The idea is to control the optical properties of functional gain materials such as perovskites by hierarchical structuring of dielectric and semiconducting materials.
We will introduce grating structures with hierarchical length scales to spatially shape field distributions and to control the emissivity, absorptivity, and lifetime of optical devices.
The light-structure interaction will be investigated by near-field optical microscopy and time-resolved spectroscopy.
Investigation of Nano- to Micro-scale Patterning Effects on Perovskite Thin Films and Devices
Supervisor: J. Jasieniak, Chemistry, MON
Co-supervisor: M. Retsch, Chemistry, UBT, A. Funston, Chemistry, MON
Metal halide perovskites have emerged as a promising photovoltaic materials due to their high efficiency, spectral tunability and low cost processability.
These properties make such materials particularly interesting also for solar window applications, although achieving high efficiency with controlled color and optimised transparency and reflectivity remain as major challenges.
This project will investigate the nature of light absorption, transmission and reflection in stand-alone perovskite films and solar cells with nano- and micro-patterned features.
By controlling the patterned perovskite length-scale and its degree of ordering through advanced printing and patterning methologies, it is anticipated that color-tunable and high-efficiency perovskite thin films and solar technologies will be conceived.
The ideal candidate is somebody who likes to work in a team, is curious, and has an undergraduate background in materials, chemistry, physics, process engineering, or a related field.
Unravelling Interactions between Nano- and Micro- Scale Patterned Structures and Perovskite Gain Materials in the Near-field at High Spatial Resolution
Supervisor: A. Funston, Chemistry, MON
Co-supervisor: J. Jasieniak, Chemistry, MON; M. Retsch, Chemistry, UBT
This project will answer the questions: "How do 2D patterns control the emission and propagation of emission in the near-field and far-field?", and "What is the influence of the patterned array compared to the morphology and/or patterning of the perovskite?"
Thin films with both dielectric patterning and structure in the perovskite layer will be fabricated and their optical properties understood.
Optical characterisation will include both time- and spatially- resolved spectroscopy (scanning near-field optical microscopy (SNOM), time-resolved confocal microscopy, and single particle spectroscopy) to understand the near-field emission of perovskite/structured dielectric both separately and combined, the lifetime of near-field emission and propagation of energy.
Investigating Order to Disorder in Nano- to Micro- Scale Patterned Dielectric Arrays
Supervisor: M. Retsch, Chemistry, UBT
Co-supervisor: J. Jasieniak, Chemistry, MON; A. Funston, Chemistry, MON
The project will focus on dedicated two-dimensional structures comprising length scales from a few hundred nanometres accessible through nanosphere lithography up to several tens of micrometres accessible through direct write lithography.
A core question is the role of disorder on the optical excitation, being far less understood compared to highly periodic structures.
We aim to control and quantify the degree of order/disorder through colloidal self-assembly techniques.
A key material focus for this work will be to understand the impacts of the degree of periodicity in such dielectric structures on metal halide perovskites as a light-absorbing material.
Perovskites possess an ABX3 structure, where A is a monovalent cation (i.e. methylammonium), B is a divalent cation (typically lead) and X are halides (Cl, Br and I).
By tuning the halide composition, the optical band-edge can be shifted across the entire visible spectrum, thus permitting the study of cavity modes with the optical resonances within the perovskites.
These hierarchical structures will be investigated with UV/Vis/NIR and MIR spectroscopy.
In cooperation with our partners, we will evaluate how such mesostructures may be included in future photovoltaic devices and how it governs the local field distributions.
