Microstructure of Organic Semiconductors Controlled by Solution Processing

Lead Research Organisation: Imperial College London
Department Name: Dept of Physics

Abstract

Plastic electronics encompasses the materials science, chemistry and physics of molecular electronic materials and the application of such materials to displays, lighting, flexible thin film electronics, solar energy conversion and sensors. The field is a growth area, nationally and globally, evidenced by the rapidly expanding organic display and printed electronics industries. Such a rapid pace of progress in organic thin-film electronics stems from the ease of processing and patterning of organic compounds, plus prospects for large-area deposition and low-cost. To ensure further progress of organic electronics and thus establishing it as a next generation technology requires an improvement in our ability to control the microstructures of solution-processed films, which, in turn, relies upon our fundamental understanding of the impact of these microstructures on optoelectronic and charge transport properties. The dependence of device performance on the microstructures of organic semiconductors (OSCs) and the factors affecting the development of specific microstructures in thin films are still poorly established and require urgent attention. The proposed research seeks to provide key fundamental and technological insights into this issue. We aim to control the microstructure of OSCs in terms of molecular order, orientation and alignment through solution processing. We targets to elucidate the important parameters during processing that impact the OSC microstructures and thus to identify the relationships between these microstructures and optoelectronic properties of OSCs. Particular attention will be paid to control the microstructure of OSCs (small molecules and conjugated polymers) with different packing structures to understand the role of chemical structures and packing motifs of molecules on the formation of thin film microstructures. Solution processing of advanced device architectures such as blends and multilayers with various length scales controlled will also be attempted to fabricate highly ambitious all printed, flexible, large area organic electronic devices. Three major impacts are expected from this project; (i) to reveal the crucial structure-property relationships of functional molecular materials, (ii) to establish a solution based printing method as a tool to control the microstructures of functional molecular materials, which can be optimised for various optoelectronic devices and (iii) to fabricate more efficient and cheaper devices for solar energy conversion and integrated circuits, which will be a long-term application of the project, will have a clear impact on the achievement of a low-carbon economy, which is currently one of EPSRC's major themes. Therefore, this project is of great relevance to the EPSRC remit.

Planned Impact

Three major impacts are expected from this project.

First, the results of the proposed research will reveal the crucial structure-property relationships of functional molecular materials. The fundamental understanding of the relationships between microstructures and optoelectronic properties of organic semiconductors and to correlate them with the device performance is still an area of open research for molecular electronics, rendering the successful output of this project to be novel. The direct beneficiaries will be a broad section of the electronics research community, both academic and industrial, for whom the information on the basic structures and properties at a molecular level of organic semiconductors obtained in this proposal will be of great interest. Key experimental data on model organic materials for FET and PV applications will aid in the development of understanding and description of molecular-scale, low-dimensional organic electronic systems, and in reconstructing realistic models of relevant thin-film microstructures and device physics based on organic semiconductors. Material synthetic and device engineering strategies, as well as the development of advanced structural imaging technique will directly benefit from this proposed research.

Second, the proposed work will contribute to the flourishing plastic (or printed) electronics industry. The output of the project will establish a solution based printing technique as a tool to control precisely the microstructure of functional molecular materials, which can be optimised for various optoelectronic devices. The manufacture of such a tool will also provide an advantage for the UK instrumentation industry. The impact of the output of this project is global. A solution based printing technique developed and established in this proposal could also be novel in tackling other highly important questions in nanoscale functional materials and devices by allowing us to access certain molecular structures that are not normally achievable and thus to invent new device architectures.

Third, in this project, special attention is devoted to materials and devices of interest to the field of organic electronics. The main tasks of controlling molecular architectures are dedicated to the investigation of organic semiconductor materials and devices, with high ambition to fabricate all printed, flexible, large area organic devices, which are expected to yield a revolution in terms of efficient and cost effective solar cells and transistors. The progress in the development of more efficient and cheaper devices for solar energy conversion and electronic circuits, which will be a long-term application of the project, will have a clear impact on the achievement of a low-carbon economy, which is currently one of EPSRC's major themes. Therefore, this project is of great relevance to the EPSRC remit.

Publications


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Fei Z (2015) Influence of Backbone Fluorination in Regioregular Poly(3-alkyl-4-fluoro)thiophenes. in Journal of the American Chemical Society
Razzell-Hollis J (2017) Effects of Side-Chain Length and Shape on Polytellurophene Molecular Order and Blend Morphology in The Journal of Physical Chemistry C
 
Description In this project, we have developed the methodology to control the microstructures of organic semiconductors through solution-based printing methods and to characterise these structures using analytical tools. Through this methodology, we were able to develop a systematic understanding of important parameters that impact OSC microstructure and morphology during processing, to identify the relationships between microstructures and optoelectronic properties of OSCs, and to correlate them to the performance of their devices.

The output of research performed under this project has already produced more than 20 refereed papers in high impact journals and more than 20 invited talks including a plenary and key lectures in national/ international workshops/ conferences. More importantly, based on the methodology developed in this project, new industrial collaborations via research projects and studentship support have been established with Samsung Electronics (Korea), CSEM (Brasil), KP Technology Ltd (UK), National Physical Laboratory (UK), and CDT Ltd/ Sumitomo Chemical Company (UK/Japan).

The outcome of the project has also been used to build close collaboration relationship with CNRS (France) through the awarded Royal Society International Exchanges Scheme with CNRS to develop New Supramolecular Organic Semiconductors via Advanced Structural Control/Probe, and also with Hong Kong Baptist University and the Changchun Institute for Applied Chemistry to establish trilateral interactions (UK, Hong Kong and China) in Plastic Electronics.

Furthermore, the outcome of the project has been used as the basis of the Global Research Laboratory (GRL) proposal (total, $1.1M) submitted to the Korean Ministry of Science, ICT and Future Planning (MSIP) and National Research Foundation of Korea (NRF). The proposal has been selected for the final interview with the outcome expected by April 2017. The main target of GRL proposal is to develop high-performance flexible and printed organic/inorganic hybrid integrated photovoltaic modules for the next-generation energy sources.
Exploitation Route The insights obtained in this project will be fed back to the industrial collaborators to design new materials and to explore new device fabrication techniques and device architectures to address the specific issues outlined in this proposal. They will be also positioned to advice on end use, market development, environmental impact and manufacturability and assist in job creation in the sector. In addition, the strategic fit with other complementary industrial collaborations such as with instrumentation industry would offer additional exploitation paths. The industrial impact based on our findings is already evident, generating new global industrial collaborations via research project with Samsung (UK) and research CASE studentships with CSEM (Brasil), KP Technology Ltd (UK), National Physical Laboratory (UK), and CDT Ltd/ Sumitomo Chemical Company (UK/Japan).

On the other hand, the main findings resulted from this project will provide new knowledge and scientific advancement in the practical application of organic electronics technologies in academic research. The impact of this work in academic community has been maximised through publication in internationally renowned journals of physics, chemistry and materials science, by plenary and keynoter presentation at international conferences, and by seminars/lectures at universities and companies. Note that the output of research performed under this grant has already produced more than 20 papers in high impact journals.
Sectors Chemicals,Electronics,Energy,Environment,Manufacturing, including Industrial Biotechology
URL https://www.imperial.ac.uk/people/ji-seon.kim
 
Description The main aim of the project was achieved by elucidating the crucial structure-property relationships of functional molecular materials, their microstructures in thin films controlled via solution-processing and characterised by advanced analytical tools. The direct beneficiaries have been a broad section of the electronics research community, both academic and industrial, for whom the information on the basic structures and properties at a molecular level of organic semiconductors obtained in this project was of great interest. In particular, the major scientific findings of this project have contributed to non-academic impact, successfully generating new global industrial collaborations through research projects and CASE studentships listed below. 1. CSEM (Brasil): CASE Project: Printed Large Area Organic Solar Cells (2016-2020) 2. KP Technology Ltd (UK): CASE Project: Morphology control and characterisation of organic and hybrid devices for thin-film electronics (2016-2020) 3. Cambridge Display Technology/Sumitomo Chemical Company (UK/Japan): CASE Project: Towards Full Device Stability for Organic and Hybrid Solar Cells (2015-2019) 4. National Physical Laboratory (NPL, UK): CASE Project: Controlling Microstructure of Organic & Hybrid Materials via Solution Processing (2014-2018) 5. Samsung Electronics (Korea): Research project: High-Performance Organic Near-IR Photodetectors via Advanced Molecular Structure Control and Analysis, Samsung Global Research Outreach (GRO) Programme Grant (2015-2017) In this project, special attention has been devoted to materials and devices of interest to the field of organic electronics. The main tasks of controlling molecular architectures were dedicated to the investigation of organic semiconductor materials and devices, with ambition to fabricate printed, flexible, large area organic devices, which were expected to yield a revolution in terms of efficient and cost effective solar cells and transistors. The project has contributed to the progress in the development of more efficient and cheaper devices for solar energy conversion and electronic circuits, which have a clear impact on the achievement of a low-carbon economy, which is currently one of EPSRC's major themes. Furthermore, the research output has also been used to stimulate scientific discussion in various key international conferences/ workshops, as well as renowned universities and companies in various countries including UK, Korea, China, France, USA, Italy, and Brazil. The research output was also presented in important government meetings between UK and South during the Joint Government Committee Meetings on Science and Technology held by the Korean Ministry of Science, ICT and Future Planning (MSIP) and the UK Foreign Office, Department of Business, Invocation & Skills (BIS, now changed to BEIS) (2015 & 2017). The project has also an impact on people and training. The project was highly interdisciplinary in nature involving both experimental and theoretical aspects of plastic electronic materials and devices. Consequently, the project has provided a perfect environment for the cross-fertilisation of new ideas and perspectives for the appointed researchers. They were exposed not only to technology side of the project, but also to fundamental science to understand the impact of this microstructure that has on OSC optical and charge transport properties and device performance. Each member of the research team, therefore, has developed a range of important and complementary skills as well as an awareness of the broader implications of their research efforts. The project has delivered highly trained and skilled researchers who were also attuned to the economic, social and environmental implications of their scientific and technological advances.
First Year Of Impact 2015
Sector Chemicals,Creative Economy,Electronics,Energy,Environment,Manufacturing, including Industrial Biotechology
Impact Types Societal,Economic
 
Description Korea-UK Joint Government Committee Meeting on Science and Technology
Geographic Reach Asia 
Policy Influence Type Gave evidence to a government review
 
Description 2015 Samsung Global Research Outreach (GRO) Programme Grant
Amount $100,000 (USD)
Organisation Samsung Advanced Institute of Technology 
Sector Private
Country Korea, Republic of
Start 10/2015 
End 09/2016
 
Description EPSRC Centre for Doctoral Training (CDT) in Plastic Electronics Materials
Amount £200,000 (GBP)
Funding ID EP/L016702/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 04/2014 
End 09/2022
 
Description Global Partnerships Fund (GPF)
Amount £43,000 (GBP)
Organisation Government of the UK 
Department Department for Business, Innovation and Skills
Sector Public
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 04/2013 
End 03/2016
 
Description Industrial CASE top-up fund for a PhD studentship
Amount £30,000 (GBP)
Organisation National Physical Laboratory (NPL) 
Sector Academic/University
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 10/2014 
End 09/2018
 
Description Industrial CASE top-up fund for a PhD studentship
Amount £25,000 (GBP)
Organisation CSEM Brasil 
Sector Charity/Non Profit
Country Brazil, Federative Republic of
Start 10/2016 
End 09/2020
 
Description Industrial CASE top-up fund for a PhD studentship
Amount £45,000 (GBP)
Organisation Cambridge Display Technology 
Sector Private
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 10/2015 
End 09/2019
 
Description Industrial CASE top-up fund for a PhD studentship
Amount £23,000 (GBP)
Organisation KP Technology 
Sector Private
Country Unknown
Start 10/2016 
End 09/2020
 
Description RS International Exchanges Scheme with CNRS (France)
Amount £12,000 (GBP)
Organisation The Royal Society 
Sector Academic/University
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 01/2016 
End 12/2017
 
Description Samsung Global Research Outreach (GRO) Program Grant
Amount $100,000 (USD)
Organisation Samsung Advanced Institute of Technology 
Sector Private
Country Korea, Republic of
Start 03/2017 
End 02/2018
 
Title Raman spectroscopy 
Description Raman spectroscopy is an advanced structural nanoprobe for conjugated molecular semiconductors. Utilising selective resonant and polarisation dependent excitations, together with in situ control of temperature, pressure, electrical, and electrochemical potential, we have demonstrated its unique capability to elucidate the properties of molecular semiconductors, including: chemical structure, molecular conformation, order, orientation, and fundamental photo- and electro-chemical processes and stability - all of which are critically important to the performance of a wide range of optical and electronic organic semiconductor devices. 
Type Of Material Improvements to research infrastructure 
Year Produced 2015 
Provided To Others? Yes  
Impact The fast growing field of Nanotechnology strongly needs novel experimental techniques capable of characterising the structure and composition of matter at the nanoscale molecular level. However, not many nanoscale imaging techniques have been developed and established, that have provided the required information with high chemical/ structural sensitivity and high spatial resolution. My team has developed and established an advanced structural nanoimaging technique based on Raman spectroscopy, integrating it with other functionalities such as selective resonant and polarisation dependent excitations, together with in situ control of temperature, pressure, electrical, and electrochemical potential. This method provides a very valuable nanometrology for functional materials and devices. As a result of its unique capabilities, the use of Raman is expected to grow rapidly not only for molecular materials in organic electronics, but also much more broadly into bio- and nano-material related research areas. 
URL https://www.imperial.ac.uk/nanoanalysis-group/research/developing-nanometrology/
 
Title Zone-cast printing technique 
Description Zone-cast technique is a solution-based printing technique which has proven to be a reliable, robust method for controlling the microstructures of organic semiconductors, in particular for small molecules with the added benefit of being compatible with roll-to-roll printing processes currently favoured for large-scale manufacture. Various deposition parameters such as substrate temperature, solution temperature, substrate shift speed, solution injection rate, nozzle-to-substrate distance (meniscus height) and meniscus lateral gradient can be precisely controlled in order to manipulate the molecular order of materials deposited, and thus the structure-property relationships of molecular semiconductors can be identified. 
Type Of Material Improvements to research infrastructure 
Year Produced 2016 
Provided To Others? Yes  
Impact Zone-cast technique provides a reliable, robust method for controlling the microstructures of solution-processible functional materials including molecular semiconductors. 
 
Description Collaboration with CNRS France 
Organisation Pierre and Marie Curie University - Paris 6
Country France, French Republic 
Sector Academic/University 
PI Contribution This is a basic research programme focusing on new organic semiconductors, which leads to advances in the molecular electronics. The direct beneficiaries are individual researchers involved in this collaboration and their institutions (ICL UK and CNRS France) by establishing new collaborations and exchanging their complimentary expertise. This project provides an important framework for potential long-term collaborations between two groups. My team has contributed to this collaboration by developing new methodology to control and characterise organic semiconductors synthesised by the French partner. Key structural data on new organic materials obtained by my team provides important information about molecular-scale, low-dimensional organic electronic systems, reconstructing realistic models of relevant self-organised thin-film structures. Material synthetic and thin film processing, device engineering strategies will directly benefit from this collaboration. This collaboration also brings very valuable benefits to the UK science in the field of flexible thin film electronics.
Collaborator Contribution Desirable electronic properties such as improved charge transport and high carrier mobilities are expected for novel nanostructured supramolecular organic semiconductors (NSOS). NSOS utilises the self-organisation nature of both piconjugated semiconducting polymers and liquid crystals, forming highly ordered supramolecular architectures with the phase separation at the nanoscale tuning these structures. This collaborative research seeks to provide key scientific understanding of NSOS materials, with a particular focus on controlling NSOS structures in thin films via solution-processing and probing these structures using advanced structural probes. The French partner provides new NSOS materials synthesised in his group, which is critical to this collaborative research aiming to elucidate the important structure-property relationships of new NSOS materials.
Impact - Project Review Meetings/ workshop in Paris and London (2016) - A journal paper based on our collaborative work, "Investigation into the relationship between structure and charge transport in liquid-crystalline side-chain pi-conjugated polymers" (submitted)
Start Year 2016
 
Description Industrial collaboration with CSEM Brasil 
Organisation CSEM Brasil
Country Brazil, Federative Republic of 
Sector Charity/Non Profit 
PI Contribution Wrote a research proposal entitled - Printed Large Area Organic Solar Cells Recruited a PhD student Performing / directing the project
Collaborator Contribution Financial support of the project (25000 GBP) Participating in recruitment of a PhD student Contributing to the project including hosting a student in CSEM
Impact Industrial engagement in multi-disciplinary research (Chemistry, Materials, Physics and Engineering)
Start Year 2016
 
Description Industrial collaboration with Cambridge Display Technology 
Organisation Cambridge Display Technology
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Private 
PI Contribution Wrote a research proposal entitled - Towards Full Device Stability for Organic and Hybrid Solar Cells Recruited a PhD student Performing / directing the project
Collaborator Contribution Financial support of the project Contributing to the project via regular project review meetings Hosting a student in the company for a short period
Impact Industrial engagement in multi-disciplinary research (Chemistry, Materials, Physics and Engineering)
Start Year 2015
 
Description Industrial collaboration with KP Technology Ltd 
Organisation KP Technology
Country Unknown 
Sector Private 
PI Contribution Wrote a research proposal entitled - Morphology control and characterisation of organic and hybrid devices for thin-film electronics Recruited a PhD student Performing / directing the project
Collaborator Contribution Financial support of the project Participating in recruitment of a PhD student Contributing to the project including hosting a student in the company
Impact Industrial engagement in multi-disciplinary research (Chemistry, Materials, Physics and Engineering)
Start Year 2016
 
Description Industrial collaboration with NPL 
Organisation National Physical Laboratory (NPL)
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Academic/University 
PI Contribution Wrote a research proposal entitled - Controlling Microstructure of Organic & Hybrid Materials via Solution Processing Recruited a PhD student Performing / directing the project
Collaborator Contribution Financial support of the project Participating in a PhD student recruitment Contributing to the project via regular project review meetings Hosting a student at NPL for a short time
Impact Industrial engagement in multi-disciplinary research (Chemistry, Materials, Physics and Engineering)
Start Year 2014
 
Description Industrial collaboration with Samsung Electronics 
Organisation Samsung
Country Global 
Sector Private 
PI Contribution Wrote a research proposal - High-Performance Organic Near-IR Photodetectors via Advanced Molecular Structure Control and Analysis Performing / directing the project
Collaborator Contribution Financial support of the project Contributing to the project via regular project review meetings
Impact Industrial engagement in multi-disciplinary research (Chemistry, Materials, Physics and Engineering)
Start Year 2015
 
Description Public lecture 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact "Plastic Electronics - Next Generation Technology", Public Lecture at Institution of Engineering and Technology (IET), London (15 Sept 2015).
Year(s) Of Engagement Activity 2015
URL https://www.imperial.ac.uk/nanoanalysis-group/group-news/
 
Description UK-Korea Workshops on Plastic Electronics 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Organised the UK-Korea workshops on Plastic Electronics (PE).
Based on the strong interactions with Korean HEIs and Industry, the UK-Korea PE Consortium was formed (Dec 2013) involving more than 30 UK and Korea academic & industrial partners.
Year(s) Of Engagement Activity 2012,2013,2014,2015
URL http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/centres/plasticelectronics/newssummary...