Soft Matter and Biological Physics group – Sheffield

It’s wonderful to see the fantastic series of papers published by our former group member, Dr. Rachel Kilbride, now based at the ESRF in Grenoble, France. During her PhD, Rachel focused on the study of organic solar cell blends using both neutron and X-ray scattering techniques, with a strong emphasis on stability and morphological changes. She worked closely with Dr. Emma Spooner—who was also at the University of Sheffield at the time, completing her PhD under the supervision of Prof. David Lidzey— Emma now works at the University of Manchester.

The first paper (link here – https://onlinelibrary.wiley.com/doi/full/10.1002/smll.202311109 ) investigates how solvent additives influence the nanomorphology and stability of organic solar cell blends, comparing fullerene- and nonfullerene-based systems. Using small angle neutron scattering (SANS), the team studied films processed with DIO and tracked their structural evolution over time. To enable this, a deuterated NFA material (ITIC-d52) was synthesized in collaboration with Dr. Ana Charas and Dr. Gabriel Bernardo. The results show that DIO induces more pronounced phase separation in NFA systems, and that both systems exhibit domain coarsening after long-term aging.

The second (link here – https://pubs.acs.org/doi/full/10.1021/acsaem.4c01272 ) focuses on improving the photostability of organic solar cell blend films, a key factor for long-term device performance. By comparing blends of PBDB-T with either PC₇₁BM or ITIC, the study reveals that the solvent additive DIO has very different effects on morphology and stability. Notably, DIO is retained about 10 times more in ITIC-based films. While high DIO levels reduce stability in encapsulated ITIC devices, the presence of oxygen surprisingly reverses this effect—DIO actually enhances device lifetime. With 3% DIO, the operational lifetime (T80) of ITIC-based devices doubles, indicating that DIO-induced morphological changes may mitigate photo-oxidative degradation.

The third and most recent (link here – https://pubs.acs.org/doi/abs/10.1021/acsami.5c04713) paper examines how vertical segregation within organic solar cell films affects device performance and stability. Using neutron reflectivity, the study compares PBDB-T:PC₇₁BM and PBDB-T:ITIC blends processed with varying amounts of DIO. Both systems show acceptor enrichment at the hole transport layer interface, but this effect is significantly stronger in ITIC-based films, where nearly pure ITIC accumulates. Increased DIO levels intensify segregation, especially in ITIC systems, leading to broader interfaces and morphological imbalance. Simulations reveal that this extreme segregation can cause nonideal ‘S-shaped’ JV curves and contribute to long-term device degradation. These findings underscore the importance of controlling vertical composition to ensure both immediate performance and lasting stability.

We have recently returned from an all too brief trip to the Institute of Physics – Physical Aspects of Polymer Science meeting. On the left is Joe Orgill, myself in the middle (Dr Andy Parnell) and Francis Gurman on the right. We all three of us had talks and it was truly a fantastic meeting both scientifically and socially. Thanks so much to the organising committee for making it such a success !

Our recent paper has just been publsihed in Nature Communications. A fantastic collaborative piece of work with my fantastic colleague Dr Nicola Nadeau, but primarily due to the amazing hard work and dedication of Dr Victoria Lloyd.

Our work on antibacterial surfaces is starting to appear. The first output is a comprehensive review of the “known knowns” or so we thought. Anyway it highlights the fact that there is still plenty of work to be done to truly undertand how to produce surfaces that mechanically kill bacteria in a rationally optimised way.

This has been a fantastic collaborative piece of science with my colleague Dr Rebecca Corrigan and our joint student now Dr Tom Catley.

Link to the paper

Its fantastic to see that the fantastic Harvesting Light fly through / artwork has breached the 100,000 online views mark. This is a real testament to the vision of Paul Evans and my former colleagues Richard Jones FRS and Mike Weir. But of course this was made possible by the amazing team at Human studios, who are a truly fantastic to work with.

Our recent paper has just been published in the ACS journal Chemistry of Materials. This work was a collaboration between Sheffield and TU Delft (with another Dr Parnell). The work was initiated by my colleague Mary O’Kane, a CDT PhD student in the Physics Department at Sheffield. It has been really very rewarding working with Mary and hopefully we have helped to dispel some of the dogma that exists at to what happens in solution prior to film formation.

It’s been a while but this was one of our first in person experiments back at the Diamond Light Source in Oxfordshire. Really exciting to be working back at a synchrotron.

Thanks so much to Frane Babarovic for his boundless enthusiasm and his old school analogue camera (Canon AE1 and 50mm lens) for the photos he took of the experiment.

You can see Dr Andy Parnell and Paul Evans discussing their long term Science-Art collaboration and talking through the visuals that they have co-created alongside working with Human studio. This forms part of the hugely influential Off the Shelf literary festival

https://player.sheffield.ac.uk/events/sciart-very-big-and-very-small

A paper on bringing ptyochography to the masses has just been published. This work involved Myself and Dr Sasha Mykhaylyk from Sheffield alongside a team from Diamond Light Source and some talented young scientists from the University of Ghent. The team from Diamond was Dr Darren Batey and Dr Silvia Cipicia (now at UCL).

The paper can be found here. The work was featured as a highlight in PRL and also on the Diamond Light Source website