Introducing high-performance non-fullerene organic solar cells

August 30, 2018

Organic solar cells (OSCs) has driven their efficiencies to above 10% to reach a viable level for commercialization. However, the increase in the photoactive layer thickness has resulted in lower efficiency levels, which therefore brings much complex manufacturing process.

A research team, led by Professor Changduk Yang and his research team in the School of Energy and Chemical Engineering at UNIST, has introduced a novel method that can solve issues associated with the thickness of the photoactive layers in OSCs.

In the study, the research team has succeeded in obtaining an efficiency of 12.01% in the organic solar cells, using a non-fullerance acceptor (IDIC) in the photoactive layer. Moreover, the new photoactive layer maintained its initial efficiency, even when the maximum measured thickness being in the range of 300 nm. This will help accelerate the design process, as well as the further commercialization of OSCs.

"Photoactive layers in the existing OSCs are rather thin (100 nm), and therefore it has been impossible to handle them via large-area printing process," says Professor Yang. "The new photoactive layer maintained its initial efficiency, even when the maximum measured thickness being in the range of 300 nm."

Conventional solar cells are inorganic solar cells that are made of silicon (Si) semiconductors. While these solar cells are highly efficient and stable, they are inflexible and expensive, thus challenging to produce. Therefore, in recent years, lightweight organic solar cells (OSCs) and perovskite solar cells have gained much attention as the promising candidates for next-generation solar cells.

Although OSCs do exhibit high stability and reproducibility, the efficiency level of OSCs is not nearly as high as that of the perovskite solar cells. In the study, Professor Yang has solved the issues associated with the thickness of the photoactive layers in OSCs, thereby taking a step closer to the realization of large-area printing process.

Photoactive layers used in solar cells convert solar energy into electrical energy. When these layers are exposed to sunlight, the excited electrons escape from the atom and generate free electrons and holes in a semiconductor. Here, the electrical energy is supplied by the movement of electrons and holes. The transfer of electrons is referred to as 'Channel I', while the movement of holes refers to as 'Channel II'.

"Fullerene-based solar cells utilize only 'Channel I due to inefficient light absorption in the thin active layers," says Sang Myeon Lee in the Combined M.S./Ph.D. program in the School of Energy and Chemical Engineering at UNIST, the first author of the study. "New solar cells are capable of utilizing both Channel I and Channel II, thereby realizing high efficiency level of 12.01%."

"This study highlights the importance of optimizing the trade-off between charge separation/transport and domain size to achieve high-performance NF-PSCs," says Professor Yang. "We will contribute to the production and commercialization of high efficiency organic solar cells in the future."

"Our study presents a new pathway for the synthesis of non-fullerene photoactive materials," says Professor Yang. "We hope to further contribute to the production and commercialization of high-efficient OSCs cell."
The findings of this study have been published in the June 22th issue of Energy & Environmental Science (EES). Published by the Royal Society of Chemistry, EES is a high-profile journal that publishes world-class energy and global environmental science research.

Journal Reference

Shanshan Chen et al., "Ultrafast Channel II process induced by a 3-D texture with enhanced acceptor order ranges for high-performance non-fullerene polymer solar cells", Energy & Environmental Science (2018).

Ulsan National Institute of Science and Technology(UNIST)

Related Solar Cells Articles from Brightsurf:

Solar cells of the future
Organic solar cells are cheaper to produce and more flexible than their counterparts made of crystalline silicon, but do not offer the same level of efficiency or stability.

A blast of gas for better solar cells
Treating silicon with carbon dioxide gas in plasma processing brings simplicity and control to a key step for making solar cells.

Record efficiency for printed solar cells
A new study reports the highest efficiency ever recorded for full roll-to-roll printed perovskite solar cells.

Next gen solar cells perform better when there's a camera around
A literal ''trick of the light'' can detect imperfections in next-gen solar cells, boosting their efficiency to match that of existing silicon-based versions, researchers have found.

On the trail of organic solar cells' efficiency
Scientists at TU Dresden and Hasselt University in Belgium investigated the physical causes that limit the efficiency of novel solar cells based on organic molecular materials.

Exciting tweaks for organic solar cells
A molecular tweak has improved organic solar cell performance, bringing us closer to cheaper, efficient, and more easily manufactured photovoltaics.

For cheaper solar cells, thinner really is better
Researchers at MIT and at the National Renewable Energy Laboratory (NREL) have outlined a pathway to slashing costs further, this time by slimming down the silicon cells themselves.

Flexible thinking on silicon solar cells
Combining silicon with a highly elastic polymer backing produces solar cells that have record-breaking stretchability and high efficiency.

Perovskite solar cells get an upgrade
Rice University materials scientists find inorganic compounds quench defects in perovskite-based solar cells and expand their tolerance of light, humidity and heat.

Can solar technology kill cancer cells?
Michigan State University scientists have revealed a new way to detect and attack cancer cells using technology traditionally reserved for solar power.

Read More: Solar Cells News and Solar Cells Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to