Photophysics of Perovskite Nano- and Microcrystals

Junsheng Chen

Photophysics of Perovskite Nano- and Microcrystals

Junsheng Chen

Forskningsoutput: Avhandling › Doktorsavhandling (sammanläggning)

795 Nedladdningar (Pure)

Sammanfattning

Varje år ökar världens energiförbrukning på grund av befolkningstillväxt och ökande levnadsstandard. Vi står inför många stora problem, till exempel klimatförändringar, uttömning av fossila energikällor (t. ex. petroleum, kol och naturgas) och miljöföroreningar. Därför är det brådskande att söka efter förnyelsebar energi och hur människor kan använda energi så effektivt och ändamålsenligt som möjligt. Högeffektiva material är viktiga för att utvinna och använda energi ändamålsenligt. Under de senaste åren har blyhalogenidperovskitmaterial blivit en typ av lovande och mångsidiga material avsedda för förnyelsebar energiproduktion, till exempel solceller. Blyhalogenidperovskitmaterial kan användas för att tillverka effektivare energiomvandlingsprodukter för vardagsbruk, t.ex. ljussättning (t.ex. lysdioder, LED:er), bildskärmar (t.ex. teveapparater), fotodetektorer (t.ex. kameror) och lasrar. Det finns absorption och emission av fotoner i alla produkterna. Under fotonabsorption och -emission sker många fotofysiska processer.
Omfattande kunskaper om blyhalogenidperovskitmaterialens fotofysik kommer att spela en viktig roll för att förbättra både materialens och produkternas funktion. I den här avhandlingen utforskade vi fotofysiken i perovskitkristaller av nanostorlek (1 nm = 0,000 000 001 m) och mikrostorlek (1 μm = 0,000 001 m) som kanske kan användas för LED:er, TV-apparater och fotodetektorer. Vi utforskade
blyhalogenidperovskitnanokristallers stabilitet under ljusbestrålning.
Blyhalogenidperovskitnanokristaller kan bli ett aktivt medium för lasrar med tvåfotonabsorption (där två fotoner absorberas samtidigt). Därför utforskade vi tvåfotonabsorptionsprocessen i blyhalogenidperovskitnanokristaller. Sedan tillverkade vi en högeffektiv fotodetektor baserad på blyhalogenidperovskitmikrokristallager.
Det finns stora miljöproblem med att använda blyhalogenidperovskitmaterial som innehåller giftigt bly. Därför ersatte vi det giftiga blyet med mindre giftig vismut i perovskitnanokristaller. De vismutbaserade kristallerna fotoluminescerar med synligt ljus. Emissionsintensiteten är dock väldigt svag på grund av att laddningsbärare fastnar i fälltillstånd. Det är möjligt att begränsa fällorna och öka emissionsintensiteten för användning i LED:er.

Originalspråk	engelska
Kvalifikation	Doktor
Tilldelande institution	Lunds universitet
Handledare	Pullerits, Tönu, handledare
Tilldelningsdatum	2018 mars 16
Utgivningsort	Lund
Förlag	Lund University, Faculty of Science, Department of Chemistry, Division of Chemical Physics
ISBN (tryckt)	978-91-7422-567-9
ISBN (elektroniskt)	978-91-7422-568-6
Status	Published - 2018 feb.

Bibliografisk information

Defence details
Date: 2018-03-16
Time: 13:15
Place: Lecture hall F, Center for chemistry and chemical engineering, Naturvetarvägen 14, Lund
External reviewer(s)
Name: Lian, Tianquan
Title: Prof. Dr.
Affiliation: Department of Chemistry, Emory University, Atlanta, USA
---

Ämnesklassifikation (UKÄ)

Fysikalisk kemi
Materialkemi
Den kondenserade materiens fysik
Atom- och molekylfysik och optik
Nanoteknik

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Thesis_Junsheng_for_nailing_MaintextPublicerad version, 6,11 MBLicens: Ospecificerad

5 Artikel i vetenskaplig tidskrift

Enhanced Size Selection in Two-Photon Excitation for CsPbBr₃ Perovskite Nanocrystals
Chen, J., Chábera, P., Pascher, T., Messing, M. E., Schaller, R., Canton, S., Zheng, K. & Pullerits, T., 2017 okt. 19, I: Journal of Physical Chemistry Letters. 8, 20, s. 5119-5124 6 s.
Forskningsoutput: Tidskriftsbidrag › Artikel i vetenskaplig tidskrift › Peer review
Ultrasensitive and Fast All-Inorganic Perovskite-Based Photodetector via Fast Carrier Diffusion
Yang, B., Zhang, F., Chen, J., Yang, S., Xia, X., Pullerits, T., Deng, W. & Han, K., 2017 okt., I: Advanced Materials. 29, 40, s. 1703758
Forskningsoutput: Tidskriftsbidrag › Artikel i vetenskaplig tidskrift › Peer review
Size-And Wavelength-Dependent Two-Photon Absorption Cross-Section of CsPbBr₃ Perovskite Quantum Dots
Chen, J., Zidek, K., Chábera, P., Liu, D., Cheng, P., Nuuttila, L., Al-Marri, M. J., Lehtivuori, H., Messing, M. E., Han, K., Zheng, K. & Pullerits, T., 2017 maj 18, I: Journal of Physical Chemistry Letters. 8, 10, s. 2316-2321 6 s.
Forskningsoutput: Tidskriftsbidrag › Artikel i vetenskaplig tidskrift › Peer review

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title = "Photophysics of Perovskite Nano- and Microcrystals",

abstract = "The demand and consumption of energy is increasing dramatically all around the world. Broad adoption of fossil fuels has triggered an enormous threat to the environment. To ensure sustainability of our species and habitat, new solutions to fulfill the energy demand have to be found. Innovative materials offer the possibility to generate scalable renewable energy, which is efficient and environmentally friendly. In recent years, it was demonstrated that lead halide perovskite (LHP) materials prepared with superior optoelectronic properties which are desirable for solar-cell applications. Moreover, the solution processing ensures cheap production of those materials. In order to optimize and widely adopt LHPs as a key component for solar energy generators, it is important to understand the fundamental photophysical processes governing their unique behavior. In this thesis we studied the photophysics of LHP nano- (NC) and microcrystals (MC) using spectroscopic methods. We investigated the photostability of NCs, and found the light irradiation induced particle aggregation. Furthermore, we revealed large two-photon absorption cross sections of these NCs, and we conclude that the two-photon absorption process populates the exciton band through a virtual state. Moreover, we have demonstrated the crucial role of size distribution in explaining the difference between the one-photon excited and two-photon excited photoluminescence (PL).We fabricated photodetectors using micrometer-sized LHP crystals as building blocks, which show high responsivity as well as fast response in both the visible (one-photon absorption process) and the near infrared (NIR) region (two-photon absorption process). We also elucidated the underlying mechanism for the enhanced photoresponse by efficient charge collection, low trap density and high charge carrier mobility in the MCs.In order to develop environmentally friendly materials, we replaced the lead element with less toxic bismuth in LHP structures to form the bismuth-based perovskite NCs, which exhibit tunable PL but with low quantum yield. The photophysical studies in such NCs with time-resolved spectroscopy attributed the low PL emission intensity to a fast trapping process.",

keywords = "Ultrafast spectroscopy, Two-photon absorption, Perovskite, Nanocrystals, Photostability, Lead free perovskite",

author = "Junsheng Chen",

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AU - Chen, Junsheng

N1 - Defence details Date: 2018-03-16 Time: 13:15 Place: Lecture hall F, Center for chemistry and chemical engineering, Naturvetarvägen 14, Lund External reviewer(s) Name: Lian, Tianquan Title: Prof. Dr. Affiliation: Department of Chemistry, Emory University, Atlanta, USA ---

PY - 2018/2

Y1 - 2018/2

N2 - The demand and consumption of energy is increasing dramatically all around the world. Broad adoption of fossil fuels has triggered an enormous threat to the environment. To ensure sustainability of our species and habitat, new solutions to fulfill the energy demand have to be found. Innovative materials offer the possibility to generate scalable renewable energy, which is efficient and environmentally friendly. In recent years, it was demonstrated that lead halide perovskite (LHP) materials prepared with superior optoelectronic properties which are desirable for solar-cell applications. Moreover, the solution processing ensures cheap production of those materials. In order to optimize and widely adopt LHPs as a key component for solar energy generators, it is important to understand the fundamental photophysical processes governing their unique behavior. In this thesis we studied the photophysics of LHP nano- (NC) and microcrystals (MC) using spectroscopic methods. We investigated the photostability of NCs, and found the light irradiation induced particle aggregation. Furthermore, we revealed large two-photon absorption cross sections of these NCs, and we conclude that the two-photon absorption process populates the exciton band through a virtual state. Moreover, we have demonstrated the crucial role of size distribution in explaining the difference between the one-photon excited and two-photon excited photoluminescence (PL).We fabricated photodetectors using micrometer-sized LHP crystals as building blocks, which show high responsivity as well as fast response in both the visible (one-photon absorption process) and the near infrared (NIR) region (two-photon absorption process). We also elucidated the underlying mechanism for the enhanced photoresponse by efficient charge collection, low trap density and high charge carrier mobility in the MCs.In order to develop environmentally friendly materials, we replaced the lead element with less toxic bismuth in LHP structures to form the bismuth-based perovskite NCs, which exhibit tunable PL but with low quantum yield. The photophysical studies in such NCs with time-resolved spectroscopy attributed the low PL emission intensity to a fast trapping process.

AB - The demand and consumption of energy is increasing dramatically all around the world. Broad adoption of fossil fuels has triggered an enormous threat to the environment. To ensure sustainability of our species and habitat, new solutions to fulfill the energy demand have to be found. Innovative materials offer the possibility to generate scalable renewable energy, which is efficient and environmentally friendly. In recent years, it was demonstrated that lead halide perovskite (LHP) materials prepared with superior optoelectronic properties which are desirable for solar-cell applications. Moreover, the solution processing ensures cheap production of those materials. In order to optimize and widely adopt LHPs as a key component for solar energy generators, it is important to understand the fundamental photophysical processes governing their unique behavior. In this thesis we studied the photophysics of LHP nano- (NC) and microcrystals (MC) using spectroscopic methods. We investigated the photostability of NCs, and found the light irradiation induced particle aggregation. Furthermore, we revealed large two-photon absorption cross sections of these NCs, and we conclude that the two-photon absorption process populates the exciton band through a virtual state. Moreover, we have demonstrated the crucial role of size distribution in explaining the difference between the one-photon excited and two-photon excited photoluminescence (PL).We fabricated photodetectors using micrometer-sized LHP crystals as building blocks, which show high responsivity as well as fast response in both the visible (one-photon absorption process) and the near infrared (NIR) region (two-photon absorption process). We also elucidated the underlying mechanism for the enhanced photoresponse by efficient charge collection, low trap density and high charge carrier mobility in the MCs.In order to develop environmentally friendly materials, we replaced the lead element with less toxic bismuth in LHP structures to form the bismuth-based perovskite NCs, which exhibit tunable PL but with low quantum yield. The photophysical studies in such NCs with time-resolved spectroscopy attributed the low PL emission intensity to a fast trapping process.

KW - Ultrafast spectroscopy

KW - Two-photon absorption

KW - Perovskite

KW - Nanocrystals

KW - Photostability

KW - Lead free perovskite

M3 - Doctoral Thesis (compilation)

SN - 978-91-7422-567-9

PB - Lund University, Faculty of Science, Department of Chemistry, Division of Chemical Physics

CY - Lund

ER -

Photophysics of Perovskite Nano- and Microcrystals

Sammanfattning

Bibliografisk information

Ämnesklassifikation (UKÄ)

FN:s Globala mål

Tillgång till dokument

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Forskningsoutput

Enhanced Size Selection in Two-Photon Excitation for CsPbBr3 Perovskite Nanocrystals

Ultrasensitive and Fast All-Inorganic Perovskite-Based Photodetector via Fast Carrier Diffusion

Size-And Wavelength-Dependent Two-Photon Absorption Cross-Section of CsPbBr3 Perovskite Quantum Dots

Citera det här

Enhanced Size Selection in Two-Photon Excitation for CsPbBr₃ Perovskite Nanocrystals

Size-And Wavelength-Dependent Two-Photon Absorption Cross-Section of CsPbBr₃ Perovskite Quantum Dots