What is Graphene?

Posted on Thu, Mar 15, 2018
As part of a joint collaboration, this article was written by Roni Peleg, Editor-in-Chief of Graphene-Info, the leading international graphene publication for over 9 years and visited by tens of thousands of professionals a month. Graphene-Info provide a multitude of services to the graphene market based on their extensive & up-to-date knowledge hub & close ties with industry leaders. 

Graphene is a 2D material made from carbon atoms that are arranged in a hexagonal pattern (a honeycomb crystal lattice). It is the basic building block of graphite, used in pencil tips, batteries and many other industrial applications.

Graphene is considered a “wonder material” since it has many remarkable properties: It is the thinnest material in the world (just one carbon atom thick), and also one of the strongest - much stronger than both diamond and steel of the same thickness. Graphene is also flexible and transparent, has an extraordinarily large surface area, and is an extremely stretchable crystal. Graphene is one of the best conductors of electricity ever found and is also an excellent thermal conductor. In addition, it has fascinating optical properties.

Scientists and researchers all over the world are vigorously working on finding ways to best use graphene, and while the industry is still very nascent, applications are starting to emerge. However, several issues must be addressed before graphene can live up to its potential and become the revolutionary material it is believed to be. Some of the issues include a lack of bandgap, cumbersome and expensive production and handling processes, among others.


New Guide Available: Sheet Resistance Measurements of Thin Films

Posted on Tue, Mar 13, 2018

An important characteristic of various materials, sheet resistance (a.k.a. surface resistivity) quantifies the ability for electric charges to move along uniform thin films. Knowing the sheet resistance of a material allows you to calculate its resistivity and conductivity - and thus enables you to electrically characterise the material.


Schematic diagram of a four-point probe circuit
Schematic diagram of a four-point probe circuit.


Four-point probes are the most common piece of equipment used to carry out this measurement. However, most four-point probes on the market use sharp needles as probes, which are likely to damage delicate thin films and reduce the accuracy of sheet resistance measurements. Ossila's Four-Point Probe overcomes this issue by using spring-loaded probes with round tips and a precision vertical translation micrometre-operated stage that ensures gentle, controlled contact with the thin-film.

In this guide, you will get a concise overview of the four-probe method, and learn how to take sheet resistance measurements of delicate thin films using the Ossila Four-Point Probe.


Now Available: High-performing Polymer Acceptors - PNDI(2HD)T & PNDI(2HD)2T

Posted on Tue, Mar 06, 2018

Having achieved 10% power conversion efficiencies (PCE), all-polymer solar cells (all-PSCs) have been the subject of significant research interest in recent years. With p-type polymers as electron donors and n-type polymers as electron acceptors, all-PSCs have contributed to the rise of high thermal, mechanical and photochemical device stability - with the prospect of large-area production. Unlike conventional polymer-fullerene solar cells, all-polymer OPVs have the potential to develop into a wider range of polymer materials; with the alteration of their chemical structures to adjust energy levels and film morphology for better device stability and efficiency. Unlike fullerenes, polymer acceptors cover a wider spectrum of visible light and have much higher absorption coefficients.

High-performing polymer donor materials have been intensively studied and well-developed. However, high-performing polymer acceptor materials are yet to be fully explored. Among them, polymer acceptors incorporated with imide-based repeating units (such as naphthalenediimide (NDI) and perylenediimide) are currently the most promising n-type polymer candidates. This is due to their great electron-transporting capabilities and higher electron affinities.


pndi(2hd)t, pndi(2HD)2t 


At Ossila, we aim to bring the most advanced and sophisticated materials to our customers. In addition to PNDI2(OD)2T and PNF222 that are already available from Ossila, we are now also providing you with PNDI(2HD)T and PNDI(2HD)2T, copolymers of naphtalene and bithiophene. PNDI(2HD)2T shows a higher degree of crystalline behaviours (that can promote 3D charge transport) compared to PNDI2(OD)2TPNDI(2HD)T exhibited a PCE of 6.64% with better flexibility, stretching, and bending properties when compared to polymer solar cells with PCBMs as acceptors.


  1. 9.0% power conversion efficiency from ternary all-polymer solar cells, Z. Li et al., Energy & Environ. Sci., 10, 2212-2221 (2017); DIO: 10.1039/C7EE01858D.
  2. All-Polymer Solar Cells Based on a Conjugated Polymer Containing Siloxane-Functionalized Side Chains with Efficiency over 10%, B. Fan et al., Adv. Mater., 29 (47), 1703906 (2017); DOI: 10.1002/adma.201703906
  3. Improved Performance of All-Polymer Solar Cells Enabled by Naphthodiperylenetetraimide-Based Polymer Acceptor, Y. Guo et al, Adv. Mater., 29 (26), 1700309 (2017); DOI: 10.1002/adma.201700309.
  4. Flexible, highly efficient all-polymer solar cells, T. Kim et al., Nat. Commun., 6, 8547 (2015); DOI: 10.1038/ncomms9547.

New Guide Available: Slot-Die Coating Theory, Design, & Applications

Posted on Tue, Feb 27, 2018

Ever since it was launched late last year, there has been an incredibly positive response to our Slot-Die Coater! Your feedback has contributed to giving us a better idea of where our customers' research interests lie. Therefore, we've worked to develop more content guides for Slot-Die Coating to help you with your research.


Slot-die menisci theory
In slot-die coating, upstream and downstream solution flow is determined by the interaction of the pressure gradient and the shear force at the substrate-liquid interface.


You can now access our guide to Slot-Die Coating Theory, Design, & Applications - a concise and detailed overview of slot-die coating as a deposition technique, the theory of the technique itself, along with practical tips and considerations that are needed when working with this technique.

A PhD Student Condenses (Vol. 4): Factors Influencing OPV Stability & Degradation

Posted on Fri, Feb 23, 2018
This is the fourth post in a monthly guest blog series titled "A PhD Student Condenses...", where the latest academic articles will be condensed and reviewed by one of Ossila's academic collaborators - Emma Spooner, a first-year PhD student the University of Sheffield. If you have any feedback or want to submit a topic request for future blogposts in this series, you may do so via this online form.
Emma Spooner | Ossila - University of Sheffield PhD Student

My name is Emma Spooner and I am currently pursuing a PhD in Fullerene-Free Photovoltaic Devices at the University of Sheffield, in collaboration with Ossila Ltd. As part of this collaboration, I will be running this monthly series where I review recent papers encountered in my research to provide a concise & helpful summary for Ossila’s customers.

For the fourth article in my series, I will be discussing the recent work by Rafique et al., entitled ‘Fundamentals of bulk heterojunction organic solar cells: An overview of stability/degradation issues and strategies for improvement’. A summary of the fundamental principles of solar cells can be found in this Ossila guide on solar cell theory & measurement, whilst this discussion will focus on factors influencing their stability and degradation.


Condensed Summary

Title:  Fundamentals of bulk heterojunction organic solar cells: An overview of stability/degradation issues and strategies for improvement.

Citation: S. Rafique et al., Renew. Sust. Energ. Rev. (84), 43-53 (2018).

DOI: 010.1016/j.rser.2017.12.008

Learning point: Bulk heterojunction organic solar cells are susceptible to a wide range of degradation mechanisms, including both obvious extrinsic factors, such as oxygen and humidity, and intrinsic factors. Encapsulation alone is not always sufficient to produce stable devices


Amruth's Slot-Die Secondment

Posted on Tue, Feb 20, 2018

As an industrial partner in the EU-funded Excilight Innovative Training Network (ITN) Programme, Ossila recently hosted Amruth, who is an Excilight PhD student. Amruth was on secondment with us from November 2017, and primarily worked with our Slot-Die Coater. As his secondment with Ossila drew to a close earlier this month, we thought it would be great for him to share his experiences and some of his research findings with you!


Excilight PhD student, Amruth, with his finished OLED device
Amruth with his finished OLED device.


What were you working on before joining Excilight?

I worked in the field of printed electronics for over 5 years, carrying out industrial R&D in India. However, I had a desire to conduct more innovative scientific research and publish academic articles, which is why I chose to pursue a PhD with the Excilight Training Network.



Photo & Caption Contest: Share Your Research Story!

Posted on Mon, Feb 12, 2018

Ossila are giving away 50 exclusive T-shirts & 5 x £50 Amazon UK vouchers!

To take part, all you need to do is:

1) Upload a photo of any Ossila equipment in your lab to Facebook and write a caption about how it helps you in your research!

2) Tag the Ossila Ltd Facebook page in your post & use the hashtag #OssilaGiveaway

3) After posting, follow the Ossila Ltd Facebook page (if you haven't already!)


Science in Industry: Interactive Workshop with EPSRC New & Sustainable PV CDT

Posted on Wed, Feb 07, 2018

Ossila is once again proud to provide industrial support for the Engineering & Physical Sciences Research Council's (EPSRC)  Centre for Doctoral Training in New & Sustainable Photovoltaics (CDT-PV). 

Continuing our annual tradition of running workshops with the new cohort of 1st-year PhD students, this marked our third consecutive year collaborating with the CDT-PV in hosting a training workshop (the previous two focused on Scientific Python coding). This year, our workshop was part of the CDT-PV's training on the commercialisation of science.


CDT-PV students getting a tour of an Ossila lab
CDT-PV students during the Ossila lab tour.


To start the day off, the CDT-PV were invited to the Ossila Headquarters for a introductory session and office tour, led by Dr. James Kingsley (Managing Director of Ossila). In the main office area, James explained the role of each individual department, and how they all worked cooperatively to contribute to the bigger picture of running a successful business. Following a quick laboratory tour, James conducted an interactive presentation on Ossila's history, mission, and philosophical values. 



New Slot-Die Coating Guide Available: Troubleshooting Defects

Posted on Thu, Jan 25, 2018

An extremely versatile deposition technique, slot-die coating is capable of being integrated into both roll-to-roll and sheet-to-sheet deposition systems. Slot-die coating's key advantage is its simple relationship between i) wet-film coating thickness, ii) the flow rate of solution, and iii) the speed of the coated substrate relative to the head. Moreover, it can achieve extremely uniform films across large areas - in the best cases with variation being less than 1% across several meters. 

Figure 1. The stable coating window for slot-die coating allows for defect-free films. By tuning processing parameters, it can be returned to the stable coating window.


However, despite the many advantages of slot-die coating, there are a few technical challenges that make it slightly more difficult compared to standard coating techniques (e.g. spin coating). These challenges arise from the need for pressure to be balanced at varying interfaces, so that the coating process can form a stable meniscus. Coating must be done within a stable window for it to be defect-free, and the variation of one of many parameters can steer the coating process away from this stable coating region.

Ossila have created a new guide to help you troubleshoot any slot-die coating issues you may face in your research. In this guide, we hope to introduce the idea behind the stable coating window that slot-die coating operates within, and relate this to observable defects that can occur within the film. By knowing how the processing window relates to coating parameters, it is possible to vary these to return to the stable processing region and remove defects from your coatings.



Official Announcement: Change of Address

Posted on Mon, Jan 22, 2018

This is an official announcement that Ossila will be moving to a new address!

Starting from the 27th of January 2018, our new address will be:

Ossila Ltd

Solpro Business Park

Windsor Street

Sheffield S4 7WB

United Kingdom


Please note that all other contact information will remain the same.

Phone: +44 (0) 114 2999 180

Fax: +44 (0) 800 098 8142


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