Professor Robert Taylor: Publications

Stability of mixed lead halide perovskite films encapsulated in cyclic olefin copolymer at room and cryogenic temperatures

The Journal of Physical Chemistry Letters American Chemical Society 14:50 (2023) 11333-11341

Authors:

Mutibah Alanazi, Ashley Marshall, Shaoni Kar, Yincheng Liu, Jinwoo Kim, Henry Snaith, Robert Taylor, Tristan Farrow

Abstract:

Lead Mixed Halide Perovskites (LMHPs), CsPbBrI₂, have attracted significant interest as promising candidates for wide bandgap absorber layers in tandem solar cells due to their relative stability and red-light emission with a bandgap ∼1.7 eV. However, these materials segregate into Br-rich and I-rich domains upon continuous illumination, affecting their optical properties and compromising the operational stability of devices. Herein, we track the microscopic processes occurring during halide segregation by using combined spectroscopic measurements at room and cryogenic temperatures. We also evaluate a passivation strategy to mitigate the halide migration of Br/I ions in the films by overcoating with cyclic olefin copolymer (COC). Our results explain the correlation between grain size, intensity dependencies, phase segregation, activation energy barrier, and their influence on photoinduced carrier lifetimes. Importantly, COC treatment increases the lifetime charge carriers in mixed halide thin films, improving efficient charge transport in perovskite solar cell applications.

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Ultranarrow line width room-temperature single-photon source from perovskite quantum dot embedded in optical microcavity

Nano Letters American Chemical Society 23:23 (2023) 10667-10673

Authors:

tristan Farrow, Robert Taylor

Abstract:

Ultranarrow bandwidth single-photon sources operating at room-temperature are of vital importance for viable optical quantum technologies at scale, including quantum key distribution, cloud-based quantum information processing networks, and quantum metrology. Here we show a room-temperature ultranarrow bandwidth single-photon source generating single-mode photons at a rate of 5 MHz based on an inorganic CsPbI₃ perovskite quantum dot embedded in a tunable open-access optical microcavity. When coupled to an optical cavity mode, the quantum dot room-temperature emission becomes single-mode, and the spectrum narrows down to just ∼1 nm. The low numerical aperture of the optical cavities enables efficient collection of high-purity single-mode single-photon emission at room-temperature, offering promising performance for photonic and quantum technology applications. We measure 94% pure single-photon emission in a single-mode under pulsed and continuous-wave (CW) excitation.

Gain enhancement of perovskite nanosheets by a patterned waveguide: excitation and temperature dependence of gain saturation

Light: Science & Applications Springer Nature 12:1 (2023) 285

Authors:

Inhong Kim, Ga Eul Choi, Ming Mei, Min Woo Kim, Minju Kim, Young Woo Kwon, Tae-In Jeong, Seungchul Kim, Suck Won Hong, Kwangseuk Kyhm, Robert A Taylor

Abstract:

Optical gain enhancement of two-dimensional CsPbBr₃ nanosheets was studied when the amplified spontaneous emission is guided by a patterned structure of polyurethane-acrylate. Given the uncertainties and pitfalls in retrieving a gain coefficient from the variable stripe length method, a gain contour g(ℏω, x) was obtained in the plane of spectrum energy (ℏω) and stripe length (x), whereby an average gain was obtained, and gain saturation was analysed. Excitation and temperature dependence of the gain contour show that the waveguide enhances both gain and thermal stability due to the increased optical confinement and heat dissipation, and the gain origins were attributed to the two-dimensional excitons and the localized states.

Ultranarrow linewidth room-temperature single-photon source from perovskite quantum dot embedded in optical microcavity

(2023)

Authors:

Amit R Dhawan, Tristan Farrow, Ashley Marshall, Alex Ghorbal, Wonmin Son, Henry J Snaith, Jason M Smith, Robert A Taylor

Three-photon excitation of quantum two-level systems

CLEO 2023 Optica Publishing Group (2023)

Authors:

V Villafane, B Scaparra, M Rieger, S Appel, R Trivedi, Ra Oliver, Robert A Taylor, Jj Finley, K Müller

Abstract:

We demonstrate that a two-level system, in form of an InGaN quantum dot, can only be efficiency excited using an odd number of photons (1 or 3) while resonant two-photon excitation is strongly suppressed.

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