ross Brown, Laurent Rubatat, Roger C. Hiorns, Guillaume Wantz and Christine Dagron-Lartigau,"Enhanced thermal stability of organic solar cells byusing photolinkable end-capped polythiophenes", Polym. Chem., 2013,volume 4, (2013) Conference Getachew T. Ayenew, Mahmoud Chakaroun, Nathalie Fabre, Jeanne Solard, Alexis Fischer, Azzedine Boudrioua, Chii-Chang Chen, Chia-Hua Chan, « Photonic properties of two-dimensional photonic crystals based on monolayer of dielectric nanospheres » Poster SPIE April 2012, Square Brussels Meeting Centre Brussels, Belgium. Getachew T. Ayenew, Anthony Coens, Mahmoud Chakaroun, Jean Solard, Alexis P. A. Fischer, Chii-Chang Chen, Chia-Hua Chan, Azzedine Boudrioua, Micro-Oled fabricated by microsphere based lithography, Optique Paris 13, 8 au 11 juillet 2013, Villetaneuse, Présentation Orale. Getachew T. Ayenew, Anthony Coens, Mahmoud Chakaroun, Jeanne Solard, Alexis P. A. Fischer, Chii-Chang Chen, Chia-Hua Chan, Azzedine Boudrioua, Micro-OLED fabricated by microsphere based photolithography, JNRDM 2013, Journées National du Réseau Doctoral en Micro-Nanotechnologies, juin 2013, Minatec Phelma, Grenoble, Poster 55 55 55

56 Analyse du problème de l'émission lumineuse
La structure OLED Interfaces ITO / Verre Verre /air Impact sur l'extraction lumineuse Réflexions aux interfaces : 0,8%<R ITO/Verre <19% R Verre/air  4% Angles limites : lim = Arcsin(n2/n1) Réflexion totale interne (TIR) Modes guidés dans le verre : 30% Modes guidées dans l'ITO : 50% Taux de couplage : 15 à 20 % Aluminium Organique n=1,7 ITO 50 à 30% n=1,8 à 2,2 lim TIR Verre Modes guidés 2 n=1,5 lim 30 à 50% 1 TIR Modes guidés 2 Lumière extraite 15% à 20% 56

57 Impact des angles limites
A partir de la loi de Descartes n2sin() = n1sin() Angles limites : lim = Arcsin(n2/n1) ITO/verre : 43°lim<56° Verre/Air : lim  42° ITO/air : 27°lim<33° (limpour n=2 Au delà de l'angle limite il y a réflexion totale interne (TIR) (onde guidée) Taux de couplage Ce qui est transmis : T( r2 sind T( transmittance en fonction de l'angle Couplage externe ITO/Air : 15 % Transmission au delà des angles limites? Modification de la géométrie grâce aux nanoparticules ? lim=56° Cône d'émission ITO /verre lim=42° Cône d'émission verre/air lim=30° Cône d'émission ITO/air 57

58 Organic compounds for OLED
Standard chemical products Alq3; tris(8-hydroxyquinolinato)aluminum; copper phthalocyanines N,N’-Di(naphthalen-1-yl)-N,N’-diphenyl-benzidine 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline/Bathocuproine 4,4'-Bis(2,2-diphenylvinyl)-1,1'-biphenyl 58 58

59 Organic semiconductors
Photonique Organique

60 DFB lasing Photonique Organique

61 DFB lasing Photonique Organique

62 Q-factor , mode volume Photonique Organique

63 Finite difference Photonique Organique


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