Self-assembly-sides 1_RFS

Kaushik Balakrishnan, PhD

Research Summary

1 [email protected]

Dimension and size control self-assembly of functional organic building blocks: New possibilities in organic

materials and device technologies

“0 D” “1 D” “2 D” “3 D”

FROM MOLECULES TO MATERIALS • Synthesis: π-rich molecules (PDI, and BTDs) and macrocycles • Self-assembly: Size and Dimension control • Applications: Sensing, Optical, Energy and Display


Research Summary

2 [email protected]

Self-Assembly• Spontaneous organization of a component (building blocks) into

ordered structures using interactions (non-covalent, ionic, etc.) inherent of the component(s) in select environment (solvent, vapor, surface, etc.).

• The self-assembled structures possess unique properties (new function) specific to the nature of organization of the building blocks and are often distinctly different from those of the individual building blocks.

• The collective organization of the building blocks therefore allow for realizing structures larger than themselves - bottom-up construction tool.

• Ability to control dimension (0D, 1D, 2D, and 3D) and size of resulting structures.

Examples of self-assembly DNA structure, formation of crystals, etc.

100#nm#1#nm# 10#nm# 1#µm#1#Å#

Size of building blocks (e.g., molecules, polymers

To#exploit#this#concept#for#material#science,#it#is#important#to#understand#the#interac5ons#between#the#building#blocks.

Different#noncovalent# interac5ons#between#the#molecules#play# significant# roles#during# the# self@assembly#@#enabling#size#and#shape#control.#

Principles of Self-assembly• Like prefers like • Governed by energetically favorable interactions


Research Summary

3 [email protected]

Self-Assembly of Functional Organic MoleculesImportance#of#Self@Assembled#Organic#Materials#• Broad'structural#diversity'in'terms'of'available'π@rich'molecules,'polymers,'oligomers'

• Ability'to'func9onalize'–'tailor#structural#and#electronic#characteris5cs'• Low'manufacturing'cost;'Suitable'for'large#area#applica9ons''• Fabrica9on'on'flexible#substrates'A'low'temperatures'of'deposi9on'A'solu5on#processing'• Device'performance'of'organic#devices#now#compe5ng'with'exis9ng'advance'materials'

• Good'Chromophores'A''High#absorp5vi5es'–'OptoAelectronic'applica9ons'• Fluorophores' with' high# quantum# yields' and' tunability# in# light# emission' depending' on'

func9onaliza9on'A' large'structural'diversity'to'allow' light'absorp9on'and'emission'over'broad#range#of#wavelengths#ranging#from'UV'to'Visible'to'InfraAred'

• Aggrega5on# Induced# Emission' (AIE)' in' designed' building' blocks' leads' to' new' opportuni9es' in'optoAelectronics,'photonics,'and'display'applica9ons'

• SelfAassembled' structures' with' varying' size’s' and' shapes' will' allow' both# fundamental#understanding' of' proper9es' associated'with' such' structures' and' enable'new#applica5ons' in'advance'op9cal,'and'photonics'devices

Optical

Electrical

Mechanical

Thermal

Novel&nano)scale&devices&

Dimension#and Size#Control

Tailor# Proper5es


Research Summary

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Self-Assembly of PTCDI*PTCDI’s#exhibit#unusual#proper5es#like#•#High'absorbi9viy'and'fluorescence'yields''•'Thermal,'chemical'and'photochemical'stability'

•'Solvatochromism'strongly'observed'in'these'dyes''

•'Strong'tendency'to'aggregate'via'πAstacking'between'the'perylene'units'•'nAtype'semiconductor'characteris9cs'as'compared'to'more'common'pAtype'

•'Synthe9c'advances'allow'func9onaliza9on'of'such'molecules'at'both'imide'nodes'(NAposi9ons)'and'

also'at'each'of'the'8Abay'func9onaliza9onA'leading'to'structural'diversity'A'structurally'these'dyes'

can'be'rigid#planar'to'unusually#twisted##•'Func9onaliza9on'also'influences'the'solubility

*PTCDI = 3,4,9,10-Perylene Tetracarboxylic Diimide

N N

O O

OO

R R

Chemical Structure of PTCDI

Hadicke,)Acta)Cryst.)1986,)C42,)189;)195)

Klebe,)Acta)Cryst.)1989,)B45,)69.)

Wurthner,)Chem.)Eur.)J.)2007,)13,)450)–)465

π@stacking#distance#(d)#0.335#(graphite)#–#0.43#(distorted)#nm#Generally,#most#π@interac5ons#result

in#d@spacing#around#0.38#nm#

Highly efficient molecular stacking Such ideal stacking is difficult to achieve because of side-chains association and energy balance by optimizing the lateral, and transverse offset

1D- assembly Pathway for rapid change movement


Research Summary

5 [email protected]

Self-Assembly of PTCDI

Propoxyethyl-PTCDI (PE-PTCDI)

Time dependence (methanol)

Balakrishnan)et)al.,)JACS,)2005,)pp10496

A

Molecular behavior- well defined absorption - - Fluorescence

Aggregation behavior - Formation of crystals phase - Quenching of free molecule emission

High solubility in chloroform with short side-chains for PE-PTCDI


Research Summary

6 [email protected]

Self-Assembly of PTCDI

Balakrishnan,+et+al.+JACS,+2006,+pp7390+25 µM Ethanolic solution

Side%chain*effect*


Research Summary

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Self-assembly: Toolkits for solution processing

A- Dispersion - Rapid approach injection of components into ‘poor’ solvents B- Phase-transfer: Slow diffusion of molecules from ‘good’ to ‘poor’ solvents C - Phase transfer at high temperature: Controlling the rate of diffusion by improving solubilityD- Gelation: Coercing components to maximize molecular interactions (useful in non-planar systems) E - Vapor phase treatment: Another slow diffusion process to control size, and shape of assemblies


Research Summary

8 [email protected]

Some more examples for Self-Assembly of PTCDI

Sayyad,)Balakrishnan)et)al.)manuscript)under)preparaJon

2D-assemblies

Controlling nature, and size of functionalization (i.e., side-chain) enables influencing solubilities and using the solution processing toolkit allows for controlling size, and shape of resulting assemblies. In turn this allows for fine tuning optical and electrical characteristics.

Ultralong fluorescent wires

Balakrishnan)et)al.)manuscript)under)preparaJon

Tuning light emission

Under UV-light excitation length of wires ~5 mm

Under ambient conditions

Balakrishnan,)et)al.)JACS,)2006,)pp7390


Research Summary

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Self-Assembly of Macromolecular Building Blocks

Arylene#Ethynylene#Macrocycles#(AEMs)#•'Shape'persistent'πAsurface;'πArich'nonAcollapsible'core'(rigid);'Planar'(near'planar);'''•'Large'area;''Pores'filled'with'ac9ve'func9onal'material.'(Hybrid'systems:'Applica9ons)

Highly'organized'1D'assembly'

Hoger,)Chem.)Eur.)J.)2004,)10,)1320

For 1D nanostructure – Control lateral association

J.S.Moore,Acc.Chem.Res,1997,402O413.

Nanofibers from a tetracyclic non-planar

building block

Balakrishnan)et)al.,)J.)Am.)Chem.)Soc.;'2006;'pp6576'

Nanofibers from a tetracyclic planar

building block

Such structures open new possibilities in sensing applications (see slides on Applications of self-

assembles structures )


Research Summary

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Self-Assembly of Benzothiadiazole (BTD) Building Blocks

Balakrishnan)et)al.)Chem.)Commun.)2012,)pp11668

Ultra-long fluorescent micro-tube assembly

Planar yet flexible - how does this influence morphology?


Research Summary

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Applications: π-rich self-assembled structures

J.Am.Chem.Soc. 2007, pp7234

Influence of molecular ordering: Enhanced Electrical Properties3-5x current flow upon doping

Doping of molecular wires

Influence of molecular ordering: Enhanced Sensing of Explosives

J.Am.Chem.Soc. 2007, pp6978

11


Research Summary

[email protected]

Applications of π-rich self-assembled structures

Optical Waveguides Tunable Light Emission

TgHCC-60TgHCC-60

UV-Photodetection System

Org

anic

Sol

ar C

ells Polarized Light Emission

Chem. Commun., 2012, pp11668

Chem. Commun., 2014, pp5600Chem. Commun., 2012, pp11668

J. Phys. Chem. B,, 2006, pp12327Chem. Mater., 2009, pp2930

12


Research Summary

[email protected]

Self-assembly: Dimension and size control from π-rich moleculesSolution Processing Toolkits

2D 3D micro-G

F

H I

Functional structures:

J.Am.Chem.Soc., 2005, pp10496 J.Am.Chem.Soc. 2006, pp7390 J.Am.Chem.Soc. 2006, pp6576 J.Am.Chem.Soc. 2007, pp6978 J.Am.Chem.Soc. 2007, pp7234 J. Phys. Chem. B,, 2006, pp12327 Nanoscale, 2011, pp3605 Chem. Commun., 2012, pp11668 Chem. Commun., 2014, pp5600 Chem. Commun., 2012, pp8904 Chem. Commun., 2013, pp684 Chem. Mater., 2009, pp2930 Unpublished results

13

✓Applica5ons#✓'Op9cal'Sensing'✓'Electrical'Response'✓'OptoAelectronic'response'✓'Tuning'absorp9on'✓'Tuning'light'emission'and'bandAgap'

✓'Polarized'light'absorp9on' and'emission'

✓'Molecular'materials'for'Display''

✓'Exploring'new'chemical'pathways'

from'selfAassembled'structures

Conclusions• Morphology control via self-assembly can be an effective

approach to achieve new functional properties • The advances in toolkits and synthetic advances to tailor make

desired structures are furthering the scope of applications • Recent advances with co-assembled structures and post

chemical control over self-assembled structures are paving new frontiers in materials science

• The chemical, physical, and structural diversity enable addressing new challenges (see applications)

Self-assembly-sides 1_RFS

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