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Niklas Cordes Supervisor: Askhat N. Jumabekov. Solid-state Quantum Dot Sensitized Solar Cells and Their Electron Lifetime Studies. 17.12.2013. Content. Introduction Lead sulfide quantum dots S olid-state quantum dot sensitized solar cells Results

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Niklas Cordes Supervisor: Askhat N. Jumabekov

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Niklas cordes supervisor askhat n jumabekov

Niklas Cordes

Supervisor: Askhat N. Jumabekov

Solid-state Quantum Dot Sensitized Solar Cells and Their Electron Lifetime Studies

17.12.2013


Niklas cordes supervisor askhat n jumabekov

Content

  • Introduction

    • Lead sulfide quantum dots

    • Solid-state quantum dot sensitized solar cells

  • Results

    • Fabrication and characterization of PbSss-QDSSC

  • Conclusions and outlook

Niklas Cordes, 17.12.2013

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Niklas cordes supervisor askhat n jumabekov

Introduction

Introduction

  • QDs on wide-bandgap semiconductor nanocrystals

  • sunlight  exciton

  • e- into conduction band

  • QD is restored by electrolyte

  • regeneration on counter electrode

  • circuit completed via electron migration through external load

  •  electrical power when irradiated with sunlight

Z. Yang et al. Chem. Commun., 2011, 47, 9561-9571.

Niklas Cordes, 17.12.2013

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Niklas cordes supervisor askhat n jumabekov

Motivations and Aims

  • Motivation

  • liquid electrolytes causing photo-corrosion and leakage

    • reduce cell lifetime

  • ss-QDSSC cheap and easy to produce

  • QD properties: overcome Schockley-Queisser limit, MEG

  • Aims

  • prevention of oxide layer of the surface of PbS-QDs

  • decrease electronic trape states via surface modification

  • decrease electron hole recombination with GSH

  • remove midgaptrapes

  • understand electronic processes

    • get better efficiency

J. Nozik, Nano Letters, 2010, 10, 2735-2741

J. Tang, E. H. Sargent, Adv. Mater. 2011, 23, 12–29

Niklas Cordes, 17.12.2013

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Niklas cordes supervisor askhat n jumabekov

Aims

PbS QD

PbS QD

e-

e-

CB

CB

CB

Redox

Redox

VB

TiO2

VB

TiO2

h+

h+

Test

 surfacemodificationby GSH molecules

Reference

l-glutathione(GSH)

Niklas Cordes, 17.12.2013

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Niklas cordes supervisor askhat n jumabekov

Results

IV measurements and EQE measurements

Niklas Cordes, 17.12.2013

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Niklas cordes supervisor askhat n jumabekov

Results

UV Vis measurements

 Higher absorbancefortestcell

Niklas Cordes, 17.12.2013

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Niklas cordes supervisor askhat n jumabekov

Results

OCVD measurements

Voltage (V)

time (s)

 higher lifetime for test cell at lower voltage

Niklas Cordes, 17.12.2013

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Niklas cordes supervisor askhat n jumabekov

Results

REM

a: counter electrode (Ag)

b: TiO2 with PbS-QD (not resoluted)

c: Polymer

d: blocking layer

e: FTO

f: glass

XRD

TiO2-anatase phase

a

b

c

d

e

f

Niklas Cordes, 17.12.2013

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Niklas cordes supervisor askhat n jumabekov

Conclusions and outlook

  • Conclusions

    • Fabrication and characterization of ss-QDSSC

    • Better performance with surface modification via GSH

  • Outlook

    • screening other molecules

    • combine different molecules

NiklasCordes, 17.12.2013

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Niklas cordes supervisor askhat n jumabekov

Acknowledgments

Thanks to:

Prof. Dr. Thomas Bein

Askhat N. Jumabekov

Tina Reuther

Dr. Steffen Schmidt

Thank you all for your attention!!!

Niklas Cordes, 17.12.2013

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