PolyU researchers achieved a record efficiency with organic solar cells

The research team developed a novel OSC morphology-regulating technique using 1,3,5-trichlorobenzene.

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Researchers at The Hong Kong Polytechnic University (PolyU) have used organic solar cells (OSCs), sometimes referred to as polymer solar cells, to reach a ground-breaking power-conversion efficiency (PCE) of 19.31%.

This remarkable binary OSC efficiency, which has one donor and one acceptor in the photo-active layer, is a first for binary OSCs.

The applications of these cutting-edge solar energy gadgets will be improved by their exceptional binary OSC efficiency.

An important benchmark for the efficiency of photovoltaics (PVs), or solar panels, in power generation is the PCE, a measurement of the power produced from specific sun irradiation. The PolyU researchers were able to increase efficiency by almost 19%.

The research team developed a novel OSC morphology-regulating approach employing 1,3,5-trichlorobenzene as a crystallization regulator under Prof. LI Gang, the Sir Sze-Yen Chung Endowed Professor in Renewable Energy at PolyU.The efficiency and stability of OSC are improved by this innovative method.

To manage the bulk-heterojunction (BHJ) OS shape and simultaneously optimize the crystallization dynamics and energy loss of non-fullerene OSCs, they created a non-monotonic intermediated state manipulation (ISM) technique. 

The ISM technique promotes the production of more ordered molecule stacking and favorable molecular aggregation, in contrast to the standard solvent additive strategy, which is based on excessive molecular collection in films.

The unwanted non-radiative recombination loss was decreased while the PCE was significantly raised.

Non-radiative recombination causes an increase in heat loss and a decrease in light-generating efficiency.

Converting solar energy to electricity is an important technique for creating a sustainable environment. Although OSCs are effective solar energy harvesting devices that show promise, their efficiency needs to be increased if they are to be widely adopted in real-world uses.

Prof. Li said, “The new finding will make OSC research an exciting field, which will likely create tremendous opportunities in applications like portable electronics and building-integrated PVs.”

The new door will open once affordable single-junction OSCs reach a PCE of over 20%, in addition to more reliable performance and other distinctive benefits like flexibility, transparency, stretchability, low weight, and tuneable color.

A non-monotonic ISM technique for improving OSC efficiency and reducing non-radiative recombination loss took Prof. Li’s research team two years to develop. 

The discovery will make OSC research attractive, and this will likely open up many options in areas like building-integrated PVs and portable electronics.

Since 2014, Prof. Li has been recognized as a Highly Cited Researcher nine times in a row for his innovative contributions to the study of polymer solar cells.

In a binary OSC with a PCE of more than 19%, his most recent study demonstrates a record-low non-radiative recombination loss of 0.168 eV. This is a positive outcome of his extensive research on OSCs over the past 20 years, and it will accelerate the adoption of solar energy.

Journal Reference:

  1. Fu, J., Fong, P. W., Liu, H., Huang,etal. A non-monotonic intermediate state transition enabled 19.31% binary organic solar cell and low non-radiative recombination. Nature Communications. DOI: 10.1038/s41467-023-37526-5