Stability of Organic Solar Cells based on Non-Fullerene Acceptors

Lead Research Organisation: CARDIFF UNIVERSITY
Department Name: Sch of Engineering

Abstract

Organic and other types of solution-processed solar cells are a highly promising alternative to conventional silicon-based photovoltaics (PV) as a lightweight, flexible, disposable and truly building-integrated PV technology with extremely quick energy payback. However, their limited stability has now been widely recognised as a common bottleneck for their commercialisation, with exposure to various environmental factors (e.g. light, heat, oxygen, humidity) leading to rapid losses of their performance, the origin of which often remains widely unclear.
Fullerenes have been ubiquitously used as an electron acceptor and transport material in organic solar cells (OSCs) in the past two decades. Only until the last 3-4 years, non-fullerene acceptor materials have been brought to the forefront of the development of OSCs as a more efficient, lower-cost and more versatile alternative to fullerenes, with the performance of fullerene-free OSCs already significantly exceeding that of fullerenes-based OSCs. Nevertheless, the majority of research efforts to date have only been dedicated to further optimising their efficiency, leaving a clear gap in the understanding of their stability and degradation mechanisms, another key consideration for their commercialisation.
This proposal is designed to address three very important yet largely unanswered questions in the development of stable fullerene-free OSCs: 1-What are the mechanisms causing the degradation of fullerene-free OSCs; 2-Can we understand these degradation mechanisms both comprehensively and quantitatively; and 3-What controls these degradation mechanisms and how to address them? To answer these questions, this proposal will develop a new research methodology to study OSC degradation, which has not been established previously. By performing time-resolved and inter-correlated optical, structural and functional analysis of PV films and devices degraded in a locally-controlled environment, this methodology is capable of capturing the real-time information of the fundamental processes leading to device performance losses during the degradation process, thereby establishing a quantitative relationship between the degradation mechanisms and the resulting OSC degradation behaviour. Specifically, the evolution (i.e. time-resolved) of several advanced, performance-determining device parameters, as well as that of chemical and structural changes during the same degradation process (i.e. inter-correlated), will be recorded and further analysed in order to reconstruct the OSC degradation behaviour. Only fullerene-free OSCs will be studied in this project, but the new methodology can be universally applied to study other types of solar cells, such as polymer:fullerene, quantum dots, dye-sensitised and perovskite solar cells. A core focus of this project is the quantitative analysis of the impacts of major degradation mechanisms of fullerene-free OSCs as a function of their material and device design. The PI has already led the research efforts in quantitatively investigating the degradation of fullerenes and their impacts upon OSC stability, which laid the foundations for the development of the new research methodology proposed here. Based on the quantitative knowledge acquired, this proposal also aims to develop comprehensive material and device design rules capable of guiding the systematic optimisation of the stability of fullerene-free OSCs.
This proposal will build upon the established research expertise and facilities in energy materials and devices at Cardiff University, in close collaboration with Swansea University and Imperial College London. The project will be carried out in partnership with 1) Eight19 Ltd., a UK-based SME specialising in the commercialisation of OSC products; 2) NSG group, a UK-based, world-leading company in glass and glazing products (e.g. glass-based PV products) 3) Armor group, a France-based company specialising in printing and coating technologies.

Planned Impact

This proposal is aligned with EPSRC's priority areas of Solar, Functional materials and Materials characterisation, and will contribute to the development of the UK as a more productive nation and a more resilient nation. The timeliness of this proposal is aligned with EPSRC's sustain investment on Solar Technology and growing investment on Materials for Energy Applications.The successful delivery of this project will lead to the design and manufacture of more stable fullerene-free organic solar cells (OSCs) and solar modules, thereby paving the way for their commercialisation and contributing to addressing the grand challenge of "clean growth" set by the UK's industrial strategy.
The research outcomes of the project will generate direct impact upon the industrial collaborators, Eight19 Ltd., NSG group and Armor Group. These companies have all identified stability as a major bottleneck for the commercialisation of their PV products, and are investing substantially in related R&D activities. These companies will contribute to this project by supplying industrial-level fullerene-free organic PV modules for stability evaluation and advanced characterisation (Eigh19 and NSG), development of fully-printed OSC products on flexible substrates (Eigh19), development of glass-based OSC products particularly for semi-transparent PV applications (NSG), hosting research visits to the project team members (Eight19 and NSG) and also by allocating the time of a number of their technical experts (all companies). The research outcomes of the project (e.g. new material and device designs, new processing routes) will be evaluated in terms of industrial impacts and will be implemented into the companies' manufacturing processes. Extensive research collaborations and knowledge exchange will be enabled through academic/industrial secondments and research visits of the project team members and company experts, and project progress will be updated on regular project collaborator meetings (held quarterly).
In addition to the companies above, other companies specialising in printed photovoltaics, including Heliatek, OPVIUS (former BELECTRIC OPV), CSEM and Oxford PV, are also potential beneficiaries of this project. The research outcomes of this project will not only help these companies to gain an in-depth understanding of the degradation mechanisms, but also to improve the design of their PV products for better stability.
This proposal will be strongly complementary to the established research activities in the UK and abroad in the development and applications of printed optoelectronic materials and devices (e.g. organic, dye-sensitised, perovskite and quantum dot solar cells, transistors, photodetectors and light-emitting diodes), thereby generating immediate impact on a range of research programs including material and device engineering, advanced characterisation, structure-function analysis, device physics and modelling. In addition, the research team members employed in this project will be equipped with skills and knowledge in printed optoelectronic materials and devices, thereby enhancing their future employability in related academic or industrial fields.

Publications

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Liu H (2022) Semi-Planar Non-Fullerene Molecules Enhance the Durability of Flexible Perovskite Solar Cells. in Advanced science (Weinheim, Baden-Wurttemberg, Germany)

 
Description We have investigated a number of high performance fullerene-free organic photovoltaic systems and found that their photostability is strongly related to the molecular design of the acceptor molecules, particularly linked to their molecular conformation. This opens up the way of enhancing the device lifetimes and control of the degradation mechanisms of organic solar cells through optimisation of the moecular structure of non-fullerene acceptors;

We have identified that some emrging non-fullerene acceptor molecules can chemical react with conventional device interlayers such as PEDOT:PSS, mediated by their volatile end groups. This paves the way to the development of novel device interlayers to address this degradation pathway towad enhanced solar cell lifetimes.

We have initiated offical partnerships with the EPSRC funded ATIP project at Swansea University, undertaking PV stability research which will significantly benefit the successful delivery of ATIP.

We found that some non-fullerene acceptors like Y6 can also be used as an interlayer material to replace fullerenes and achieve improved device performance and stability of perovskite solar cells.

The findings of the project has led to a number of invited jounal submissions (e.g. SolarRRL, Aggregates, Advanced Energy Materials) and an invited talk at the NanoGe Spring meeting.
Exploitation Route Academically, the research outcomes will be taken forward by researchers of the PI's network and beyond (including UK and overseas) as publications and conference presentations.

Economically, the new research outcomes will bring know-how in the development of new industrial level PV modules to the project's industrial partners such as NSG and Armor.
Sectors Energy

Manufacturing

including Industrial Biotechology

 
Description We have discoverd several key degradation mechanisms involved in the materials and device components of organic solar cells. These findings have been communicated to our relevant industrial partneters, which may be used to develop new products with improved performance.Follow-on onsite experiments and research secondments to some industrial partners have been planned. A number of companies (NSG, SOULE) are involved in an ongoing research project funded by Queen Mary Impact FUnd project. PolySolar and NSG have agreed to join an future grant application.
First Year Of Impact 2023
Sector Construction,Electronics,Energy
Impact Types Economic

 
Description AXA postdoctoral research fellowship
Amount € 116,000 (EUR)
Organisation AXA 
Sector Private
Country France
Start 04/2022 
End 05/2024
 
Description International Exchange Scheme 2022
Amount £12,000 (GBP)
Organisation The Royal Society 
Sector Charity/Non Profit
Country United Kingdom
Start 01/2022 
End 12/2023
 
Description Repairable halide perovskites for sustainable next generation photovoltaics
Amount € 236,000 (EUR)
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 08/2024 
End 09/2026
 
Description thErmal cycLing stAble perovSkite photovolTaIC (ELASTIC)
Amount € 190,000 (EUR)
Organisation Marie Sklodowska-Curie Actions 
Sector Charity/Non Profit
Country Global
Start 08/2025 
End 09/2027
 
Description EPFL-QMUL collaboration 
Organisation Swiss Federal Institute of Technology in Lausanne (EPFL)
Country Switzerland 
Sector Public 
PI Contribution We have provided novel material samples and guidance on processing routes.
Collaborator Contribution EPFL fabricated high performance perovskite solar cells and validate the performance and stability of the novel device designs
Impact We have initiated a collaboration to explore a range of promising non-fullerene small organic molecules for use as electron transport layers in perovskite solar cells. Zuhong Zhang, Zhenhuang Su, Guixiang Li, Jing Li, Mahmoud H Aldamasy, Jiaxin Wu, Chenyue Wang, Zhe Li, Xingyu Gao, Meng Li, Antonio Abate, Improved Air Stability of Tin Halide Perovskite Solar Cells by an N-Type Active Moisture Barrier, Advanced Functional Materials, 34, 2306458 (2023)
Start Year 2023
 
Description HZB 
Organisation Helmholtz Association of German Research Centres
Department Helmholtz-Zentrum Berlin for Materials and Energy
Country Germany 
Sector Academic/University 
PI Contribution We have estalished new collaborations with research group led by Prof Antonio Abate on the research into perovskite solar cells. We have engaged with this collaborator in fruitful results discussion in the stability studies of perovskite solar cells, and offered on-site measurements of their samples.
Collaborator Contribution We were invited to join a number of research projects led by HZB Berlin, and strenthed research collaboration with them through engagement of several ongoing research projects.
Impact Science 379 (6630), 399-403 Advanced Energy Materials 12 (48), 2202887 ACS Energy Letters 7 (12), 4451-4458
Start Year 2022
 
Description Henan University 
Organisation Henan University
Country China 
Sector Academic/University 
PI Contribution regular project discussion, joint experiment, access to data
Collaborator Contribution regular project discussion, joint experiment, access to data, use of research facilities
Impact Semi-Planar Non-Fullerene Molecules Enhance the Durability of Flexible Perovskite Solar Cells
Start Year 2021
 
Description Imperial College London 
Organisation Imperial College London
Department Department of Chemistry
Country United Kingdom 
Sector Academic/University 
PI Contribution Working closely with academic group of the Centre for Plastic Electronics, my research group has established new research areas on photovolaic stability.
Collaborator Contribution My partners will offer access to related PV research facilities, provide helpful discussions on project progress, and relevant research samples.
Impact Yiwen Wang, Jinho Lee, Xueyan Hou, Chiara Labanti, Jun Yan, Eva Mazzolini, Amber Parhar, Jenny Nelson, Ji-Seon Kim, Zhe Li; Recent Progress and Challenges toward Highly Stable Nonfullerene Acceptor-Based Organic Solar Cells, Advanced Energy Materials , 11, 2003002, 2021 Bo Hou, Byung-Sung Kim, Harrison Ka Hin Lee, Yuljae Cho, Paul Giraud, Mengxia Liu, Jingchao Zhang, Matthew L Davies, James R Durrant, Wing Chung Tsoi, Zhe Li, Stoichko D Dimitrov, Jung Inn Sohn, SeungNam Cha, Jong Min Kim; Multiphoton Absorption Stimulated Metal Chalcogenide Quantum Dot Solar Cells under Ambient and Concentrated Irradiance; Advanced Functional Materials, 30, 2004563, 2020
Start Year 2021
 
Description PolySolar 
Organisation Polysolar
Country United Kingdom 
Sector Private 
PI Contribution Our results has attracted interest from PolySolar in the development of stable semitransparent solar cells for solar windows and PV powered building structures
Collaborator Contribution The parter has agreed to support a follow up grant proposal applications and provide in-kind support in the region of ~£20k
Impact The parter has agreed to support a follow up grant proposal applications and provide in-kind support in the region of ~£20k We have included this collaboration for a joint grant application to EPSRC in March 2023, which was not funded. We are currently preparing a further grant proposal with PolySolar a project partner, which will be submitted in 2024.
Start Year 2023
 
Description QMUL-NSG partnership 
Organisation NSG Nippon Sheet Glass Pilkington
Country Japan 
Sector Private 
PI Contribution We have developed high performance semi-transparent organic solar cells for glaze based applications in building exteriors, which attracted NSG's interest in potential commercial exploitation
Collaborator Contribution NSG invited the Zhe Li to visit their glass manufacturing line and advanced coating facilities and initiated several discussions for potential project collaborations. NSG has agreed to provide various types of glass substrate for QMUL researchers to fabricate PV devices on. NSG was involved in several Queen Mary Impact fund applications aiming to commercialise our technology. NSG has supported an EPSRC grant application in 2023 (not funded) providing £50k in in-kind contribution
Impact NSG invited the Zhe Li to visit their glass manufacturing line and advanced coating facilities and initiated several discussions for potential project collaborations. NSG was involved in several Queen Mary Impact fund applications aiming to commercialise our technology. NSG has supported an EPSRC grant application in 2023 (not funded) providing £50k in in-kind contribution
Start Year 2023
 
Description Queen Mary University of London - Oxford University collaboration on semi-transparent organic solar cells 
Organisation University of Oxford
Country United Kingdom 
Sector Academic/University 
PI Contribution We have worked with colleagues of University of Oxford to development high performance semi-transparent organic solar cells. Eva Mazzolini from QMUL has travelled to Oxford to undertake device fabrication and testing studies at Prof Henry Snaith's group at University of Oxford.
Collaborator Contribution We have worked with colleagues of University of Oxford to development high performance semi-transparent organic solar cells. Prof Henry Snaith's group at University of Oxford supported Eva Mazzolini on the fabrication of high performance organic solar cells based on sputters transparent conductive oxide as electrodes.
Impact A joint publication is under development and expected to be submitted in 2024.
Start Year 2023
 
Description Swansea University 
Organisation Swansea University
Department College of Engineering
Country United Kingdom 
Sector Academic/University 
PI Contribution Partnership with academics at the SPECIFIC IKC and College of Engineering on the upscaling, stability and characterisation of solution processed semiconductor materials and devices, especially through the ATIP project.
Collaborator Contribution Provision of relevant PV research facilities (PV upsclaing, advanced characterisation), regular discussions, and collaborations with ATIP project's partners on PV stability related research activities.
Impact p-Conjugated small molecules enable efficient perovskite growth and charge-extraction for high-performance photovoltaic devices; Hui Liu, Hai-Rui Liu, Feng Yang, Ji-En Yang, Jian Song, Meng Li, Zhe Li, Wing Chung Tsoi, Martin Chinweokwu Eze, Zhi-Yong Liu, Heng Ma, Min Gao, Zhao-Kui Wang; cJournal of Power Sources; 448, 227420, 2021 Xueyan Hou, Yiwen Wang, Harrison Ka Hin Lee, Ram Datt, Nicolas Uslar Miano, Dong Yan, Meng Li, Furong Zhu, Bo Hou, Wing Chung Tsoi, Zhe Li; Indoor application of emerging photovoltaics-progress, challenges and perspectives; Journal of Materials Chemistry A; 8, 21503-21525 , 2020 Amirah Way, Joel Luke, Alex D Evans, Zhe Li, Ji-Seon Kim, James R Durrant, Harrison Ka Hin Lee, Wing C Tsoi; Fluorine doped tin oxide as an alternative of indium tin oxide for bottom electrode of semi-transparent organic photovoltaic devices; AIP Advances, 9, 085220, 2019
Start Year 2021
 
Description Université de Mons 
Organisation University of Mons
Country Belgium 
Sector Academic/University 
PI Contribution We have invited Prof Beljonne to join our project on OPV stability, who has provided strong support in the molecular simulation work. This collaboration has resulted in the acceptance of our work in Joule (Impact factor ~41), Cell's flagship journal in Energy.
Collaborator Contribution The group of Prof Beljonne has generated significant new results providing a comprehensive understanding of the molecular origin of the work.
Impact Yiwen Wang1, Joel Luke2, Alberto Privitera3, Nicolas Rolland4, Chiara Labanti2, Giacomo Londi5, Vincent Lemaur4, Daniel T. W. Toolan6, Alexander J. Sneyd7, Soyeong Jeong8, Deping Qian8, Yoann Olivier5, Lorenzo Sorace3, Ji-Seon Kim2, David Beljonne4, Zhe Li1* and Alexander J. Gillett7*., The critical role of the donor polymer in the stability of high-performance non-fullerene acceptor organic solar cells, Joule, accepted 2023
Start Year 2022
 
Description ATIP engagement award to host a science festival booth 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact We have been awarded £2000 to host a public engagement event. This is expected to be help in summer of 2024.
Year(s) Of Engagement Activity 2024
 
Description Industrial liaison forum events 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Annually held industrial event at Queen Mary with over 20 national companies attendence. The project team has showcased our findings at this event by delivering posters or presentations.
Year(s) Of Engagement Activity 2021,2022,2023
 
Description Industrial workgroup 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact We have grown significant research collaboration networks with a range of UK stake holders including NSG, PolySolar, Armor, Tata Steel, Soule Technologies, Poweroll. We have discussed about the business needs of these companies, and developed collaboraiton plans and engagement activties. Some partnerts are involved in an ongoing research project, and some has joined a recent research grant application.
Year(s) Of Engagement Activity 2022,2023