Fullerene-free photovoltaic devices
Lead Research Organisation:
University of Sheffield
Department Name: Physics and Astronomy
Abstract
Non-fullerene acceptors have recently been used in polymer-blend photovoltaic devices to achieve power conversion efficiencies that now exceed 12%. In this project, the student will characterize a range of new acceptor materials synthesized or supplied by Ossila Ltd, and provide data regarding their optimized performance in both photovoltaic and transistor devices. This data will be used on Ossila's website, as part of the quality assurance of the materials and for content marketing of a series of new commercial products. The student will also undertake detailed characterization measurements of the nanostructure of polymer:acceptor films to understand the role of molecular morphology on device performance. The student will also explore the use of various coating techniques to deposit PV-applicable thin films.
| Description | The majority of work so far towards this award has been towards establishing the stability of classic non-fullerene acceptor ITIC. Organic photovoltaic solar cells have traditionally used fullerene based acceptors but these suffer from poor absorption of visible light and degradation when exposed to oxygen. Non-fullerene acceptors can theoretically overcome these issues and are usually viewed as more stable than fullerene based acceptors. Our work has shown that for ITIC, when compared to PCBM, this is not the case. Whilst both acceptors have poor stability with respect to oxygen and water, ITIC has significantly worse intrinsic morphological stability, and leads to devices degrading to below 20% of their original efficiency within 24 hours of illumination. The mechanisms of this degradation are currently under review and will be published within the next year. There have been several related findings revolving around the morphology and orientation of PBDB-T:ITIC thin films blends. |
| Exploitation Route | The degradation mechanisms of ITIC established by our work could be applied to other non-fullerene acceptors and used to improve organic photovoltaic stability in the future. |
| Sectors | Energy,Environment,Manufacturing, including Industrial Biotechology |