Computer algorithm searches for new materials for better organic solar cells

Building-Block Solar Cells

An algorithm helps find new efficient solar cell materials by reassembling already known molecular building blocks of solar cells and simulating the resulting molecules. Credit: © MPI-P

Organic carbon-based materials are already widely used in displays today, but they are also promising materials for new solar cells. However, tailoring their properties is time-consuming and requires extensive chemical synthesis and characterization. A new simulation protocol has now been developed at the Max Planck Institute for Polymer Research that combines already known molecular building blocks to form new structures and correlates them with solar cell efficiency and could thus significantly simplify development processes.

Organic solar cells could play a key role in the transition to renewable energy. However, a cheap synthetic route and high cellular efficiency help facilitate this transition. The discovery of a new class of materials, known as “non-fullerene acceptors”, offers a cost-effective synthetic route over more traditional silicon solar cells, while offering higher efficiency than early solar cells. organic.

The design of these “non-fullerene acceptor” materials with properties suitable for use in solar cells still poses challenges. A new simulation-based design methodology to simplify this procedure has now been developed in the group of Denis Andrienko, Kurt Kremer’s department at the Max Planck Institute for Polymer Research, and his colleagues. The design methodology uses already known high-efficiency organic solar cells by dividing them into several building blocks. These fragments are made up of molecular components that donate or accept electrons, called “acceptors” and “donors”. The donor and acceptor building blocks of different known solar cells can be combined to yield new “non-fullerene acceptor” molecules for use in solar cells.

“It’s a challenge to select the right one from the large number of existing molecular compounds – that’s why we use our method to access already existing solar cells and combine their molecular components to create new solar cells,” says Kun- Han Lin, a co-author of the study.

The design algorithm includes constraints that reduce the number of possible “non-fullerene acceptor” molecules, such as molecular symmetry, quadrupole moment, ionization energy, and electron affinity. For example, in cases where an acceptor-donor-acceptor combination is used, the two acceptor building blocks are always of the same type.

This design methodology is already showing promise and helping to predict the efficiency of solar cells before the materials are actually synthesized.

“We were thrilled when we realized our method was working: out of 12 planned efficient solar cells, 10 have already been produced and are very efficient,” Andrienko said.

They published their work in the famous journal Advanced Energy Materials.

Reference: “Chemical Design Rules for Non-Fullerene Acceptors in Organic Solar Cells” by Anastasia Markina, Kun-Han Lin, Wenlan Liu, Carl Poelking, Yuliar Firdaus, Diego Rosas Villalva, Jafar I. Khan, Sri HK Paleti, George T. Harrison, Julien Gorenflot, Weimin Zhang, Stefaan De Wolf, Iain McCulloch, Thomas D. Anthopoulos, Derya Baran, Frédéric Laquai and Denis Andrienko, October 8, 2021, Advanced Energy Materials.
DOI: 10.1002/aenm.202102363