Precursor Chemistry and the CVD of Transparent Conducting Oxides

Lead Research Organisation: University College London
Department Name: Chemistry

Abstract

This project will involve the investigation of alternative precursors and deposition technologies in order to improve performance and enable next generation transparent conducting oxide (TCO) films to be developed.

Indium tin oxide (ITO) is the current TCO of choice for most industrial applications but it has many limitations, such as modest conductivity (2000-4000 S/cm), a relatively low work function and some optical absorption in the blue-green spectral region. In addition, indium is expensive since it is in relatively short supply, which presents a significant challenge for larger-scale production of next generation photovolatic technologies and flat panel displays. It is therefore crucial to develop alternative TCO materials with no indium with improved optical and electrical properties. Alternatives to ITO include doped ZnO (ZnO:Al, ZnO:Ga, ZnO:SnO2) and doped SnO2 (SnO2:Sb, SnO2:F, ZnO-SnO2) and many of these have been investigated in their bulk form. However, studies of some of these materials as thin films is limited and for many of the applications thin films are required. An ideal method for preparing thin fims for large scale applications is chemical vapour deposition (CVD) given that films with good uniformity and compositional control, large area growth and step coverage can be achieved. However, for a successful CVD process, a volatile precursor is necessary which is prefereably a liquid or low metling solid for atmospheric pressure CVD or highly soluble for liquid based (aerosol assisted) CVD. Current precursors to TCO materials, particularly indium and zinc still suffer from chemical instability, poor reproducibility in the growth process and less than favourable vapour pressures and reactivity for film growth.

This work aims to develop highly volatile and soluble precursors based on metal ketoiminates. The advantages of using the ketoiminate ligand include:
- reactive complexes can be formed in high yield
- complexes with a hign vapour pressure can be formed as monomeric species are isolated
- thermal stability of the metal complexes can be increased by tuning the groups attached to the nitrogen atoms
- the surface reaction between the metal precursor and the surface of the substrate can be enhanced due to the high chemical reactivity of the complexes.

TCO materials to be investigated include doped-ZnO and doped-SnO2. We have the ability to lay down thin films using a new combinatorial aerosol-assisted (AA)CVD reactor for solution based and also a combinatorial APCVD reactor to make films of graded composition. This new reactor enables upto 400 different compositions to be made on a single plate in one CVD experiment. This is important as it will enable us to rapidly screen composition space make idealised and optimised compositions for TCO applications. This combined approach will enable us to investigate different combinations and go towards achieving the next generation TCO materials.

Planned Impact

This project will have impact through the development of alternative precursors and deposition of thin films of new transparent conducting oxides (TCOs). Solar energy panels offer alternative solutions for a range of energy requirements, for example, Pilkington TCO glass is used in the manufacture of thin plate panels used in the direct conversion of solar radiation to electricity. The thin film solar market is predicted to grow six-fold over the next 5 years to 2GW by 2015. As such, there is significant pressure to supply large volumes of high quality transparent conducting oxides with a range of properties suitable to meet the differing requirements that thin film solar cell manufacturers demand. Solar energy panels offer alternative solutions for a range of energy requirements, from small-scale domestic applications to large-scale solar power stations, from cloudy northern rooftops to hot sunny deserts. TCO films are a key component of these applications and the development of improved TCO films will benefit the public, for example by supplying electricity with a very low environmental footprint. The reduction of fuel costs and the development of improved TCOs will have significant impact on the public sector. With increasing legislation in place via international agreements to reduce greenhouse gases to acceptable levels the development of alternative energy, such as solar-power is clearly of great importance and will reduce the need for fossil fuels.

Publications

10 25 50
 
Description In this project precursor development was investigated for their use in depositing high quality transparent conducting oxide films. These materials are used in window coatings, solar powered panels, phones and computers and micro electrode arrays.Good progress was made in developing novel precursors for use in aerosol assisted CVD. Some of the precursors are currently being studied by an industrial partner to evaluate them and a patent had been published.
Exploitation Route It will be linked into the large manufacturing grant we received funding for which aims at developing scaled up routes for film deposition.
Sectors Manufacturing, including Industrial Biotechology

URL http://google.com/patents/WO2016132100A1?cl=en
 
Description A patent has been granted on the use of a particular type of precursor for the deposition of metal or metal oxide thin films. Eight publications have also results so far from this project.
First Year Of Impact 2017
Sector Chemicals,Manufacturing, including Industrial Biotechology
Impact Types Economic

 
Description Materially Better Physical Sciences: A Prospectus for the UK Materials Science Community
Geographic Reach National 
Policy Influence Type Participation in advisory committee
URL http://www.epsrc.ac.uk/newsevents/pubs/materiallybetterphysicalsciences/
 
Description Co-doped TCO Films
Amount £80,000 (GBP)
Organisation University College London 
Department Department of Chemistry
Sector Academic/University
Country United Kingdom
Start 09/2013 
End 09/2016
 
Description Porous Complexes for Structural Determination
Amount £108,000 (GBP)
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 09/2014 
End 09/2018
 
Description Sustainable Manufacturing of Transparent Conducting Oxide (TCO) Inks and Thin Films
Amount £2,281,220 (GBP)
Funding ID EP/L017709/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 03/2014 
End 02/2019
 
Description Zinc Oxide Precursors and Film Deposition
Amount £80,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 09/2012 
End 09/2015
 
Description NSG 
Organisation Pilkington Glass
Department Pilkington Technology Centre
Country United Kingdom 
Sector Private 
PI Contribution Identifying precursors for use in thin film deposition of functional materials
Collaborator Contribution Testing precursors in scale rigs and completing patent on potentially commercial precursors
Impact Patent and publications as well as further investment in grants
 
Description Sustainable Manufacturing of Transparent Conducting Oxides 
Organisation AkzoNobel
Department Research, Development and Innovation
Country Netherlands 
Sector Private 
PI Contribution The project represents a significant collaboration between academia and industrial sector organisations. The collaborators will provide an application context for the developments. We are working closely with industrial partners, particularly NSG (Pilkington) who are the world's largest supplier of TCO glass and have considerable interests in photovoltaic stacks. NSG have collaborated with UCL for ~20 years and have funded CASE awards etc and are well placed to commercialise developments from the project under the appropriate licensing agreements. They have the expertise and equipment to investigate scale-up. We are also working closely with our other industry partners who are interested in the development of nanoceramics for TCOs in photovoltaics as printed inks (e.g. Teer Coatings), in order to ensure that outcomes are regularly disseminated and discussed.
Collaborator Contribution All have attended regular quarterly project meetings and provided expert advice. Sun Chemical have provided expert guidance and resources to enable us to develop inks and Malvern are helping with rheology. Beer coatings have taken our sample and sputtered films. NSG provide regular input and help with the design of the scale up system as well as providing samples.
Impact None yet but the project is only part way through.
Start Year 2014
 
Description Sustainable Manufacturing of Transparent Conducting Oxides 
Organisation Malvern Instruments
Country United Kingdom 
Sector Private 
PI Contribution The project represents a significant collaboration between academia and industrial sector organisations. The collaborators will provide an application context for the developments. We are working closely with industrial partners, particularly NSG (Pilkington) who are the world's largest supplier of TCO glass and have considerable interests in photovoltaic stacks. NSG have collaborated with UCL for ~20 years and have funded CASE awards etc and are well placed to commercialise developments from the project under the appropriate licensing agreements. They have the expertise and equipment to investigate scale-up. We are also working closely with our other industry partners who are interested in the development of nanoceramics for TCOs in photovoltaics as printed inks (e.g. Teer Coatings), in order to ensure that outcomes are regularly disseminated and discussed.
Collaborator Contribution All have attended regular quarterly project meetings and provided expert advice. Sun Chemical have provided expert guidance and resources to enable us to develop inks and Malvern are helping with rheology. Beer coatings have taken our sample and sputtered films. NSG provide regular input and help with the design of the scale up system as well as providing samples.
Impact None yet but the project is only part way through.
Start Year 2014
 
Description Sustainable Manufacturing of Transparent Conducting Oxides 
Organisation Manufacturing Technology Centre (MTC)
Country United Kingdom 
Sector Private 
PI Contribution The project represents a significant collaboration between academia and industrial sector organisations. The collaborators will provide an application context for the developments. We are working closely with industrial partners, particularly NSG (Pilkington) who are the world's largest supplier of TCO glass and have considerable interests in photovoltaic stacks. NSG have collaborated with UCL for ~20 years and have funded CASE awards etc and are well placed to commercialise developments from the project under the appropriate licensing agreements. They have the expertise and equipment to investigate scale-up. We are also working closely with our other industry partners who are interested in the development of nanoceramics for TCOs in photovoltaics as printed inks (e.g. Teer Coatings), in order to ensure that outcomes are regularly disseminated and discussed.
Collaborator Contribution All have attended regular quarterly project meetings and provided expert advice. Sun Chemical have provided expert guidance and resources to enable us to develop inks and Malvern are helping with rheology. Beer coatings have taken our sample and sputtered films. NSG provide regular input and help with the design of the scale up system as well as providing samples.
Impact None yet but the project is only part way through.
Start Year 2014
 
Description Sustainable Manufacturing of Transparent Conducting Oxides 
Organisation Pilkington Glass
Department Pilkington Technology Centre
Country United Kingdom 
Sector Private 
PI Contribution The project represents a significant collaboration between academia and industrial sector organisations. The collaborators will provide an application context for the developments. We are working closely with industrial partners, particularly NSG (Pilkington) who are the world's largest supplier of TCO glass and have considerable interests in photovoltaic stacks. NSG have collaborated with UCL for ~20 years and have funded CASE awards etc and are well placed to commercialise developments from the project under the appropriate licensing agreements. They have the expertise and equipment to investigate scale-up. We are also working closely with our other industry partners who are interested in the development of nanoceramics for TCOs in photovoltaics as printed inks (e.g. Teer Coatings), in order to ensure that outcomes are regularly disseminated and discussed.
Collaborator Contribution All have attended regular quarterly project meetings and provided expert advice. Sun Chemical have provided expert guidance and resources to enable us to develop inks and Malvern are helping with rheology. Beer coatings have taken our sample and sputtered films. NSG provide regular input and help with the design of the scale up system as well as providing samples.
Impact None yet but the project is only part way through.
Start Year 2014
 
Description Sustainable Manufacturing of Transparent Conducting Oxides 
Organisation Plasma Quest
Country United Kingdom 
Sector Private 
PI Contribution The project represents a significant collaboration between academia and industrial sector organisations. The collaborators will provide an application context for the developments. We are working closely with industrial partners, particularly NSG (Pilkington) who are the world's largest supplier of TCO glass and have considerable interests in photovoltaic stacks. NSG have collaborated with UCL for ~20 years and have funded CASE awards etc and are well placed to commercialise developments from the project under the appropriate licensing agreements. They have the expertise and equipment to investigate scale-up. We are also working closely with our other industry partners who are interested in the development of nanoceramics for TCOs in photovoltaics as printed inks (e.g. Teer Coatings), in order to ensure that outcomes are regularly disseminated and discussed.
Collaborator Contribution All have attended regular quarterly project meetings and provided expert advice. Sun Chemical have provided expert guidance and resources to enable us to develop inks and Malvern are helping with rheology. Beer coatings have taken our sample and sputtered films. NSG provide regular input and help with the design of the scale up system as well as providing samples.
Impact None yet but the project is only part way through.
Start Year 2014
 
Description Sustainable Manufacturing of Transparent Conducting Oxides 
Organisation Sun Chemical Ltd
Country Canada 
Sector Private 
PI Contribution The project represents a significant collaboration between academia and industrial sector organisations. The collaborators will provide an application context for the developments. We are working closely with industrial partners, particularly NSG (Pilkington) who are the world's largest supplier of TCO glass and have considerable interests in photovoltaic stacks. NSG have collaborated with UCL for ~20 years and have funded CASE awards etc and are well placed to commercialise developments from the project under the appropriate licensing agreements. They have the expertise and equipment to investigate scale-up. We are also working closely with our other industry partners who are interested in the development of nanoceramics for TCOs in photovoltaics as printed inks (e.g. Teer Coatings), in order to ensure that outcomes are regularly disseminated and discussed.
Collaborator Contribution All have attended regular quarterly project meetings and provided expert advice. Sun Chemical have provided expert guidance and resources to enable us to develop inks and Malvern are helping with rheology. Beer coatings have taken our sample and sputtered films. NSG provide regular input and help with the design of the scale up system as well as providing samples.
Impact None yet but the project is only part way through.
Start Year 2014
 
Description Sustainable Manufacturing of Transparent Conducting Oxides 
Organisation Teer Coatings Ltd
Country United Kingdom 
Sector Private 
PI Contribution The project represents a significant collaboration between academia and industrial sector organisations. The collaborators will provide an application context for the developments. We are working closely with industrial partners, particularly NSG (Pilkington) who are the world's largest supplier of TCO glass and have considerable interests in photovoltaic stacks. NSG have collaborated with UCL for ~20 years and have funded CASE awards etc and are well placed to commercialise developments from the project under the appropriate licensing agreements. They have the expertise and equipment to investigate scale-up. We are also working closely with our other industry partners who are interested in the development of nanoceramics for TCOs in photovoltaics as printed inks (e.g. Teer Coatings), in order to ensure that outcomes are regularly disseminated and discussed.
Collaborator Contribution All have attended regular quarterly project meetings and provided expert advice. Sun Chemical have provided expert guidance and resources to enable us to develop inks and Malvern are helping with rheology. Beer coatings have taken our sample and sputtered films. NSG provide regular input and help with the design of the scale up system as well as providing samples.
Impact None yet but the project is only part way through.
Start Year 2014
 
Title Deposition process 
Description A process for depositing an inorganic material on a substrate, the process comprising, providing a substrate having a surface, providing a precursor mixture comprising a metal sulfonate, and delivering the precursor mixture to the surface of the substrate, wherein the surface of the substrate is at a substrate temperature of above 450 °C and is sufficient to effect decomposition of the metal sulfonate. The inorganic material may include a metal or a metal oxide. The preferred metal sulfonate is metal triflate. 
IP Reference WO2016132100 
Protection Patent granted
Year Protection Granted 2016
Licensed No
Impact Precursor have been identified which can be used for the deposition of a range of technologically important metal oxides