New Scientific Breakthrough: Organic Solar Cells Achieve Unprecedented Efficiency
A new scientific breakthrough.. Organic solar cells reach unprecedented efficiency
Researchers fromHong Kong Polytechnic UniversityHong Kong Polytechnic University were able to reach a set of organic solar cells (OSCs) to an astonishing “energy conversion efficiency” of 19.31%. Organic solar cells are known as polymer or plastic solar cells, and they are made of a polymer with the ability to absorb solar rays.
Power conversion efficiency or “power conversion efficiency” – which is called for short as (PCE) – is considered one of the very important measures for estimating the energy generated from a certain solar radiation. It also represents an important criterion for evaluating the performance of photovoltaic cells (PVs) or solar panels in generating energy, and it can be defined as the ratio between the total amount of energy absorbed/consumed by the cell and the amount of energy produced by it.
It is worth noting that the improved efficiency – more than 19% – at the hands of university researchers is considered a record for binary organic solar cells.
Led by Professor Li Gang, Professor and Head of the Department of Energy Conversion Technology, and Sir Sze Yun Zhong, Professor of Renewable Energy, the research team devised a new technique to regulate the morphology of organic solar cells, using 1,2,3-trichlorobenzene as a regulator of the crystallization process. This new technology further enhances the efficiency and stability of organic solar cells.
What are organic solar cells?
Unliketraditional solar cellswhich rely mainly on silicon as a semiconductor material, organic (polymer) solar cells rely on organic electronics instead of silicon to produce electricity.
As a result of the above, these cells are lightweight and highly flexible, compared to traditional solar cells. In addition to its light weight, it can be transparent. Which means it can be used in many applications, such as: windows, electronic devices, and others. In addition, these cells are easier and cheaper to manufacture and recycle.
In recent years, the obstacle to increasing reliance on this type of cell has been its instability and poor efficiency. However, the accelerated pace of research has greatly developed these cells, and this latest scientific breakthrough may have a contribution in shedding more light on this technology.
These cells are manufactured in their simplest form by placing a single layer of organic electronic materials between two metal conductors such as a sandwich. They can also be manufactured by placing two layers of organic electronic materials, and are then called binary organic solar cells.
The two layers in the last type consist of two materials with different electronegativity and ionization energy; Therefore, electrostatic energy is generated on the surface between them, and one of these two layers is called the Donor, while the other is known as the Acceptor. The organic electronics used are solution-processable, which explains the flexibility of these cells and low production costs.
Based on the above, both solutions of the two materials can mix heterogeneously, hence the name of bulk heterojunction polymer solar cells, which work by generating excitons by incident light, and this is followed by a separation of charges at the interface of the donor and the acceptor, which are mixed in the layer known as the active layer. These charges then move to the poles, where they flow out, and then come back again from the other side.
The properties of the active layer control the efficiency of the cell, and one of the most important of these properties is the recombination of charges after their return, as well as the movement of gaps in this layer of semiconducting materials.
Achieving greater efficiency with organic solar cells
The team developed a non-monotonic processing strategy to manipulate the morphology of heterogeneous organic solar cells, which simultaneously optimizes the crystallization dynamics and power loss in organic solar cells with non-fluorescent acceptors.
In contrast to the strategy of using traditional solvent additives – which rely on large accumulation of molecules in organic solar cells – the new method works by assembling more molecules in a suitable and more organized manner, which experimentally leads to significantly increasing the efficiency of organic solar cells and reducing the rate of non-radiative recombination losses. It is worth noting that non-radiative recombination reduces the efficiency of light generation and increases heat loss.
Professor Lee said: “The research challenges were the morphology of additive-based materials, which suffer from non-radiative recombination loss. Thus reducing the open circuit voltage. It took the research team about two years to develop a non-monotonic strategy to increase the efficiency of inorganic solar cells and reduce non-radiative recombination loss. There is no doubt that the publication of this research will increase the momentum around this promising type of solar cell.”
He added: “The new discovery will not only make organic solar cells an exciting field, but it will likely help create huge opportunities in applications such as: portable electronics, and building integrated photovoltaic cells; Because organic solar cells have properties such as: flexibility, transparency, and the possibility of coloring them in any color, in addition to the low cost of manufacturing them. “When the technology’s problems of cell instability and poor efficiency are addressed, it will become a sustainable option in many applications.”
It is worth noting that there was significant appreciation for Professor Lee’s efforts in scientific circles, as a distinguished researcher for 9 consecutive years, starting in 2014. This confirms his strong influence on global research, as his pioneering research on polymer solar cells since 2005 has helped make a sustainable impact on the development of printable solar energy technologies.
