Printable 2d Material Optoelectronics and Photonics
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Authors
Advisors
Hasan, Tawfique
Date
2017-12-05Awarding Institution
University of Cambridge
Author Affiliation
Engineering
Qualification
Doctor of Philosophy (PhD)
Language
English
Type
Thesis
Metadata
Show full item recordCitation
Hu, G. (2017). Printable 2d Material Optoelectronics and Photonics (Doctoral thesis). https://doi.org/10.17863/CAM.17171
Abstract
Graphene and structurally similar 2-dimensional (2d) materials such as transition metal dichalcogenides (TMDs) and black phosphorus (BP) hold enormous potential for the next generation optoelectronics and photonics. Pairing 2d materials with printing is an emerging cost-effective large-scale device fabrication strategy. However, the current inks are far from ideal to support reproducible device fabrication. In addition, the instability of BP in ambient limits its applications.
In this thesis, I present formulation of 2d material inks for inkjet printing for optoelectronic and photonic applications. To begin with, I produce mono- and few-layer 2d material flakes via ultrasonic assisted liquid phase exfoliation. This allows one-step formulation of a polymer stabilised graphene ink. For TMDs and BP, I design a binary solvent carrier for binder-free ink formulation. I show that these 2d material inks have optimal fluidic properties, drying dynamics and interaction with substrates for spatially uniform, highly controllable and print-to-print consistent large-scale printing on untreated substrates. In particular, the rapid ink drying at low temperatures leads to minimal oxidation of BP during ambient printing; the printed BP with passivation retains a stability over one month. On this basis, the printed graphene is employed as active sensing layer in CMOS integrated humidity sensors and as counter-electrodes in dye-sensitised solar cells, while the printed TMDs and BP are used to develop nonlinear photonic devices (i.e. saturable absorbers for femtosecond pulsed laser generation) and visible to near-infrared photodetectors (e.g. MoS$_2$ and BP/graphene/silicon hybrid photodetectors).
Beyond inkjet printing, I present an ink formulation of commercial graphene nanoplatelets for roll-to-roll flexographic press ($\sim$100 m min$^{−1}$ printing speed). This allows hundreds of conductive electronic circuits to be printed in a minute for capacitive touchpads.
Though I investigate only graphene, TMDs and BP, the ink formulation strategies can be effortlessly transferred to other 2d materials such as boron nitride, MXenes and mica. In addition to the demonstrated applications, printing of 2d materials can be potentially exploited to fabricate devices such as transistors, light emitters, energy storage conversion, and biosensors. This significantly expands the prospect of printable 2d material optoelectronics and photonics.
Keywords
Graphene, 2-dimensional materials, Printing, Optoelectronics, Photonics
Sponsorship
China Scholarship Council, Cambridge Overseas Trust, and St John’s College.
Identifiers
This record's DOI: https://doi.org/10.17863/CAM.17171
Rights
No Creative Commons licence (All rights reserved), All Rights Reserved
Licence URL: https://www.rioxx.net/licenses/all-rights-reserved/
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