Photophysics of Perovskite Nano- and Microcrystals

Research output: ThesisDoctoral Thesis (compilation)

Standard

Photophysics of Perovskite Nano- and Microcrystals. / Chen, Junsheng.

Lund : Lund University, Faculty of Science, Department of Chemistry, Division of Chemical Physics, 2018. 146 p.

Research output: ThesisDoctoral Thesis (compilation)

Harvard

Chen, J 2018, 'Photophysics of Perovskite Nano- and Microcrystals', Doctor, Lund University, Lund.

APA

Chen, J. (2018). Photophysics of Perovskite Nano- and Microcrystals. Lund University, Faculty of Science, Department of Chemistry, Division of Chemical Physics.

CBE

Chen J. 2018. Photophysics of Perovskite Nano- and Microcrystals. Lund: Lund University, Faculty of Science, Department of Chemistry, Division of Chemical Physics. 146 p.

MLA

Chen, Junsheng Photophysics of Perovskite Nano- and Microcrystals Lund: Lund University, Faculty of Science, Department of Chemistry, Division of Chemical Physics. 2018.

Vancouver

Chen J. Photophysics of Perovskite Nano- and Microcrystals. Lund: Lund University, Faculty of Science, Department of Chemistry, Division of Chemical Physics, 2018. 146 p.

Author

Chen, Junsheng. / Photophysics of Perovskite Nano- and Microcrystals. Lund : Lund University, Faculty of Science, Department of Chemistry, Division of Chemical Physics, 2018. 146 p.

RIS

TY - THES

T1 - Photophysics of Perovskite Nano- and Microcrystals

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 -