University of Groningen
Colloidal quantum dot solids
Balázs, Dániel Máté
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Publication date: 2018
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Balázs, D. M. (2018). Colloidal quantum dot solids: Nanoscale control of the electronic properties. University of Groningen.
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Colloidal Quantum Dot Solids
Nanoscale control of the electronic properties
Zernike Institute PhD thesis series 2018-3 ISSN: 1570-1530
ISBN: 978-94-034-0365-6 (print version) ISBN: 978-94-034-0364-9 (electronic version)
The work in this thesis was performed in the Photophysics and OptoElectronics group of the Zernike Institute for Advanced Materials at the University of
Groningen in The Netherlands. The research was funded by the European Research Council through the ERC Starting Grant No. 306983 (HySPOD). Reuse of any materials published in this thesis is only permitted following the copyright license of the publication mentioned on the corresponding chapter title page.
Cover design: Rebeka Balazs M.A. The pattern is an abstract representation of the superlattice of rhombicuboctahedra, the structure observed in Chapters 3,5 and 6.
Printed by Gildeprint
Colloidal Quantum Dot Solids
Nanoscale control of the electronic properties
PhD thesis
to obtain degree of PhD at the University of Groningen
on the authority of the Rector Magnificus Prof. E. Sterken
and in accordance with the decision by the College of Deans. This thesis will be defended in public on Friday 16 February 2018 at 16:15 hours.
by
Dániel Máté Balázs
born on 1June 1989 in Budapest, Hungary
Supervisor
Prof. M. A. Loi
Co-supervisor
Prof. M. V. Kovalenko
Assessment committee
Prof. B. Noheda Pinuaga Prof. A. Facchetti Prof. T. Hanrath
Table of contents
1. Introduction to colloidal quantum dot solids ... 3
1.1. Solution-processed semiconductors ... 4
1.2. Colloidal quantum dots ... 5
1.3. Quantum dots in proximity ... 8
1.4. Surface-based property control ... 11
1.5. Characterization methods for novel semiconductors ... 13
1.6. Outline of the thesis ... 18
1.7. References ... 19
2. Reducing charge trapping in PbS colloidal quantum dot solids ... 23
2.1. Introduction ... 24
2.2. General characteristics of the PbS FETs ... 25
2.3. Effect of ambient conditions ... 26
2.4. Conclusion ... 30
2.5. Experimental methods ... 31
2.6. References ... 32
3. Counterion-mediated ligand exchange for PbS colloidal quantum dot superlattices ... 33
3.1. Introduction ... 34
3.2. Nanostructure: influence of the counterions and epitaxial fusion ... 35
3.3. Optical properties ... 38
3.4. Transport properties determined by the ligand exchange conditions ... 40
3.5. Catalytic mechanism of the ligand exchange process ... 44
3.6. Conclusions ... 47
3.7. Experimental methods ... 48
4. Colloidal quantum dot inks for single-step-fabricated
field-effect transistors ... 53
4.1. Introduction ... 54
4.2. Ink formation and properties ... 54
4.3. Ink-based FETs ... 57
4.4. Effect of post-deposition washing... 59
4.5. Conclusion ... 63
4.6. Experimental methods ... 63
4.7. References ... 65
4.8. Appendix ... 67
5. Stoichiometric control of the density of states in PbS colloidal quantum dot solids ... 69
5.1. Introduction ... 70
5.2. Chemically controlled stoichiometry in PbS CQD solids ... 71
5.3. Stoichiometry-dependent transport properties ... 75
5.4. Electrolyte-gated transport properties ... 77
5.5. Evaluation of the results... 79
5.6. Conclusions ... 80
5.7. Experimental Methods ... 81
5.8. References ... 85
6. Electron mobility above 24 cm2 /Vs in PbSe colloidal quantum dot superlattices ... 87
6.1. Introduction ... 88
6.2. Nanostructure of PbSe CQD superlattices ... 89
6.3. Electrical transport in PbSe CQD superlattice FETs ... 95
6.4. Conclusions ... 100 6.5. Experimental methods ... 100 6.6. References ... 104 6.7. Appendix ... 106 Summary ... 109 Samenvatting ... 111
