Hilmi Volkan Demir - KTH

Nanophotonics to Combat Climate Change and 

Energy Problem 

ADOPT 

Winter School 2010 

Romme Romme, , Sweden 

March 11 11-14, 14, 20 2010 10 

Nanophotonic Solutions for High-Quality Solid State Lighting 

Hilmi Volkan Demir 

Department of Electrical and Electronics Engineering 

Department of Physics 

National Institute of Materials Science and Nanotechnology 

Bilkent University, Ankara 

Semiconductor Lighting Research Center 

Nanyang Technological University University, Singapore 

volkan@bilkent.edu.tr | hvdemir@ntu.edu.sg 

volkan@stanfordalumni.org 

TÜBA

Outline 

• Climate change, greenhouse gases 

• Solid So d state lighting g t geenabled abedby by nanophotonics 

a op oto cs 

– White LEDs involving nanophosphors 

– for indoors lighting (warm color temperature, high color rendering index) 

– for tuned color chromatictiy operation (tuned tristimulus coordinates) 

– Nonradiative energy transfer in nanophosphors 

– FRET enhanced color converted LEDs 

– FRET converted light emitting structures 

– color tuning with FRET 

– Plasmonic nanophosphors 

– plasmon coupling using metal nanoparticles 

– selective plasmon coupling of white luminophors 

• Conclusion 

Hilmi Volkan Demir

… a very unfortunate unfortunate, upsetting fact 

Our World is being POLLUTED POLLUTED… 

[1] IPCC Climate Change 2007 2007, Human and Natural Drivers of Climate Change, Change Summary for Policymakers Policymakers, pp pp. 2 (2007). (2007) 

[2] Donald Kennedy, Climate Change and Climate Science, Science, 304, 1565 (2004). 


Global warming?, climate change 

IPCC Climate Change 2007, “Is the Current Climate 

Ch Change UUnusual l CCompared d tto EEarlier li Ch Changes iin 

Earth’s History?,” (2007), 


What factors determine earth’s climate? 

[1] J. T. Kiehl and K. E. Trenberth,” Earth’s Annual Global Mean Energy Budget,” Bulletin of the American Meteorological Society, 78, pp. 206 (1997). 

[2] Also in IPCC Climate Change 2007, “What Factors Determine Earth’s Climate?,” chapter 1, pp. 96 (2007), 


• Natural causes 

Greenhouse gases 

– Natural greenhouse gas effect (water vapor) 

– Radiative forcing and forcing variability from natural changes (i.e., solar 

changes) 

• Anthropogenic (human‐related) causes 

– Increase of greenhouse gases 

• Carbon dioxide 

• Nitrous oxide 

• Methane 

• Halocarbon (a group of gases containing fluorine, chlorine and bromine) 

• Ozone 

Anthropogenic causes must be taken under control … 

IPCC Climate Change 2007, “How do Human Activities Contribute to Climate Change and How do They Compare with Natural Influences?,” 

FAQ chapter, pp. 100 (2007). 


Carbon dioxide 

IPCC Climate Change 2007, “How Do Glacial-Interglacial Variations in the Greenhouse Gases Carbon Dioxide, Methane and Nitrous Oxide 

Compare with the Industrial Era Greenhouse Gas Increase?,” Chapter 6, pp. 448 (2007). 


Climate change 

Drought Acid rain 

Flood 

Global Warming 

Ice melt

CO 2, temperature change, and 

sea level 

Relation between estimated atmospheric 

CO2 and the ice contribution to sea level 

[1] 

An example: Changes in key global climate parameters since 

1973, compared with the scenarios of IPCC (shown as 

dashed lines and gray ranges) [2] 

Measurements taken at Mauna Loa (Hawaii) 

[1] R. B. Alley, et al., “Ice-Sheet and Sea-Level Changes,” Science, 310, 456 (2005). 

[2] S. Rahmstorf, et al., “Recent Climate Observations Compared to Projections,” Science 316, 709 (2007). 


Changes in snow, ice, and frozen ground and rising sea level 

Rate of ice mass loss from all 

GIC (glaciers & ice caps) since 

1995. 

“This acceleration of glacier 

melt may cause 010to 0.10 to 025 0.25 

meter of additional sea‐ 

level rise by 2100.” 

Ma. F. Meier et al., l “ “Glaciers l Dominate Eustatic Sea‐Level l Rise in the h 21st Century,” ” Science, 317, 1064‐1066 ( (2007). 

) 


Problems in ecology 

• According to Thomas’ work, some species 

have the risk of becoming extinct due to the 

effects of global warming. Between 15% ‐ 

37% of known species will be extinct by 

2050. [1] 

• “The synergism of rapid temperature rise 

and other stresses, in particular habitat 

destruction, could easily disrupt the 

connectedness among species and lead to a 

reformulation of species communities, 

reflecting differential changes in species, 

and to numerous extirpations and possibly 

extinctions.” [2] 

[1] C. D.Thomas et al., Extinction risk from climate change, Nature, 427, 145-148 (2004) 

[2] T. L. Root et al., ‘Fingerprints’ of global warming Hilmi on wild Volkan animals Demir and plants,” Nature, 421, 57-59 (2003).

Why do we produce so much CO 2? 

• The largest source of CO2 

emission is globally the 

combustion of fossil fuels (e.g., 

coal, oil, and gas in power plants 

and industrial facilities). 

• The main reason of CO2 

emission is the need for energy. 

• Lighting uses ~19% of global 

electricity generation. 

• In homes and offices, up to 50% 

of total energy consumption is 

due to lighting. 

References: EPA (U.S. Environmental Protection Agency) U.S. 

Greenhouse Gas Inventory Reports 1990 – 2005, Carbon Dioxide 

Emissions, Executive Summary, pp. 6-7, 2007 


1997 

2009 

How are we doing? 

Kyoto Protocol (United Nations Framework Convention on Climate Change)

Let’s Let s Combat Climate Change… 

• Decisions made to halt 

climate change 

• e.g., European Union 

Göteborg agreement 

8 Sustainable healthy life 

� Reduction in energy consumption 

� Increase in alternative energy sources 

� Decrease in polluting emission 


Can nanotechnology help to combat climate change? 

• … the answer is YES (but a cautious yes). 

• For example, 

– Spectrally p yppure lighting g g 

– Photovoltaic technology 

– Batteries and supercapacitors 

– IImproved di insulation l ti ffor houses h and d offices ffi 

– Fuel additives to increase the efficiency of diesel engines 

– … 

• Nanoparticles already in use 

– Functional nanocomposite coatings (e.g., (e g Innovnano Innovnano, Innovcoat) 

Nature Nanotechnology, “Combating Climate Change”, 2(6), 325 (2007). 


How can we combat climate change using 

NANOPHOTONICS? 

• Can we help to reduce global energy 

consumption by high high‐quality quality 

semiconductor lighting? 

• Can we seek ways to improve efficiency in 

solar energy conversion? 

• Can we help to reduce the amount of 

greenhouse gases? 


How can we combat climate change 

using NANOPHOTONICS? 


consumption? 

– Light generation 

• Solid state lighting using nanophosphors 

– for the generation of high‐quality white light 

– using nonradiative energy transfer 

• Can we help to convert solar energy more 

efficiently? 

– Light harvesting 

• Quantum dot integrated solar cells 

– for the extension of spectral response 

– also using nonradiative energy transfer 

• C Can we help h l t to reduce d the th amount t of f 


– Photocatalytic nanoparticle integrated systems 

• ffor massive i environmental i t ld decontamination 

t i ti 


GREEN 

NANOPHOTONICS 

current (mA) 

* 2 patents pending 

voltage (V) 

0 

0 02 0.2 04 0.4 06 0.6 08 0.8 1 12 1.2 14 1.4 16 1.6 18 1.8 2 

-2 

-4 

-6 

-8 

PL Intensity (a.u.) 

* 1 patent p 

* 3 patents 

350 400 450 500 550 600 650 700 

λ (nm) 

wihout nanocrystals 

with 3.42 nanomol/cm2 nanocrystals 

with 10.40 nanomol/cm2 nanocrystals y 



with 67.60 nanomol/cm2 nanocrystals

Outline 


• Solid state lighting enabled by nanophotonics 













How does solid state lighting (SSL) help in combating 

climate change? 

• Artificial lighting uses about 19% of the global 

electricity generation worldwide. 

• Th The IInternational t ti lEEnergy A Agency (IEA) hhas 

estimated that the energy needed to produce 

lighting induces approximately 1900 Mt CO2 emission per p yyear, which is equivalent q to 70% of the 

emissions from the world’s passenger vehicles. 

•The energy consumption used for LEDs lighting 

could be reduced by 50%, if the target performance 

is met met. 

•This is equivalent to carbon emission reduction of 

many hundreds of million tons per year. 

LED‐based luminescence system will 

be the next generation of lighting 

source! 

Source: International Energy Agency, “Light’s labour lost: Policies for 

energy‐efficient lighting, in support of the G8 plan of action,” p.558 

(2006).

Luminous efficacy e 

η (lm/We) 10 3 

10 2 

10 1 

1 

10 ‐1 

10 ‐2 

Efficiency of artificial lighting 

CoL ($/Mlmh) ≃ CoE/η 

1 

10 1 

10 2 

FSU 2000 

CN 2005 

CN 2006 

US 2001 

UK 2000 

AU+NZ 2005 

WRLD-NONGRID 

1999 

10 3 

10 1.5 

WRLD-GRID 2005 

JP+KR 2005 

OECD-EU 2005 

CN 1993 

10 4 

UK 1950 

UK 1900 

UK 1850 

10 5 

100% 

Efficiency 

1 101 102 103 104 105 1 101 102 103 104 105 CoE ($/MW eh) 

UK 1800 

UK 1750 

UK 1700 

10 2.8 

SSL 

HID 

Fluorescent 

Incandescent 

Gas 

Kerosene 

Candles 

Source: Tsao and Waide, “The World’s Appetite for Light: Empirical Data and Trends Spanning Three 

Centuries and Six Continents,” Sandia National Labs, USA 

Artificial lighting has made an incredible 

progress from candles, gas and kerosene 

lamps to incandescent, fluoroscent and 

high‐intensity discharge electric lighting. 

• 28 2.8 orders d of f magnitude it d decrease d in i the th 

generation 2.8 orders cost of light. 

•1.5 orders of magnitude decrease in cost of 

energy. 1.5 orders 

• Th The overall ll operating ti cost t of f light li ht has h been b 

reduced by 4.3 orders of magnitude since 

1700s. 4.3 orders

Motivation for white LEDs (WLEDs) inSSL 

For developed and developing countries 

TODAY 

Current lighting g g technologies g consume: 

19% of the global electricity production 

WLEDs provide: 

For under-developed part of the world 

FUTURE 

TODAY FUTURE 

Fuel based lighting provides 

>1B people who does not have access to 

electricity: 

Unhealthy 

Costly 

Low light quality 


50% reduction in electricity consumption 

Reduction in carbon emission by 100s M tons 

per year 

WLEDs provide: 

Healthy 

Affordable 

High-light quality

The Earth at night from a satellite 

• We consume lots of light! 

• And this h costs us llots of f energy … 

Source: C. Mayhew and R. Simmon (NASA/GSFC), NOAA/ NGDC, DMSP

Potential market of LED‐based products 

The market size of LED‐related business is 

expected to be about USD USD 4 billion 4 billion for 2015, 

with the annual demand growth of of 14%

White LEDs 

Two most common methods for WLEDs 

� RGB LEDs: using 3 different 

(red-green-blue) LEDs 

� Color conversion LEDs: using 

luminescent materials (luminophor) 

on LEDs 

typically phosphors: EL of LED and 

PL of luminophors collectively generate 

white light 


Thin-Film Flip Chip (TFFC)

Phosphors vs. Nanophosphors 

Broad emitters, difficult to control precisely 

Yellow phosphors, color rendering index (CRI) ~ 70 

Cool white appearance due to high correlated color 

temperature (CCT)~4000 -8000 K 

Red-green phosphors, CRI / CCT can be improved, but 

this comes at the cost of reduced luminous efficacy of 

optical radiation. 

Problems: stability, granularity, source of rare earth 

elements 


Narrow emitters, possible to control precisely 

PL Intensity(a.u) 

I 

1.0 

0.8 

0.6 

0.4 

0.2 

0.0 

500 550 600 650 

wavelength(nm) 

Cyan 

Green 

Yellow 

Red 

Using combinations of semiconductor 

quantum dot nanophosphors, It is 

possible to achieve warm white light 

CCT300 lm/W. l /W 

Superior photometric performance. 

Problem: Quantum efficiency is being 

improved. Further improvements required. 

Our focus: high optical quality WLEDs using quantum dot 

nanophosphors with specific spectral content of emission

White light generation 

Color matching function 

Color-rendering index (CRI) 


[1] E. F. Schubert, Light Emitting Diodes, [2] Audi 

C.I.E. chromaticity diagram 

Correlated color 

temperature p (CCT) ( )

Important photometric properties 

Figure of merit Explanation Unit 

Chromaticity locus of the perceived color 

coordinates 

(x,y) 

Color rendering 

index (CRI) 

on the chromaticity 

diagram 

ability to render true colors 

from illuminated objects 

index (CRI) from illuminated objects - 

Correlated color 

ttemperature t 

(CCT) 

Luminous efficacy 

of optical 

radiation (LER) 

temperature of the planckian 

bl blackbody kb d radiator di t K 

closest in color 

usable radiation for human 

eye per optical power 

- 

lm/W 


Color chromaticity 

• Colors are defined using color matching functions and chromaticity 

diagram diagram. 

E. F. Schubert, “Light Emitting Diodes,” 

Cambridge University Press (2006) 28

Luminous efficacy (LE 

Luminous 

(LE or LER) 

• Optical efficiency of the light source perceived by the human eye 

Incandescent sources: 1 16 lm/W 

Fluorescent lamps: 1 Fluorescent lamps: 71 lm/W 

Phosphor based WLEDs: 2 274 lm/W 

1: Navigant, U.S. Lighting Market Characterization Volume I: 

National Lighting Inventory and Energy Consumption (2002). 

Estimate 

2: M. R. Krames et al., J. Disp. Technol. 3, 2 (2007). 

www.theoremeinnovation.com/revo 

lution-en.html 

29

Color rendering index (CRI) 

• A measure of how good the light source can render the real colors of the 

illuminated objects 

• Maximum value is 100, minimum value is ‐100 

• Developed by International Commission on Illumination (CIE) 

• The calculation is based on 

� The reflection of the test light from test samples 

�� Th The reflection fl ti of f the th reference f light li ht from f test t tsamples l 

� Reference light is in general a blackbody radiator 

� A good source should have a CRI >80 to start competing with other conventional 

sources 

http://www1.eere.energy.gov 

/buildings/ssl/measuring_cri. 

html 

30

Correlated color olor temperature (CCT) 

• Illustrates the temperature of the closest Planckian black black‐body body radiator to 

the operating point on the chromaticity diagram. 

• As opposed to common usage in thermodynamics 

• High CCT → bluish light → cold white 

• Lower CCT → reddish light → warm white 

• Warm white light is more desirable 

• CCT < 3000 K 

http://www.answers.com/topic/colorttemperature 

t 

Warm 

white 

31

Conventional white light sources 

Incandescent lamp spectrum 

http://www.gelighting.com/na/business_lighting/education 

_resources/learn_about_light/distribution_curves.htm 

Fluorescent 

lamp spectrum 

32

Nanocrystal quantum dot emitters 

525 585 605 655 

nm nm nm nm 

increasing size 

• Narrow emission (spectral purity) 

• Size tuneability (quantum size effect) 

• Broad absorption 

• Reasonable quantum yield in collaboration 


co abo at o 

with A. Eychmüller 

TU Dresden

PLL 

Intensity (a.u.) 

Principles of QD nanophosphor embedded 

WLED WLEDs 

350 400 450 500 550 600 650 700 

λ (nm) 

�Quantum efficiency 

>90% in solution, >70% in film demonstrated by 

other groups (and further improvements are in 

progress) 

�Adjustable optical spectrum, easy to tune 

�High quality white light: 

high CRI, high LER, low CCT 

34

Working principle 

energy transfer 

Physical mechanisms: 

Optical absorption 

Reabsorption 

Photoluminescence 

Dipole-dipole interaction 

(Förster-type energy 

transfer)

Design, epigrowth and fabrication 

– Epidesign p g 

– Epigrowth 

– Standard semiconductor fabrication 

• Photolithography 

• Thin film coating 

• Reactive ion etching 

• Rapid thermal annealing 


Experimental achievement 

• Successful demonstration of 

– High ihquality li of f white hi light li h generation i tuneable bl 

by design 

• using multiple (e (e.g., g triple, triple quadruple) combinations 

of nanophosphors 


White light generation tuned with nnano 

anocrystals crystals 


S. Nizamoglu, T. Ozel, E. Mutlugün, H. V. Demir 

Nanotechnology 18, 065709 (2007)

High‐quality, warm white LEDs integrated with 

nanocrystal y emitters 

• Warm white light (CCT< 3500 K) 

• Color rendering index (CRI~ (CRI 80) 

Indoors lighting (homes, offices, schools …), 

S. Nizamoglu, G. Zengin, H. V. Demir, Applied Physics Letters, 92, 031102 (2008). 


x= 0.4625 

y= 0.3255 

CCT= CCT 1982 K 

CRI= 79.55 

x=0.3881 

y=0.3177 

CCT= 3190 K 

CRI =81.00 

x=0.3799 

y=0.3018 03018 

CCT= 3228 K 

CRI=82.38

High High-quality, quality, warm white LEDs integrated 

with nanocrystal y emitters 

Sample # x y LER (lm/W) CRI CCT (K) 

1 0.37 0.30 307 82.4 3228 

2 0.38 0.31 323 81.0 3190 

3 046 0.46 032 0.32 303 79 79.66 1982 


S. Nizamoglu, G. Zengin, H. V. Demir, 

Applied Physics Letters, 92, 031102 

(2008).

Photometric modeling 

• Aim: What is the maximum feasible photometric performance achievable 

with nanophosphor‐integrated WLEDs? 

• NCs emission spectra and blue LED spectrum: Gaussian 

• 4 colors –blue – green – yellow – red 

• Parameters: 

� Peak emission wavelength 

� Full width at half‐maximum (FWHM) 

� Factors of Gaussians 

Total number of cases: 237,109,375 

•High g quality: q y CRI ≥ 90, , LER ≥ 380 lm/W, , CCT < 4000 K 

�Only 0.001% of the spectra satisfied these conditions 

•Obtaining highly efficient white light sources requires spectra 

that are controlled and tuned very carefully. 

41

• CRI vs. CCT relation: 

� Boundary behavior between 

1500 K and 2200 K is due to LER 

≥ 300 lm/W restriction. 

�� BBoundary d bbehavior h i after ft 2200 

K is fundamental behavior. 

• CRI vs. LER relation: 

� Boundary behavior is 

generated by combination 

of the trade-off between 

CRI vs. LER at different 

CCT values. 

Parametric study 

• LER vs. CCT relation: 

� Cooler white light sources 

are required to obtain 

optically efficient white 

light. 

� Boundary is shaped by the 

CRI ≥ 80 restriction. 

T. Erdem , S. Nizamoglu, X. W. Sun, H.V. Demir, Optics Express 18, 340 (2010). 

42

Photometric trade‐offs 

T. Erdem , S. Nizamoglu, X. W. Sun, H.V. Demir, Optics Express 

18, 340 (2010). 

CRI vs. LER at CCTs 

a) between 2450 and 2550 K 

b) between 2950 and 3050 K 

c) between 3450 and 3550 K 

• CRI vs. LER relations: 

� High CRI comes with the cost of reduced 

LER at all correlated color temperatures 

� Increasing CCT permits obtaining higher 

CRIs 

� Increasing CCT allows higher LER values 

�� Change of CRI with respect ot LER slows 

down at high CCTs 

43

• Full width at half-maximum 

(CRI ≥ 90 and LER ≥ 380 lm/W) 

� Blue: Average: 44.4 nm, St. 

DDev: 88.3 3 nm 

� Green: Average: 43.3 nm, St. 

Dev: 8.4 nm 

�� Yellow: Average: 44.0 440nm nm, 

St. Dev: 8.3 nm 

� Red: Average: 32.1 nm, St. 

Dev: 3.5 nm 

Parametric study 

Intensity (a.u. .) 

14000 

12000 

10000 

8000 

6000 

4000 

2000 

0 

CRI=91.3 

LER=386 lm/W 

CCT=3041 CCT 3041 K 

400 450 500 550 600 650 700 

Wavelength (nm) 

T. Erdem , S. Nizamoglu, X. W. Sun, H.V. Demir, Optics 

Express 18, 340 (2010). 

44

Multilayered heteronanocrystals 

1 

0 

1 

0 

1 

0 

1-1 

1-2 1-3 

2-1 2-2 2-3 

S. Nizamoglu and H. V. Demir, "Onion-like (CdSe)ZnS/CdSe/ZnS quantum-dot-quantum-well heteronanocrystals 

for investigation of multi-color emission," Optics Express 16(6),3515-3526 (2008). 


3-1 

1 

0 

3-2 

r 

1 

0 

3-3

Optical Poower 

(a.u) 

1.0 

0.8 

0.6 

0.4 

0.2 

0.0 

WLEDs integrated with onion‐like heteronanocrystals 

In solution 

Photoluminescence 

450 500 550 600 650 700 

wavelength (nm) 

S. Sapra, S. Mayilo, T. A. Klar, A. L. Rogach, and 

J. Feldmann, Adv. Mater. 19, 569 (2007). 

S. Nizamoglu, E. Mutlugun, T. Özel, H. 

V. Demir, S. Sapra, N. Gaponik, A. Eychmüller 

Applied Physics Letters 92, 113110 (2008). 


White light emitting diode 

(x, y)=(0.36, 0.30), CRI=75.1, and CCT=3929 K 

in collaboration 


TU Dresden

WLEDs tuned with onion‐like heteronanocrystals 

H. V. Demir, , S. Nizamoglu, g , E. 

Mutlugun, T. Özel, S. Sapra, N. 

Gaponik, A. Eychmüller 

Nanotechnology, 19, 335203 (2008). 


WLED x y 

1 0.26 0.23 

2 0.31 0.29 

3 0.34 0.30 

4 0.37 0.36 

Applications: spectral‐content 

specific illumination, e.g., shop 

lighting, museum lighting, green 

house lighting, refrigerator long‐ long 

term storage, algea growing for 

bio‐fuel, etc.

White nano‐luminophor surface state emitting 

CdS nanocrystals l 

CB 

VB 

Intensity (a.u.) 

Absorption 

Emission 

350 400 450 500 550 600 650 

λ (nm) 

S. Nizamoglu, E. Mutlugun, O. Akyuz, N. Kosku Perkgoz, H. V. 

Demir, L. Liebscher, S. Sapra, N. Gaponik, A. 

Eychmüller, New Journal of Physics 

10, 023026 (2008).

Optical Power P (a.uu) 

Surface state emitting CdS nanocrystals hybridized on n‐ 

UV InGaN/GaN LEDs 

• Tuning white light properties 

1 8 

0 

1 7 

0 

1 6 

0 

1 5 

0 

1 4 

0 

1 

3 

0 

1 

2 

0 

1 1 

0 

400 500 600 700 



Outline 















Förster‐type energy transfer (FRET) 

• FRET: nonradiative transfer of excitation energy from an 

excited molecule (donor) ( ) to a gground‐state 

molecule 

(acceptor) 

0.8 

R 

(a.u) 

Absorbance 

0.6 

0.4 

0.2 

0.0 

400 500 600 700 


2 − 4 

R 0 = 0 . 211 ( κ n Q D J ( λ 

k 

ηη 

6 

1 ⎛ R0 

⎞ 

T ( r) 

= ⎜ ⎟ 

τ D ⎝ r ⎠ 

ET 

= 1− τ 

1 

τ 


DA_ 

amp−ave 

D _ amp−ave 

)) 

1 / 6 

Energy transfer 

rate 

Energy transfer 

efficiency ffi i 

Förster 

radius 

T. Förster, Ann. Phys. VI 2, 55 (1948).

Recycling of trapped‐excitons 

Photoluuminescencce 

1.0 

0.8 

R 0.6 

0.4 

0.2 

00 0.0 

500 550 600 650 


Absorbance (aa.u) 

0.8 

0.6 

0.4 

0.2 

00 0.0 

400 500 600 700 


Spontaneous Spo ta eous emission e ss o 

enhancement using recycling 

of trapped-excitons 


Hybrid WLEDs enhanced enhancedwith with nonradiative energy 

transfer in CdSe CdSe/ZnS ZnS core/shell nanocrystal solids 

Energy transfer between nanocrystal emitters (exciton funneling): e.g., see 

S. A. Crooker, J. A. Hollingsworth, S. Tretiak, and V. I. Klimov, Phys. Rev. Lett. 89, 186802 (2002). 

TA T. A. Klar Klar, TT. Franzl Franzl, AA. L. L Rogach Rogach, and JJ. Feldmann Feldmann, Adv Adv. Mat. Mat 17 17, 769 (2005) (2005). 

WLEDs enhanced with energy transfer between nanocrystal emitters: 

u.) 

l power (a. 

Optica 

energy gradient ~ 160 meV

Relative quantum efficieny enhancement by 

recycling y gtrapped pp excitons 

S. Nizamoglu, O. Akin, and H. V. Demir, Applied Physics Letters 94, 243107 (2009).

Time‐resolved kinetics at donor emission 


Phooton 

count 

Time‐resolved kinetics at acceptor emission 

10000 10000 @ 612 nm 

1000 

100 

Photoon 

count 

1000 

100 

0 10 20 30 40 50 

time (ns) 

0 100 200 

ti time (ns) 

( ) 

300 400 

E 

1 τ 

= 1 − 

τ 

amp _ av _ DA 

amp _ av _ D 

Förster Energy 

transfer efficiency 

= 

55.58 %

Kinetics of energy transfer 

S. Nizamoglu and H. V. Demir, "Resonant nonradiative energy transfer in CdSe/ZnS core/shell nanocrystal solids 

enhances hybrid white light emitting diodes," Optics Express 16, 13961-13968 (2008).

Energy transfer enhanced WLED 

Emission enhancement of large dots residing in the mixed energy gradient assembly 

with respect to the emission of only large dots: 46% 

Enhancement in the quantum efficiency of large dots in the presence of the small 

dots, compared to the large dots alone: 13.2% 

(because of recycled excitons) 

(x,y) = (0.44,0.40) 

CCT= 2872 K

Green gap: green/yellow range 

J. M. Phillips et al., Laser & Photon. Rev., 1, 307–333 (2007). 

M. R. Krames et al., IEEE Journal of Display Technology 3, 2 (2007).

(mW) 

Opttical 

power p 

3 

2 

1 

0 

Color‐Converted LED 

Optical poweer 

Relative 

800 

600 

400 

200 

30 mA 

20 mA 

10 mA 

0 

525 550 575 600 625 650 


LE 

Optical 

⎛ lm ⎞ 

= ⎜683 

⎟ 

⎝ W ⎠ 

⎛ lm ⎞ 

LE Electrical = ⎜ ⎜683 

⎟ 

⎝ W ⎠ 

0 10 20 30 40 50 

Current (mA) 

∫ P 

∫ 

∫ 

optical 

P 

optical 

( λ) 

v( 

λ) 

dλ 

( λ) 

dλ 

Poptical( 

λ ) v( 

λ) 

dλ 

VI 

S. Nizamoglu … H.V. 

Demir, IEEE Journal of 

Selected Topics in Quntum 

Electronics Electronics, 15, 15 4, 4 July/August 

2009.

Phhoton 

Count C 

1000 

100 

10 

Time‐resolved dynamics y at acceptor p emission 

Intensity 

PL 

0.020 

0.016 

0.012 

0008 0.008 

0.004 

• 3.4 nmol cyan-emitting NCs 

• 4.9 nmol green-emitting NCs 

I ( t) 

∝ 

kA 

25 50 75 100 

Time (ns) 

Green-emitting NCs 

Mixed cyan- and green-emitting NCs 

0 50 100 150 200 

time (ns) 

k FRET ⎛ ( k + k ) t k t 

⎜⎛ 

e 

−( 

kD 

+ k FRET ) t 

− e 

−kAt 

⎞⎟ 

⎞ 

− kD 

−k 

FRET ⎝ 

⎠

powerr 

(a.u) 

Optical O 

4 

3 

2 

1 

Color‐converted FRET‐enhanced LED 

Relativve 

optical powwer 

(a.u) 

1000 

800 

600 

400 

200 

0 

30 mA 

20 mA A 

10 mA 

540 560 580 600 620 


0 

0 10 20 30 40 50 

current (mA)

FRET LEDs 

Color converted LED FRET-enhanced color converted LED 

In our FRET-NC-LED, NCs reach a quantum efficiency level as high as 55%. 

By using a near-UV LED with an external quantum efficiency of 40%, 

this implies that it is possible to obtain color-converted color converted FRET FRET-enhanced enhanced LEDs 

with an expected external quantum efficiency of 22% and 

a predicted luminous efficiency of 94 lm/W. 


S. Nizamoglu … H.V. Demir, 

IEEE Journal of Special Topics 

Quantum Electronics 

15, 4, July/August 2009.

2 nm 

FRET‐converted light‐emitting structures

White light generating rresonant 

esonant nonradiative energy transfer 

from epitaxial InGaN InGaN/GaN GaN quantum wells to colloidal CdSe CdSe/ZnS ZnS 

core/shell core/shell quantum quantum dots 

dots 

Photon P count c 

4000 QWs+QDs 

3500 

only y QDs 

3000 

2500 

2000 

1500 

1000 

500 

0 

450 500 550 600 650 700 


The white light is generated by the luminescence of quantum wells and quantum dots, 

where the dot emission is further increased by 63% with nonradiative energy transfer, 

while setting the operating point in the white region of CIE chromaticity diagram. 

S. Nizamoglu … H.V. Demir, 

New Journal of Physics (2008).

PDDA (+) 

Layer by layer assembly of quantum dots 

Water 

CdTe 

NC (-) 

Corniing Glass (-) 

Water 

These steps are the basic 

construction sequence q for the 

simplest film architecture 

Demir Lab, Bilkent University

Architectural tuning of color chromaticity with Förster 

resonance energy ttransfer f (FRET) 

Modified donor emission Modified acceptor emission 

N. Cicek … H.V. Demir, Applied Physics Letters, 061105 (2009) 

modified emission 

kinetics 

by y controlling g FRET 

in layer layer-by by-layer layer assembled 

CdTe nanocrystals 

in collaboration 


TU Dresden

Inter 

spacing 

(MLs) 

Average decay lifetime 

(ns) 

@ 595 

nm 

donor 

emission 

@ 645 nm 

acceptor 

emission 

FRET analysis 

Total relative emission 

(eV) 

Donors Acceptors 

η 

Using PL intensities 

FRET 

= 1 

FRET efficiency (η FRET ) 

− 

F 

F 

DA 

D 

UUsing i lif lifetimes ti 

η = 1 − 

5 881 8.81 824 8.24 260 260.11 11 63 63.09 09 027 0.27 032 0.32 

3 7.41 10.63 219.69 346.02 0.39 0.43 

1 2.96 14.57 164.75 447.44 0.75 0.57 

Control 12.05 3.68 384.44 59.67 -- -- 

FRET 

τ 

τ 

DA 

D

Precise tuning of color with FRET 

Color tuning by FRET efficiency tuning 

x(η)= 0.086 η+ 0.573, 

y (η)= ‐ 0.085 η+ 0.426

Broad tuning of color with cascaded FRET 

Cascaded FRET 

with one set of starting 

power distribution 

Cascaded FRET 

including different 

power distributions 

N. Cicek et al. (2009) 

Demir Group

Ph.D. – Piled Higher and Deeper 

3/17/2010 Hilmi Volkan Demir 71

Outline 





– for spectrally enhanced lighting (high S/P ratio, high color rendering index) 









– plasmonic nanocomposites of nanophospors 

– Targeted self‐assembly of nanophosphors on LEDs using 

smart linkers 

– with specific binding 



Localized plasmons 

• Collective ll i oscillations ill i of f 

conduction band electrons 

in metal particles and 

metal structures 

– with dimensions much smaller 

th than the th wavelength l thof f optical ti l 

excitation 


Physical explanation of localized plasmons 

• Mie theory (1908): 

– complete electromagnetic 

solution 

• Quasi‐static approximation: 

– Particle size comparable to the 

penetration depth 

– E‐field is formed along the 

particle 

– Electrons are transported with E‐ 

field 

– Dipole formation 

– RRestoring i fforces 

– If restoring frequency matches 

excitation frequency => 

resonance condition 


Source: K. Sönnichsen, Plasmons in Metal Nanostructures, 

Ludwig-Maximilians University of Munich, 2001.

Physical explanation of localized plasmons (cont’d) 

• Extinction cross section of spherical metal nanoparticles 

according to Mie Theory (neglecting higher order modes) 

σ 

ext 

= 

9Vε 

3 / 

m 

c 

where V is the spherical particle volume, 

ε = + i 

2 

( ) 

[ ( ) ] ( ) 2 

ωε 2 ω 

[ 2 

εε 

( ωω 

) + 2 2εε ] + εε 

( 2 2ωω 

) 

1 

+ m 

ε i ε , ε metal 1 2 m is the dielectric constant of the 

medium,cis the speed of light in free space and ω is the angular 

frequency 


2

Use of localized plasmons 


Lycurgus cup (4th Century AD), 

British Museum

Dependence of resonance wavelength on 

different particle p and medium pproperties p 

• NNanoparticlesize ti l i => > Rd Red shift hift 

• Dielectric constant of the medium => Red shift 

Blue shift 


Red shift

Metal‐enhanced luminescence 

• Emission of materials in the close vicinity of 

metal nanoparticles, metal nanostructures or metal 

films 

QD 


Source: http://www.nanoigert.umn.edu

Plasmon‐coupled nanocrystals 

• Previous work on plasmon‐coupled emission of nanocrystals 

– Using flat films 

• emission of CdSe/ZnS nanocrystals could not be enhanced 1 

– Using gold colloids 

• emission of CdSe/ZnS nanocrystals enhanced 5 times2 emission of CdSe/ZnS nanocrystals enhanced 5 times 

– Using patterned metal nanostructures 

• emission of CdSe/ZnS nanocrystals enhanced 30‐50 times 3,4 

– Using metal island films 

• emission of CdTe nanocrystals enhanced 5 times 5 

• Previous literature focuses only on plasmon‐enhanced 

luminescence 

– However, there are other important features of luminescence 

• including emission linewidth and emission peak 

1 Ok Okamoto, K., K et al., l JJ. OOpt. Soc. S Am. A B. B 2006 2006, 23 23, no. 88. 4 SSong, JJ-H., H et t al., l NNano LLett. tt 2005 2005, 55, no. 88. 

2 Kulakovich, O., et al., Nano Lett. 2002, 2 , no. 12. 5 Ray, K., et al., J. Am. Chem. Soc. 2006, 128. 

3 Pompa, P. P., et al., Nature Nanotech. 2006, 1. 


Metal Enhanced Fluorescence

Metal Enhanced Fluorescence 

Pompa et al. Nature Nanotechnology 1, 126 ‐ 130 (2006)

Scanning electron microscope (SEM) images 

of our silver island films 

Evaporation rate: 0.1-0.2 Å/sec 

20 nm, not t annealed l d 

20 nm, annealed at 300 ºC for 10 min. 


Scanning electron microscope (SEM) images of 

our silver il il island dfil films ( (cont’d) ’d) 

6 nm, , 

annealed at 150 ºC for 1 min. 


Nanoisland formation 

AAg evaporation ti 

(0.1 A/s) on quartz 

Annealing at 300 0 Annealing at 300 C 

under N2 purge 

Nanocrystal 

integration 


Plasmon resonance tuning 

with lateral vertical dimension

Our absorbance spectra of different silver island 

fil films 

Absorbance 

(a.uu.) 

1.0 

0.8 

0.6 

0.4 

0.2 

0.0 

4 nm Ag, 300 0C, 20 min. 

2nmAg,1500 2 nm Ag, 150 C, 2 min. 

6 nm Ag, 150 0C, 2 min. 

6 nm Ag, 150 0C, 2 min.+10 nm Si O x y 

300 400 500 600 700 

Resonance wavelengths: 

426 nm 

452 nm 

488 nm 

515 nm 

Larger thickness => Red shift 

Annealing => Blue shift 

Larger dielectric constant 

at the interface => Red shift 

wavelength (nm)Tunable, controllable and reproducible 

llocalized li d plasmon l resonance bbehavior h i 


Resonance wavelengths g of our metal island films 


Interactions between plasmons p and luminescent materials 

• Physical mechanisms affecting metal‐ metal 

enhanced luminescence performance 

1. Local field enhancement close to plasmons 

2. Increased radiative recombination rate of luminescent 

material (Förster energy transfer) 

33. QQuenching hi 


Quantitative expressions of metal enhanced luminescence 

2 ( ) QYmetal = L 

Z( 

) metal 

ω 

( ) 2 

ω ( ) and 

Y ω 

exc Z 

Γ 

Γ+ 

k 

flu 

flu = 

QY 

QY 

Γ + Γ 

where and 

m 

QQY0 

= 

QYmetal 

= 

Γ + Γm 

+ 

nr 

Γ iis the h radiative di i recombination bi i rate 

Γm is the radiative recombination rate due to the presence of metal 

knr is the nonradiative decay rate 

Also, the photon lifetime decreases by the factor 


F 

P 

0 

k 

nr 

Γ + k nr + Γ 

= 

Γ + k 

nr 

m

Spectral design of plasmon‐coupled nanocrystals 

• Resonance wavelength 

matching 

0 

• λ(Ag)=457 nm 

λ(Ag+SixOy)=476 nm 

λ(Emission)=493 nm 

0.8 

• Red shift with the 

addition of nanocrystals y 

0.6 

taken into account 

0.4 

• Nanoisland size: avoided 

very small nanoislands 

(

Structural design of plasmon‐coupled nanocrystals 

Quenching: effective in 5 nm 

Increased field: effective in 15 nm 

Increased decay rate: effective in 25 nm 

Distance < 5 nm => quenching 

Di Distance t > 20 nm=> > almost l t iisolated l t d 

J. R. Lakowicz, “Radiative decay engineering: biophysical 

and biomedical applications,” Anal. Biochem., vol. 298, 2001, pp. 1-24. 


Photoluminnescence 

(couunts) 

30000 

25000 

20000 

15000 

10000 

5000 

Localized plasmon coupled nanocrystal 

emitters 

NC+Si O +nanoAg 

x y 

control NC 

1.0 

control t l NC+nanoAg 

NC A 08 0.8 

NC+Si x O y +nanoAg: NC: NC+nanoAg 

15.1:1.0: 0.7 

0 

400 450 500 550 600 650 700 


Normalized photolumines 

p scence 

0.6 

04 0.4 

0.2 

492 nm 506 nm 

NC+Si x O y +nanoAg 

control t l NC 

NC NC+Si O +nanoAg 

x y 

λ : 492 nm 

PL 

FWHM: 45 nm 

506 nm 

35 nm 

00 0.0 

400 450 500 550 600 650 700 


CdSe CdSe/ZnS ZnS nanocrystals closely closely-packed packed in the proximity of Ag nanoisland films: 

1) 1)enhancing 1.) enhancing the PL intensity by 15 15.1 1 times compared to the same nanocrystals 

without nano-Ag nano Ag (no plasmonic resonance) 

and 21.6 times on the average compared to the same nanocrystals with nano-Ag nano Ag 

but no dielectric spacer (when quenched) 

2.) shifting peak emission wavelength (by 14 nm) and 

3.) reducing emission linewidth (by 10 nm FWHM, corresponding to >22 %) 


I. M. Soganci, S. Nizamoglu, E. Mutlugun and H. V. Demir, Optics Express 15(22), 14289 (2007).

Plasmon coupled surface state emitting nanocrystals 


Surface‐state emission is 

8.9 weaker than the 

bband‐edge d d emission. i i 

Plasmon resonance tuned 

to match the peak surface state emission: 

Vertical film thickness: 10 nm 

Lateral size distribution: 25‐75 nm

Material 

on quartz 

substrate 

Only SSE 

NC 

SSE NC 

with 10 nm 

Ag 

Selectively y plasmon p enhanced surface state emission 

Band-edge 

emission 

λ 1 (nm) 

Surface-state 

emission 

λ 2 (nm) 

λ 1 peak 

intensity 

(counts) 

λ 2 peak 

intensity 

(counts) 

Intensity 

ratio 

@λ 2 / 

@λ 1 

Highlighted in 

Introduction to Nanophotonics 

by Sergey V. Gaponenko, 

Cambridge University Press 

(2009) 

EEnhancement h tiin th the ratio ti of f 

surface‐state peak emission to 

band‐edge peak emission of 

plasmon‐coupled p p film sample p 

compared to that in solution: 

12.7 folds 

Total 

number of 

photons 

415 545 1388 290 0.21 67,885 , T. Ozel, I. M. Soganci, S. Nizamoglu, I. 

O. Huyal, E. Mutlugun, S. 

415 531 672 960 1.43 122,055 

Sapra, N. Gaponik, A. Eychmüller, 

H. V. Demir, New Journal of Physics 


10, 083035 (2008).

Outline 















How can we combat climate change 

using NANOPHOTONICS? 


consumption? 

– Light generation 

• Solid state lighting using nanophosphors 

– for the generation of high‐quality white light 

– using nonradiative energy transfer 

• Can we help to convert solar energy more 

efficiently? 

– Light harvesting 

• Quantum dot integrated solar cells 

– for the extension of spectral response 

– also using nonradiative energy transfer 

• C Can we help h l t to reduce d the th amount t of f 


– Photocatalytic nanoparticle integrated systems 

• ffor massive i environmental i t ld decontamination 

t i ti 


GREEN 

NANOPHOTONICS 

current (mA) 

*2 patents pending 

voltage (V) 

0 

0 02 0.2 04 0.4 06 0.6 08 0.8 1 12 1.2 14 1.4 16 1.6 18 1.8 2 

-2 

-4 

-6 

-8 

PL Intensity (a.u.) 

*1 patent p 

* 3 patents 

350 400 450 500 550 600 650 700 

λ (nm) 

wihout nanocrystals 


with 10.40 nanomol/cm2 nanocrystals y 



with 67.60 nanomol/cm2 nanocrystals

Flashback – in 2005 

• Future perspective: We proposed and envisioned that these 

p p p p 

hybrid nanphosphor white LEDs are promising candidates for future 

solid-state lighting applications.

Today – in 2010 

• Nanocrystal based light emitting diodes are 

commercially y available today. y 

• However, high‐quality nanophosphor LEDs 

are not commercialized yet.

Single to few nanoparticle devices 

• Our on‐chip integration from macro to micro to nano scale: 

15 mm 

CC. UUran, EE. UUnal, l RR. Ki Kizil, il and d HH. VV. 

Demir, IEEE Journal of Selected Topics in 

Quantum Electronics Vol. 15, 5, 2009 

Fully integrated chip with macroprobes 


Microfabricated electrode array 

20 nm 

Aligned and clamped 

nanowires 

Captured 

nanoparticles

Conclusions 

• Climate change is a major problem. Solid state lighting potentially offers 

substantial reduction in energy consumption and greenhouse gas 

emission. 

• Nanocrystal emitters outperform conventional phoshors in white light 

generation in certain optical aspects with 

• warm color temperature and high color rendering index 

– for day vision (indoors applications) 

• tuneable operating point (tuned tristimulus coordinates) 

– for application‐specific spectral illumination (niche applications) 

• Nanocrystall LEDs bbenefit fi ffrom 

– nonradiative energy transfer between nanocrystals 

– nonradiative energy transfer from epitaxial quantum wells to nanocrystals 

– plasmon coupling 

• Nanostructured white LEDs of nanocrystal emitters hold promise for high 

quality lighting. 


Bilkent Devices and Sensors Group 

• Dr. Nihan Kosku Pekgöz (project coordinator) 

• Dr. Olga Samarska (postdoctoral fellow) 

• Dr. Mehmet Şahin Ş (visiting ( g scholar) ) 

• R. Eng. Özgün Akyüz (lab manager engineer) 

• R. Eng. Müh. Emre Ünal (technıcal learder engıneer) 

• Rohat Melik (phd) 

• Evren Mutlugün (phd) 

• Sedat Nizamoğlu (phd) 

• Emre Sarı (phd) 

• Can Uran (phd) 

• Gulis Zengin (phd) 

• Aslı Ünlügedik (phd) 

• Akın Sefunç (phd) 

• Neslihan Çiçek (ms‐phd) 

• Onur Akın (ms‐phd) 

• Gürkan Polat (ms‐phd) 

• Tuncay Özel (ms) 

• Ilkem Özge Huyal (ms) 

• Sina Toru Refik (ms) 

• Talha Erdem (ms) 

• Burak Güzeltürk (ms) 

Previous members 

• Dr. Gülşah Yaman (postdoc) 

• Dr. Yang Zhang (postdoc) 

• Eng..Aslı Koç (research engıneer) 

• İbrahim Murat Soğancı (ms) 

• Sümeyra Tek (ms) 

• Mustafa Yorulmaz (ug) 

Acknowledgements 

Collaborators: 

• TU Dresden (N. Gaponik, S. Sapra, S. Hickey, 

A. Eychmüller) y ) 

• Belarus National Academy of Science (S. Gaponenko, M. 

Artemyev) 

• KOPTI (I. Lee, J. Baek) 

• NTU (XW Sun, K. Pita) 

Funding and support: 

• ESF EURYI 

• EU Nanophotonics4Energy 

• EU MOON 021391 

• ESF COST MP0701 

• NIH 5R01EB010035-02 

• KRF- TUBITAK 1070297 

• NASB - TUBITAK 107E088 

• BMBF-TUBITAK 109E002 

• T UBITAK 106E020 

• INNOVNANO 

• NRF RF 2009-09 


Device and Sensors Group 

Demir lab 2008-2009 SCI Publications: 

1. Applied Physics Letters 92, 031102 (2008). 


3. New Journal of Physics y 16(2), ( ), 1115 (2008). ( ) 

4. Optics Express 16(6), 3515 (2008). 


6. Optics Express 16(6), 3537 (2008). 

7. J. Materials Chemistry 18, 3568-3574 (2008). Demir lab 2008-2009 

8. Optics Express 10, 023026 (2008). 

Patent Applications: 

99. EEuropean FFebs b JJournal l 275 275, 97 (2008) (2008). 

1. Zizgag InGaN quantum 

10. Nanotechnology 19, 335203 (2008). 

11. New Journal of Physics 10, 083035 (2008). 

modulators, pending. 

12. Optics Express 16, 13391-13397 (2008). 

2. LED-MOD-Detector diodes, pending. 

13. IEEE Trans. Electron Devices 55, 3459-3466(2008). 3. Photovoltaic nanocrystal 

14 14. JJ. Micromech Micromech. Microengineering 18 18, 115017 (2008) (2008). scintillators scintillators, pending pending. 

15. Optics Express 16, 13961-13968 (2008). 

4. PFA white emitters, pending. 

16. New Journal of Physics 10, 123001 (2008). 

5. High s/p solid state lighting, pending. 

17.Applied Physics Letters 95, 011106 (2009). 

6. Nanophosphors efficiency 


enhancement, pending. 

19. IEEE JSTQE , 15 4), ) 1163 (2009). ( ) 

77. Bilkent DYO photocatalytic 

20. Journal of Applied Physics106, 043704 (2009) 

synergy, pending. 

21. Applied Physics Letters 94, 061105(2009) 

8. Bilkent DYO Arçelik photocatalytic 

22. Journal of Applied Physics 105, 083112(2009) 

nanocomposite, pending. 

23. IEEE Journal of Special Topics in Quantum 

Electronics15, 5, 1413 (2009). 

9. Bilkent Innovnano 

24 24. AApplied li d Ph Physics i Letters L tt 94 94, 211107 (2009) 

composite composite, pending. pending 

25. Applied Physics Letters 94, 243107 (2009) 

10. Bilkent Synthese 

26. Applied Physics Letters (in press) 

bioimplant, pending. 

27. IEEE Journal of Special 

Hilmi 

Topics 

Volkan 

in Quantum 

Demir 

Electronics (special issue on Metamaterials) (in press).

Our research program 

• High‐quality light emitting diodes (LEDs) 

– Nanocrystal y hybridized y white LEDs ( (NC‐LED) ) 

– Nonradiative energy transfer converted white LEDs (FRET‐LED) Plasmonically 

enhanced white LEDs (plasmon‐LED) 

– High‐brightness LEDs (InGaN/GaN HB‐LED) 

– Nanostructured LEDS (nano‐LED) 

• High High‐efficiency efficiency photovoltaic devices (PV) 

– Nanocrystal integrated photovoltaic devices (NC‐PV) 

– Plasmonically enhanced photovoltaic devices (plasmon‐PV) 

– Nanowire photovoltaic devices (NW‐PV) 

• Nanocrystal Nanocrystal, metal nanoparticle and nanowire embedded devices 

and systems 

– Field‐assisted self‐assembly (dielectorphoresis) 

– On‐chip integrated nanowire device platform 

– Single g nano‐particle p devices 

– Photocatalytic nanocomposite systems 

• Quantum modulators / Photonic switches 

– Visible quantum electroabsorption modulators (InGaN) 

– UV quantum electroabsorption modulators(InAlGaN) 

– Quantum dot luminescence modulators/photonic switches 

– Nanorod modulators 


Our research program 

• Biomimetic optoelectronic devices 

– Peptide decorated nanocrystal emitters. 

– Targeted self‐assembly of nanocrystals/nanoparticles 

/ 

– Layer‐by‐Layer templated nanocrystals using biomineralization 

– Nanohybrids assembled with genetically engineered peptides 

• Innovative RF and optoelectronic sensors 

– CCompact thi high‐Q h Q RF rezonators t 

– Wireless RF‐MEMS sensors 

– Bioimplant sensors 

• Novel nanophotonic devices 

– Polymer nanoparticles 

– Organic nanodevices 

– Novel nano‐device fabrication 

• Physics and applications of nano‐structures 

– Quantum structure modeling 

– Local plasmon modeling 

– FRET modeling 

– Modification of photoluminescence kinetics (modified time‐ 

resolved fluorescence, modified lifetime) 

– RF characterization h t i ti of f nanostructure t t assemblies 

bli 


Thanks… 


…. towards sustainable Earth 

semiconductor lighting for energy efficiency … 


“Let our light shine!”

Hilmi Volkan Demir - KTH

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