Renewable energy: new perspectives for photovoltaic cells

New study on a critical mechanism for organic photovoltaic cell efficiency

In the future, photovoltaic cells could be worn on clothes, placed in cars or on umbrellas at the beach.

These are just some of the possible developments of a study just published in Nature Communications by researchers from Politecnico di Milano’s Physics Department, in partnership with colleagues from the University of Erlangen-Nuremberg and Imperial College London.

The research authors include Franco Valduga de Almeida Camargo, of the Institute of Photonics and Nanotechnology (IFN-CNR) and Professor Giulio Cerullo, focused on photovoltaic cells made using flexible organic technology. The most common photovoltaic cells based on silicon technology are rigid and require sophisticated and costly infrastructures to manufacture them. They also have high disposal costs.

An alternative future silicon replacement are “plastic” solar cells, which use two organic semiconductors, one electron donor and an electron acceptor, which absorb light energy and convert it into electricity.

Using organic molecules has several advantages, such as simpler technology, reduced production and disposal costs, mechanical flexibility and access to the chemical diversity associated with organic materials. However, Organic materials have much more complex physics than crystalline inorganic materials (such as silicon), particularly for charge transfer processes at donor-acceptor interfaces, which cause efficiency losses.

After four years of work, the researchers succeeded in creating solar cells with new materials in which losses due to interface states are minimised. By studying these materials with ultra-short laser pulses, they identified the physical reasons for this exceptional performance and have developed an optimisation model that is valid for other material combinations.

In the future, photovoltaic cells made from organic technology will be a cheaper source of energy with less environmental impact. And because of their mechanical flexibility, they can be incorporated into various everyday objects such as windows, cars, or even clothes and coats.

One of the challenges for humanity’s future is the development of clean and renewable energy sources. Sunlight provides the Earth with more than a hundred times more energy daily than humanity needs, making photovoltaic technologies among the most promising for the future. Italy, with to its climate, has one of the largest photovoltaic potentials in Europe, comparable to that of non-desert tropical countries.

For more information

Gasparini, N., Camargo, F.V.A., Frühwald, S. et al.
Adjusting the energy of interfacial states in organic photovoltaics for maximum efficiency.
Nat Commun 12, 1772 (2021).
The study online