Investigating Solar Energy – Examining the microstructure of Organic Solar Cells

“It’s been great having Mohamed as part of our team in Oxford. Such exchanges are essential if we want to solve global challenges like climate change. Among other benefits, they foster collaboration, create lasting networks and enrich the perspectives of everyone involved.”

Prof. Dr. Moritz Riede, University of Oxford, UK 

Improving Organic Solar Cell performance for energy production 

My name is Mohamed Emad Barhouma Elsayed Abdelaal and I am an Energy Materials research scientist at the Faculty of Engineering, Ain Shams University in Cairo, Egypt.  My research involves examining the micro-structure of Organic Solar Cells (OSC’s) to monitor how the performance of the cells is affected by their micro-structure under different environmental conditions. The aim is to improve the performance of Solar Cells for energy production by controlling their micro-structure and thereby to improve their benefit for alternative energy supply and pollution reduction measures.  

As the demand on the world’s classical energy resources such as petroleum products and natural gas are increasing, we must find alternative energy resources. In Egypt, for example, the government has set renewable energy targets of 20% of the electricity mix by 2022 and 42% by 2035¹. Egypt is therefore investing a lot of money in massive solar farms like the Benban project in Aswan and other solar energy projects. If the efficiency of OSC’s is improved through the research being conducted, then countries like Egypt might invest in more new Solar farms. In addition, since the OSC’s can be made semi-transparent and flexible, they can be installed on the glass on buildings in crowded cities like Cairo. 

Organic Solar cells are made of organic chemical materials, while traditional solar cells are made of inorganic materials, mainly silicon. OSC’s can be made semi-transparent, flexible and potentially cheaper than Inorganic Solar Cells (ISC’s), which are opaque and generally not flexible. However, ISC’s currently have a better performance and longer lifetime compared with OSC’s. Therefore, scientists are working on improving OSC’s because of their high potential to offer cheaper and more flexible energy options².  

Building my scientific network through GCRF START  

“North-South intercultural and interdisciplinary academic exchange between the University of Oxford and Ain Shams University is of particular benefit between these two well-established universities. Mohamed, our mutual student in the GCRF START project, co-supervised by Prof. Riede and I, has benefited from the exposure to a new academic environment and the exchange of ideas and expertise.”

Prof. Dr. Ghada Bassioni, Ain Shams University, Cairo, Egypt 

This research involves international collaboration which has been encouraged and assisted by GCRF START.  One of my research supervisors, Prof. Dr Ghada Bassioni, introduced me to the opportunities offered by START as an Energy Materials researcher. I have not only been able to attend conferences and workshops to further my knowledge and skills, providing great exposure and opportunities to build our scientific network, START has given me with access to world class facilities, equipment and devices to conduct my experiments. I collaborate with Prof. Moritz Riede’s group AFMD group in the Department of Physics at the University of Oxford and some of my experiments have been undertaken there, and at the UK’s national synchrotron – Diamond Light Source.  

Shining light on OSC microstructure  

I simulate the way the molecular components of Organic Solar Cell (OSC) organise themselves (the microstructure) in devices using a molecular dynamics simulations program similar to the procedure published by T. Lee et al. ACS Applied Materials & Interfaces 10, 32413 (2018). The simulations can be likened to real OSC materials ‘in situ’ and ‘ex situ’ to compare and validate the results achieved in simulation. We use a technique called X-ray diffraction which enables us to study surfaces and interfaces on an atomic scale and the micro-structure and interface evolution in real-time under vacuum conditions. 

To examine the microstructure of the OSC during evaporation, different tests are done including X-ray diffraction in the MINERVA chamber on the high resolution Beamline I07 at Diamond (Fig. 1&2) This involves evaporating the materials which make up the OSC onto a device surface (substrate) under X-ray illumination, allowing X-ray diffraction images to be collected ‘in situ’ as the materials are deposited. In this way, we can observe how the molecules change in their molecular packing (microstructure) over time as they land on the substrate microstructure. The MINERVA chamber also enables us to study how the microstructure changes in response to different environmental factors, such as temperature, humidity, and various gases. Sometimes, however, we evaporate the OSC’s at the University of Oxford using the Vacuum Evaporator (ECHO1) facility with the AFMD group, after which we examine the samples at Diamond using the X-ray diffraction process. In this case we don’t use MINERVA and the process of examination is called ‘ex situ’.  

Building OSC’s and molecular dynamics simulation of OSC microstructure 

Building the OSC’s themselves is done using ‘ECHO1’, a vacuum deposition chamber at the University of Oxford. The needed materials are supplied in solid state commercially or from collaborators. The organic materials are evaporated onto a glass substrate and the layer thickness of the Solar Cell is subsequently monitored through the evaporation rate and the length of time of evaporation. Co-evaporation is also possible, which allows the evaporation of more than one organic material at the same. After achieving the required thickness, the Solar Cell is cooled down and then encapsulated inside a nitrogen filled box under inert conditions, the solar cell is ready for further examination.   

I started conducting my research in September 2018 and before the end of my second year, I hope to publish my first paper. During the course of my research, I personally believe that every step forward is a huge achievement, without which we would never be able to proceed further. One achievement worth mentioning is that, with Prof. Dr. Moritz Riede support, I have learned molecular dynamics simulation of the micro-structure of OSC’s. I also learned how to write scripts and although they are basic and simple, they automate the simulation which reduces the time loss between simulation steps.  Every time the simulation is completed successfully, I feel so happy and proud that I have learned something new. 

GCRF START fostering global partnerships and internationalisation  

Commenting on the importance of international partnerships such as GCRF START for students like Mohamed, Prof. Dr. Ghada Bassioni, Professor of Chemistry and Head of the Chemistry Division at the Faculty of Engineering at Ain Shams University, said, 

“Overall, the openness for African, and especially Egyptian universities to internationalisation is growing rapidly, with unhindered communication channels and inexpensive travel. Global partnerships and fostering relationships with other institutions whether on an individual or institutional basis are the main source for international students and academic exchange. International students increase social and cultural diversity, enrich the research and learning environment and help local students to develop internationally relevant skills. There are a lot of benefits for seeking an international academic environment, whether it is to develop new ideas or tap into new sources of funding or to gain access to specialised equipment. As a result of the expansion of communication methods and the ease of international travel, one in five of the world’s scientific papers are co-authored internationally.” 

Read more here about the openness for African universities to internationalisation 

Learn more about Solar energy here and the differences between Organic and Inorganic Solar Cells here  

Read more here about the UN Sustainable Development Goal 7 for Energy 

Mohamed Abdelaal profile page here. 

Footnotes:

¹ IRENA (2018), Renewable Energy Outlook: Egypt, International Renewable Energy Agency, Abu Dhabi 

² Organic Solar Cell Materials toward Commercialization; Rongming Xue, Jingwen Zhang, Yaowen Li,* and Yongfang Li  DOI: 10.1002/smll.201801793