David Caffrey

David Caffrey


Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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24 November 2015 in Journal of Materials Chemistry C
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Journal Article
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LFLeo Farrell
Leo Farrell
ENEmma Norton
Emma Norton
CSChristopher M. Smith
Christopher M. Smith
DCDavid Caffrey
David Caffrey
ISIgor V. Shvets
Igor V. Shvets
KFKarsten Fleischer
Karsten Fleischer
The delafossite structured CuCrO2 system is well known as p-type transparent conducting oxide. We have synthesized a Cu deficient form at low process temperature maintaining its good conductive properties.

2 March 2015 in Physical Review B
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Journal Article
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LFL. Farrell
L. Farrell
KFKarsten Fleischer
Karsten Fleischer
DCDavid Caffrey
David Caffrey
DMD. Mullarkey
D. Mullarkey
ENE. Norton
E. Norton
ISI. V. Shvets
I. V. Shvets
Epitaxial p-type transparent conducting oxide (TCO) Cr2O3:Mg was grown by electron-beam evaporation in a molecular beam epitaxy system on c-plane sapphire. The influence of Mg dopants and the oxygen partial pressure were investigated by thermoelectric and electrical measurements. The conduction mechanism is analyzed using the small-polaron hopping model, and hopping activation energies have been determined, which vary with doping concentration in the range of 210–300 ± 5 meV. Films with better conductivity were obtained by postannealing. The effect of postannealing is discussed in terms of a crystallographic reordering of the Mg dopant. The highest Seebeck mobilities obtained from thermoelectric measurements are of the order of 10−4cm2V−1s−1. We investigate the fundamental properties of a Mg dopant in a high crystalline quality epitaxial film of a binary oxide, helping us understand the role of short range crystallographic order in a p-type TCO in detail.

1 September 2017 in Materials
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Journal Article
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KFKarsten Fleischer
Karsten Fleischer
ENEmma Norton
Emma Norton
DMDaragh Mullarkey
Daragh Mullarkey
DCDavid Caffrey
David Caffrey
ISIgor V. Shvets
Igor V. Shvets
Screening for potential new materials with experimental and theoretical methods has led to the discovery of many promising candidate materials for p-type transparent conducting oxides. It is difficult to reliably assess a good p-type transparent conducting oxide (TCO) from limited information available at an early experimental stage. In this paper we discuss the influence of sample thickness on simple transmission measurements and how the sample thickness can skew the commonly used figure of merit of TCOs and their estimated band gap. We discuss this using copper-deficient CuCrO 2 as an example, as it was already shown to be a good p-type TCO grown at low temperatures. We outline a modified figure of merit reducing thickness-dependent errors, as well as how modern ab initio screening methods can be used to augment experimental methods to assess new materials for potential applications as p-type TCOs, p-channel transparent thin film transistors, and selective contacts in solar cells.

15 February 2023 in ACS Applied Nano Materials
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Journal Article
Open access
AAArdak Ainabayev
Ardak Ainabayev
DMDaragh Mullarkey
Daragh Mullarkey
BWBrian Walls
Brian Walls
DCDavid Caffrey
David Caffrey
Kuanysh ZhussupbekovKuanysh Zhussupbekov
Kuanysh Zhussupbekov
ISIgor Shvets
Igor Shvets

21 September 2020 in ACS Applied Electronic Materials
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Journal Article
Closed access
YNYashaswi Nalawade
Yashaswi Nalawade
JPJoshua Pepper
Joshua Pepper
AHAndrew Harvey
Andrew Harvey
AGAideen Griffin
Aideen Griffin
DCDavid Caffrey
David Caffrey
JCJonathan N. Coleman
Jonathan N. Coleman

6 March 2024 in Advanced Science
Verified
Journal Article
Open access
DCDavid Caffrey
David Caffrey
TGTumpa Gorai
Tumpa Gorai
BRBláithín Rawson
Bláithín Rawson
Miguel Martínez-CalvoMiguel Martínez-Calvo
Miguel Martínez-Calvo
Jonathan KitchenJonathan Kitchen
Jonathan Kitchen
TGThorfinnur Gunnlaugsson
Thorfinnur Gunnlaugsson
The synthesis of a family of chiral and enantiomerically pure pyridyl‐diamide (pda) ligands that upon complexation with europium [Eu(CF3SO3)3] result in chiral complexes with metal centered luminescence is reported; the sets of enantiomers giving rise to both circular dichroism (CD) and circularly polarized luminescence (CPL) signatures. The solid‐state structures of these chiral metallosupramolecular systems are determined using X‐ray diffraction showing that the ligand chirality is transferred from solution to the solid state. This optically favorable helical packing arrangement is confirmed by recording the CPL spectra from the crystalline assembly by using steady state and enantioselective differential chiral contrast (EDCC) CPL Laser Scanning Confocal Microscopy (CPL‐LSCM) where the two enantiomers can be clearly distinguished.