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How the Polaronic Nature of Perovskite Nanocrystals Determines Multiexciton Properties.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	How the Polaronic Nature of Perovskite Nanocrystals Determines Multiexciton Properties./
Author:	Strandell, Dallas Paul.
Description:	1 online resource (203 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-05, Section: B.
Contained By:	Dissertations Abstracts International85-05B.
Subject:	Metals. -
Online resource:	click for full text (PQDT)
ISBN:	9798380705752

How the Polaronic Nature of Perovskite Nanocrystals Determines Multiexciton Properties.
Strandell, Dallas Paul.

How the Polaronic Nature of Perovskite Nanocrystals Determines Multiexciton Properties. - 1 online resource (203 pages)

Source: Dissertations Abstracts International, Volume: 85-05, Section: B.

Thesis (Ph.D.)--McGill University (Canada), 2023.

Includes bibliographical references

Perovskite nanocrystals are a new class of material that have drawn much interest for their high intrinsic photoluminescence quantum yields and simple syntheses. These APbX3 nanocrystals are able to span the visible spectrum through halide composition: chloride emit blue while bromide and iodide emit green and red respectively. The green emitting APbBr3 in particular have been focused on due to higher stabilities relative to the chloride and iodide species. Research into the properties of CsPbBr3 has highlighted the polaronic nature as having a large effect on the electronic properties. The highly polar lattice of CsPbBr3 causes the polaron to have this large impact. This contrasts the traditional II-VI and III-V semiconductor nanocrystals, such as CdSe, which have covalently dominated bonding.This thesis summarises my work on the emissive properties of CsPbBr3 nanocrystals. The first section focuses on the temperature dependent photoluminescence and how the nanocrystals used are bulk-like and not quantum confined (>10nm in edge length). This was done through Franck-Condon modeling which showed the photoluminescence was dominated by homogeneous broadening. This was vital for future work demonstrating that the polaron that forms around the exciton contributes to confining the exciton.The second and third sections contain time resolved photoluminescence with high time resolution (3ps). The fitting of time resolved multi-excitonic spectra is the focus of the second section. Unconfined semiconductors should show little evidence of multiexcitons in the photoluminescence spectra. Therefore, polaronic confinement of excitons was invoked to account for the confinement effects in a spatially unconfined nanocrystal. The third section was an extension of the second project with temperature dependence. With a focus on the fast multiexciton emission, the decay rates an quantum yields were calculated. The multiexciton emission was found to slow down and increase in brightness at low temperatures. This is the first report of the temperature dependence of Auger rates in perovskite nanocrystals.The fourth section is a combination of analysis done in the previous three sections. With high time resolution and temperature dependence, the linewidth kinetics of the exciton was shown. This time dependence revealed fine structure of the exciton. The addition of a second exciton state allows additional Frank-Condon analysis to reveal the full linewidth temperature dependence. Additionally, Auger heating is shown using high fluences at 4K. As multiexcitons nonradiatively recombine, The lattice is heated which caused linewidth broadening.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798380705752Subjects--Topical Terms:

563369
Metals.
Index Terms--Genre/Form:

554714
Electronic books.

How the Polaronic Nature of Perovskite Nanocrystals Determines Multiexciton Properties.
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502 $a Thesis (Ph.D.)--McGill University (Canada), 2023.
504 $a Includes bibliographical references
520 $a Perovskite nanocrystals are a new class of material that have drawn much interest for their high intrinsic photoluminescence quantum yields and simple syntheses. These APbX3 nanocrystals are able to span the visible spectrum through halide composition: chloride emit blue while bromide and iodide emit green and red respectively. The green emitting APbBr3 in particular have been focused on due to higher stabilities relative to the chloride and iodide species. Research into the properties of CsPbBr3 has highlighted the polaronic nature as having a large effect on the electronic properties. The highly polar lattice of CsPbBr3 causes the polaron to have this large impact. This contrasts the traditional II-VI and III-V semiconductor nanocrystals, such as CdSe, which have covalently dominated bonding.This thesis summarises my work on the emissive properties of CsPbBr3 nanocrystals. The first section focuses on the temperature dependent photoluminescence and how the nanocrystals used are bulk-like and not quantum confined (>10nm in edge length). This was done through Franck-Condon modeling which showed the photoluminescence was dominated by homogeneous broadening. This was vital for future work demonstrating that the polaron that forms around the exciton contributes to confining the exciton.The second and third sections contain time resolved photoluminescence with high time resolution (3ps). The fitting of time resolved multi-excitonic spectra is the focus of the second section. Unconfined semiconductors should show little evidence of multiexcitons in the photoluminescence spectra. Therefore, polaronic confinement of excitons was invoked to account for the confinement effects in a spatially unconfined nanocrystal. The third section was an extension of the second project with temperature dependence. With a focus on the fast multiexciton emission, the decay rates an quantum yields were calculated. The multiexciton emission was found to slow down and increase in brightness at low temperatures. This is the first report of the temperature dependence of Auger rates in perovskite nanocrystals.The fourth section is a combination of analysis done in the previous three sections. With high time resolution and temperature dependence, the linewidth kinetics of the exciton was shown. This time dependence revealed fine structure of the exciton. The addition of a second exciton state allows additional Frank-Condon analysis to reveal the full linewidth temperature dependence. Additionally, Auger heating is shown using high fluences at 4K. As multiexcitons nonradiatively recombine, The lattice is heated which caused linewidth broadening.
520 $a Les nanocistaux de perovekile consfluem une nouvele calegorie de maberiaux qui ont suscibe un grand inter&t en raison de leurs rendements quantiques eleves de photoluminescence intinseque et de leur simpliche de synihise. LAPbEY,, qui emas dar le vert, a fait Fobjet Sune attention particulitre en raison de sa plus grande stabilita par rappori aux espices chiorure et iodure. La recherche sur les propriates du CaPbBr; a mis en evidence la nabure potaire qui a un effet important sur les propridtes lectroniques. Le reseau hantement potaire du CsFoBr, permet au polaron davoir un impact important. Ceia contraste avec les nanocrstaus semi-conducieurs E-VI et II-V traditionneis, teis que le CdSe. dont la Raison est domines par la covalence.Ceite lhise retume mon bravail sur les proprietes emissives des nanocrstaux de CsPbBs. La premibre secton se concentre sur ia phololuminescence dependante de ta temperaturs es sur la facon dont les nanocristsur que [ai synihetises sont en vrac es non contints quantiquement (-- 10r1m en longueur de bord). Cela a eie tai grace a la modeiisation de Franck-Condon qui a montre que la photoluminescence etal dominte par un elangssement homogene. Ce resukat etait essentiel pour les luturs lravauz de notre groupe. qui montrent que le polaren qui se forme autour de lesciton confibue a continer Feciton.Les deuxieme e toisieme sections coniennent la photoluminescence resoue en lemps avec me hate resoluian temporele (4ps). Uajusiemen des spectres mult-enctoniques resolus en temps est le poini central de la deuxikme section. Les semi-conducteurs non conlinas devraiens mantrer peu de signes de muliencions dans les spectres de photoluminescence. Par consaquent, le confinemem potararique des excitons a ete invoque pour expliquer les eflets de conlinement dans un nanocristal spatialement nen conine. La troisieme section etail une extension du deuxieme projet avec ia dependiance de Ia lemperaiure. En se concentrant sur remission rapide des multencions, les tau de dacroissance et les rendements quarntiques ont &e calcules. On a constale que Femiesion meullienciton raleniil et augmente en brilance a basse temperature. E s'aga du premier rapport sur la dependance en lemperature de [emission Auger dans les nanocristai de parovkie.La quairieme section est une combinaison des ansiyses eMectudes dans les trois sections precedertes. Avec une hauls regoluson lemporeile et une dependance & ta temperature, ia cinetique de la largeu de ligne de I'exciton a ete moranie. Cette dependance temporsae a reveis la esructure fine de encon. Lajout Sun deuxiame dest excion permes une analyse Frank-Condon supplementaire pour reveler la dependance de la temperalure de ta large de gre complite De plus. ie chauliage Auger est monire en ulilisant des luences eievees a 4K. Comme les multiencions se recombinen de manitre non radiaive, le reseau est chautie, ce qui entrane un Elargissemen de a targeur de ligne.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2024
538 $a Mode of access: World Wide Web
650 4 $a Metals. $3 563369
650 4 $a Electrons. $3 580456
650 4 $a Semiconductors. $3 578843
650 4 $a Light emitting diodes. $3 639549
650 4 $a Phase transitions. $3 1464712
650 4 $a Nanocrystals. $3 565448
650 4 $a Energy. $3 784773
650 4 $a Quantum dots. $3 574252
650 4 $a Optics. $3 595336
650 4 $a Atomic physics. $3 1182532
650 4 $a Electrical engineering. $3 596380
650 4 $a Engineering. $3 561152
650 4 $a Physics. $3 564049
650 4 $a Quantum physics. $3 1179090
655 7 $a Electronic books. $2 local $3 554714
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