IV-VI Semiconductor Nanosheets for Advanced Optoelectronic Applications

Lead Research Organisation: University of Manchester
Department Name: Materials

Abstract

Two-dimensional materials have revolutionised materials science, and the academic impact of graphene is unique. However to produce advanced optoelectronic devices, a future 2D materials industry will also require 2D semiconductors compatible with conducting graphene. Recently at Manchester we have become interested in unlocking solution processing pathways towards useful 2D semiconductors beyond graphene for direct print inks. This project will explore some of these materials and their device applications and we are seeking an ambitious Ph.D. student to undertake cutting edge research in this area.

We have significant expertise in the area of exfoliation of layered crystals into 2D materials (e.g. Lewis and co-workers Chem. Commun., 2016, 52, 7878-7881 and Chem. Commun. 50, 13338-13341) and we have recently demonstrated that tin(II) sulfide (SnS) nanosheets can be produced in solution by the liquid phase exfoliation of layered herzenbergite (Lewis & Derby co-workers, J.Am. Chem. Soc. 2015, 137, 12689) . We now seek to tune the energy of the band gap continually across this entire 1 - 2 eV energy range. The successful candidate will develop careful ultrasonication, centrifugation and fractionation protocols for the isolation of SnS nanosheets of various thicknesses, thus enabling access to 'made to order' nanosheets of a certain thickness and thus band gap energy.

As a range of IV-VI semiconductors (SnSe, GeS, GeSe), are also layer structures, this approach will be applied in general to produce the family of quantum confined nanosheets with tuneable bandgaps, using top-down solution processing. This will produce a range of useful semiconductor nanosheets with band gaps across the spectral range that can be produced in copious amounts for use as direct-printable inks. Your practical work will be supported by theoretical calculations from our collaborators in Germany

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509565/1 01/10/2016 30/09/2021
1906056 Studentship EP/N509565/1 18/09/2017 30/09/2021 Kane Norton
 
Description Cascade centrifugation has been performed on 2 different materials (SnS and GeS), allowing the nanosheets to be separated by size, the properties of these nanosheets have been characterised.
SnS can be prepared into a film via the Langmuir-Blodgett method. A fraction of nanosheets has been used in the creation of a thin film at the water air interface in a Langmuir-Blodgett trough, the film has been characterised, the method was found to coat onto a variety of materials. A paper is underway on this work, electrical measurements may still be needed.
Each of the different fractions of the cascade centrifuged SnS has been assembled at the liquid liquid interface between hexane and water, these films have all been characterised
Zinc oxide has been grown via CVD as a window layer for the creation of light sensitive devices, the ZnO coated onto transparent conductive oxide substrates have had multiple layers of SnS coated onto them via the liquid liquid interface assembly method. Electrodes have been added and the devices have been tested, showing a response to light under bias although do not function as a solar cell without bias.
An additional layer of CdS as a buffer layer between the SnS and ZnO does not appear to improve the devices and appears to reduce the current obtained under illumination.
Printable inks of size separated SnS sheets have been created via replacement of the exfoliation solvent with a mix of 2-propanol and 2-butanol
Significant contribution to a paper "Synthetic 2-D lead tin sulfide nanosheets with tuneable optoelectronic properties from a potentially scalable reaction pathway" first name author. Primarily synthesis of powder and AFM
Contributing author to "Bimodal PET/MR Imaging Using Biocompatible 89Zr-doped Akaganeite Nanorods"
Exploitation Route Improving upon current work by improving lateral nanosheet size, improving efficiency of current devices, creation of flexible devices, flexible photodetectors with a range of band gaps, improvements to SnS inks including optimising concentrations and potential development of water based stable SnS inks.
Sectors Digital/Communication/Information Technologies (including Software),Electronics,Energy,Environment

URL https://pubs.rsc.org/en/content/articlepdf/2019/sc/c8sc04018d
 
Description collaboration for paper: Synthetic 2-D lead tin sulfide nanosheets with tuneable optoelectronic properties from a potentially scalable reaction pathway 
Organisation Technical University of Dresden
Country Germany 
Sector Academic/University 
PI Contribution synthesis, exfoliation and analysis of nanosheets
Collaborator Contribution calculation of band gaps, dft, band structure
Impact Creation of paper: Synthetic 2-D lead tin sulfide nanosheets with tuneable optoelectronic properties from a potentially scalable reaction pathway Calculations match data obtained from testing of material
Start Year 2018