Organic Semiconductor Optoelectronics.

Ifor D. W. Samuel1,

P. Manousiadis1, H. Chun2, A.K. Bansal1, H. Nguyen1

A. McNeill1, J. Ferguson3, S. Ibbotson3, A. Kanibolotsky4, P. Skabara4, M. Dawson5, D. O’Brien2, H. Haas6 and G.A. Turnbull1

1. Organic Semiconductor Centre, University of St Andrews

2. Communication Research Group, University of Oxford

3. Ninewells Hospital, Dundee

4. Pure and Applied Chemistry Department, University of Strathclyde

5. Institute of Photonics, University of Strathclyde

6. Photonic Materials and Devices Group, University of Edinburgh

Photo: A. Thompson

Organic Semiconductor Optoelectronics

Ifor Samuel, University of St Andrews

Outline

Introduction

- light, optoelectronics

- organic semiconductors

New applications

- in medicine

- in visible light communication

- in sensing

www.google.co.uk

Dr. Paul Shaw


Light

Dr Dimali Vithanage

www.scotlandforgolf.co.uk

www.space.com

en.wikipedia.org


Light

Communication Display

Dr Dimali Vithanage en.wikipedia.org


Semiconducting Polymers

C

C

C

C

C

C

C

C

C

C

H H H H H

HHHHH

C

C

C

C

C

Conjugated polymers can conduct electricity

polyacetylene

Actually semiconductors

Heeger, MacDiarmid, Shirakawa, Nobel prize 2000


Organic Semiconductors

Conjugated molecules

Novel semiconductors

Easy to process

Can tune properties

Can emit light

Flexible

6


Semiconductor Devices

Transistors

Light-emitting diodes

Solar cells

Light sensors

Lasers

[1] Photo of organic solar cell from xpsolar.com


Organic Light-Emitting Diode (OLED)

metal contact

organic semic.

transparent contact

substrate

-

+

- -

++

+ -

Light-emitting diode (LED)

Tang and van Slyke: Small Molecules

Burroughes, Bradley, Friend: Conjugated polymers


Examples of OLED Displays

LG display

Dynamic lighting

Samsung flexible phone LG OLED curved TV LG OLED rolled TV

http://freshome.com

http://gadgets.ndtv.com

http://www.cnet.com

http://oled-news.blogspot.co.uk

http://mtnblog.co.za

University of St Andrews 10

Organic Semiconductor Centre

Organic Semiconductor

Centre

Visible light communication

OLEDsLasers

OPV

Biophotonics

Sensing

Photophysics/materials


Outline

Biophotonic applications

Skin cancer treatment

Muscle contraction sensor

Visible light communication

Polymer Laser Sensors

G.E.

12Ifor Samuel, University of St Andrews

Trends in Medicine

Continuous monitoring

Ambulatory monitoring/treatment

Optoelectronic devices non-invasive

Conjugated polymers

Enable thin, flexible devices

Wearable devices for monitoring and treatment

Wearable Devices for Biology and Medicine

www.amazon.co.uk

www.ece.villanova.edu

curaderm.olmifon.net

http://www.ece.villanova.edu/

http://curaderm.olmifon.net/tag/alternative-health/

13

Skin Cancer

Treatment of skin cancer with light

• 15% of UK, 40% of

American and 75% of

Australian population

develop a skin cancer

during their life time

• 98,000 people are diagnosed

with non-melanoma skin

cancer each year in the UK

• Around 90% of the tumours

are on the face and neck,

surgery can be complex and

leave scars

• 491 deaths each year in the

UK from untreated non-

melanoma skin cancer



Photodynamic Therapy (PDT) of Skin Cancer

Illumination of tumour region with high intensity light source for 20 minutes

Presence of light causes PP9 to produce singlet Oxygen leading to local cellular destruction within the tumour only

Application of ALA or Metvixcream at tumour site

ALA or Metvix metabolised to Light sensitive Protoporphyrin 9 only within the tumour

15

Conventional PDT


BCC before & after PDT x3


Potential of OLEDs for PDT

• Uniform illumination

• Lightweight - can be worn

• Allows low intensity/long treatment– Reduced pain, increased effectiveness

• Low cost - disposable– Attractive for hygiene

– Widens access to PDT

• Simple wearable power supply

• Scope for ambulatory treatment1

– At work

– At home

1. Moseley et al Brit. J. Derm. 154, 747 (2006)

Ifor Samuel, University of St Andrews 18

Device Applied

Device Worn During

Normal Daily Activities

Device Disposed

Wearable Organic Optoelectronic Source for PDT

OLED-PDT

BioEL 2015, Kirchberg



OLED PDT: Before and After

Before Treatment After Treatment

Pilot study Attili et al Brit. J. Derm. 161, 170 (2009)


PDT Pain Results

• Ambulatory PDT provides a large reduction in pain for most patients• 50% reported pain score ≤ 2

• In a preliminary study, 16/19 patients that used both conventional and ambulatory PDT, preferred ambulatory. 1

1. Ibbotson et al, Photoderm. Photoimmun. & Photomed., 28, 235


Ambulatory PDT Trial Results and Benefits

• Trial Results at 12 month follow-up• 67 patients with 90 lesions (42 BCC, 47 Bowens, 1 AK)• 80 clear, 10 partial response• 89% clearance at 12 months, compared to 70-100% for

conventional PDT1.• Achieved with one tenth the intensity for ten times as long• Avoids pain

• Ambulatory treatment demonstrated• More comfortable• Possibility of treatment at GP or home• Potential to be low cost, disposable• Lower intensity for longer time avoids pain

• Plus all the benefits of regular PDT.

Current Prosthetic Sensors

Mechanical

Connection

Signal

Connection

Electromyography Sensors

Piezo-cable Sensors

Piezo-thin film Sensors

Back force Sensors

Drawbacks of Electrical based sensors

- EM interference

- Painful due to needles

- Immune response

We can solve the issues by

Optical Sensors

Optical Flexible Muscle contraction sensor

www.zeitnews.org/life-sciences


• Muscles are intrinsically fibrous

• Light scattering by the muscle is anisotropic

• Fibre Aspect Ratio changes when muscle is contracted

Working principle of optical sensor:

• Changes in amount of scattering signals contraction


Sensor implementation: Shine light into muscle – light is scattered in all directions through the muscle

Place four photodiodes on vertices of a square round source

Subtract the parallel and perpendicular photocurrents

When muscle is contracted more light reaches the perpendicular photodiodes

– causes a change in output

Use amplifier to give output voltage indicating muscle contraction


Flexible OLED/OPD Fabrication

ITO

PET or Glass

PEDOT

Active layer

Ca/Al

26

PTB7 PCBM(C70)

OLED

Organic photodiodes

SPIE 2016, San Diego


Flexible Sensor; Types of Muscle Contraction

• Isotonic contraction – constant force

• Isometric contraction – constant length


Optical Signal for Muscle Contractions

• Isotonic and isometric contractions can be obviously distinguished

• Blood depletion and refilling detected

Ifor Samuel, University of St Andrews28

Isometric and Isotonic Muscle Contraction of Biceps


Control of Robotic Arm by Muscle Contraction Sensor

Isotonic Muscle Contraction of Deltoid

Control of Robotic Arm by Muscle Contraction Sensor


University of St Andrews

Vision of VLC

HHI, ExtremeTech

Collaboration with D. O’Brien, H. Haas, M. Dawson


VLC principles

Data in

Data out

VLC principles Data from the transmitter side

are sent to the receiver side by light in free space.

The light’s properties (e.g. intensity, phase, signal frequency) are modulated to care information.

The driving signal is voltage.

VLC principle

TxTransmitter Receiver

GaN LED: τ≈10 nsec

Wavelength ConverterPhosphor: τ≈1 μsecOSC: τ <10 nsec

Phosphor bottleneck Phosphor-based LEDs:

blue LED + Yellow phosphor

VLC bottleneck: 𝜏𝑌𝐴𝐺:𝐶𝑒 ≫ 𝜏𝐺𝑎𝑁.


Materials for Colour Conversion

Materials requirements

Absorption at 450 nm

High solid state PL quantum yield (>50%)

Short radiative lifetime (<5 ns, preferably <2 ns)

Emission across visible

Photostable

33


Materials for Colour Conversion - Lifetime

34

0 10 20 30 40 5010

100

1000

10000

PL

in

ten

sity (

co

un

ts/s

)

Time (ns)

CL-827

Inorganic Phosphor:

Y3Al5O12:Ce3+

Organic Semiconductors

CdSe600

0 10 20 30 40 5010

100

1000

10000

PL

in

ten

sity (

co

un

ts/s

)

Time (ns)

CL-827

CdSe QD

0 10 20 30 40 5010

100

1000

10000

PL inte

nsity (

counts

/s)

Time (ns)

CL-827

CdSe QD

Y-B3

0 10 20 30 40 5010

100

1000

10000

PL

in

ten

sity (

co

un

ts/s

)

Time (ns)

CL-827

CdSe QD

Y-B3

SY

0 10 20 30 40 5010

100

1000

10000

PL inte

nsity (

counts

/s)

Time (ns)

CL-827

CdSe QD

Y-B3

SY

BBEHP-PPV


Bandwidth of comm. channelBandwidth of communication channel The data rate is proportional to

BW of the system. Range of frequencies available to

carry signals. Αttenuation of the amplitude a(ω)

of the received signal normalised to a(ω=0). 0

0.2

0.4

0.6

0.8

1

0 0.1 0.2 0.3

a(ω

)/a(ω=0

)

Frequency (GHz)

Βandwidth

Schematic of setup for BW&DR measurement

Bandwidth measurements

0 20 40 60 80 100

-5

-4

-3

-2

-1

0

T4BT-YB3

Super Yellow

BBEHP-PPV

CL-840

Y-B3

Att

enu

atio

n (

dB

)

Frequency (MHz)


White VLC Record Data Rates

0.00001

0.0001

0.001

0.01

0.5 1.5 2.5

BER

Gb/s

White VLC @ 3 cm using SY solution

White VLC @ 2 m using SY film

Use high BW yellow PL material for white VLC Dichromatic white light was produced Orthogonal frequency-division multiplexing was

used. Record Data Rates for White VLC were recorded

Bit Error Rates vs Data Rates using OFDMWhite VLC@2m

White VLC@3cm

µLED@2m

H Chun et al, PTL (2014), LED provided by Strathclyde University, M. Dawson et al.


Organic Semiconductors in VLC

HHI, ExtremeTech

Colour converters

OLEDs

Directional LEDs

Luminescent concentrators OPVs

Organic Semiconductor Lasers

Photo G. Tsiminis


Distributed Feedback Lasers

2st order diffraction -

feedback

1st order

diffraction- output

coupling

2st order diffraction -

feedback

Periodic waveguide structures “reflect” waveguide modes

Beff mn 2


Laser application: Explosive sensing

Organic semiconductors: photophysical interaction for sensing Main explosives in land mines: TNT, DNT, DNB etc. Nitroaromatic compounds are strongly electronegative Presence of nitroaromatic molecule causes electron transfer and

quenches light emission

TM Swager, Chemical Reviews 107 (2007)


Laser vs PL sensing

0 100 200 300

0.6

0.8

1.0

Laser Sensing

No

rma

lize

d

Em

iss

ion

(a

.u.)

Time (s)

PL Sensing

Laser sensing 40% quenched @ 1 min

PL sensing 34% quenched @ 5 min


Conclusions

Background Photo: Edward Simpson, CC-BY-SA

• Organic semiconductors – processable, tuneable optoelectronic materials

• Distinctive properties enable new applications

• Wearable Organic Optoelectronics for Medicine

• Skin cancer treatment by PDT

• Muscle contraction sensor

• Visible light communication

• Record data rate for white VLC

• Polymer Laser Sensor

• Can detect explosives, drugs


OSC group


ERPOS 2017

Electronic and Related Processes in Organic Solids Long-running (since 1974) organic electronics conference July 9-13, 2017 www.erpos.org

44

http://www.erpos.org/

Organic Semiconductor Optoelectronics.

Science

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