Polymer Nanocomposite Conjugated

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Conjugated

Polymer

Nanocomposite

Towards a Novel Material

for Thermal Energy

Microharversting

Daniela Galliani

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Wearable Thermoelectric

Microharvesters

2

Project

Overview

p type leg n type leg

Kim, S. J., We, J. H. & Cho, B. J. A. Energy Environ.

(3)

• Low thermal conductivity

k=0.2-0.4 WK

−1

m

−1

• Medium-high electrical conductivity

σ=10-1000 Scm

−1

• Tunable electronic properties

• Easy processing

• Safety

• Environmental stability

• Low cost

• Adaptability to flexible substrate

Conjugated Polymers

Introduction

3

Bubnova, O. et al. Semi-metallic polymers. Nat. Mater. 13, 190–4 (2014) Year 2010 2011 2013 2013 2014 2014 2014 2014 2014

… efficiencies still low in comparison with inorganic benchmark

Poly(3.4-ethylendioxythiophene)

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Conjugated Polymer

Nanocomposite

Introduction

4

Q. Wei, M. Mukaida, K. Kirihara, Y. Naitoh, and T. Ishida, Materials (Basel).8, 732 (2015).

Year 2013 2010 2010 2013 2014 2014 2014

Nanomaterial

Synthesis

Method

Composition, polymorph, dimensionality… In situ polymerization, solution mixing, physical mixing…

Wide variety of

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Energy Filtering Effect

5 E Crystalline domains Amorphous zone E_f E_f E_f

Polymer Nanoparticle Polymer Vacuum level

Conduction Band

Valence Band Introduction

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Energy Filtering Effect

6 E Crystalline domains Amorphous zone E_f Polymer Nanoparticle Polymer

Vacuum level Introduction

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Energy Filtering Effect

8

Introduction

CHOOSING CRITERIA

 Intimate contacts between CP

and NPs

 Similar work functions of the CP

and the NPs

 Interfacial barrier height below

100 meV

Chemical interaction

between CP and NPs

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E

XPERIMENTAL

W

ORK

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Mn

₃

O

₄

Nanoparticles

10

Experimental Work

Starting salt

Size control agent

Reagent

T (°C) Size SEM determined (nm)

MnCl_2∙4H₂O Ethanolamine H₂O 25 25±6

«Coprecipitation» method

Mn

₃

O

₄

p-type material

work function: 4,4 eV

Starting salt solution NPs suspension

S. Lei, K. Tang, Z. Fang, and H. Zheng, Cryst. Growth

Des. 6, 1757 (₂₀₀₆₎

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Nanoparticle

Functionalization

11

Experimental Work

Phase separation

_{Homogeneous dispersion}

Mn

₃

O

₄

NP

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Hybrid Film Making

12 Experimental Work

T=-20°C

Substrate (Kapton®) 1) Solution deposition Blade

2) Solution spreading 3) Film drying

FeTos

₃

Base Solvent

Mn

₃

O

₄

NPs decorated

with glutaryl-EDOT

EDOT

Mn3O4

NP

In situ

polymerization

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R

ESULTS

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0 _1x1015 2x1015 3x1015 4x1015 5x1015 75 100 125 150 175 200 225 250  dry (  -1 cm -1 ) NP concentration (cm-3)

Thermoelectric

Characterization

14 [NP] (cm-3₎ σ_dry (Ω-1_cm-1₎ α_dry (µVK-1₎ PEDOT:Tos 0 242±9 15.8±0.9 HF1 1.5.₁₀14 _240±9 _14.8±0.5 HF2 3.0.₁₀14 _147±6 _15.5±0.7 HF3 2.2.₁₀15 _98±4 _15.0±0.2 HF4 3.0.₁₀15 _89±3 _15.5±0.8 Results [NP]: NP density σ: electrical conductivity α: Seebeck coefficient e: electronic charge (1.6×10-19_C)

p: charge carrier density (holes) [cm-3_]

μ:charge carrier mobility [cm2_/(V·s)]

μ₀, μ₁, N₀: constants

𝜎 = 𝑒𝑝(𝜇

₀

+ 𝜇

₁

𝑒

−

𝑁𝑃 𝑁

Τ

0

)

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Humidity Effect

Results

Detrimental effect on σ:

Water interposition between polymer chains

Loss in hole mobility

Gain in hole density

Beneficial effect on σ:

Counterion solvatation 16 0.3-0.4 nm

Negligible in

NP presence

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17

Results

Humidity Effect



[ ]/ 0



w

,[

]

0 1

(

)

NP N

ep x

NP

e



_

m

_

m







w w w 0 w 0

)

(0,[

])

(

,

[

]

1 [

])

w _x

p

NP

x

p

NP x

p x

N

x

P







_







_

_











[NP]: NP density σ: electrical conductivity e: electronic charge (1.6×10-19_C)

x_w: water molar fraction

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18

Humidity Effect

Understanding parameters

Parameter β (variation of p due to x_w) exponential decay vs [NP]

Water molecules sequestration by NPs

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Results obtained:

• A novel protocol to obtain hybrid material CP/INPs has been

developed

• Understanding of morphology related aspects of the

developed system

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Conclusions and Further

Developments

Conclusion

20

Further Developments:

• Development of a strategy to avoid nanomaterial detrimental

effect on morphology

1. Implement polymerization and post-polymerization treatments to

favor the rearrangements of NPs (head-to-tail)

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Thank you for your kind

attention!

21

Aknowledgments

University of Milano-Bicocca

IENI-CNR Padova

Thermoelectrics Group:

Professor Dario Narducci, Dr. Bruno Lorenzi, Dr. Laura Zulian

LaSMO Group (Organic Synthesis):

Professor Luca Beverina, Dr. Mauro Sassi

Electrochemistry Group:

Professor Riccardo Ruffo