Organic dopants for a stable perovskite

• Researchers at Saudi Arabia’s King Abdullah University of Science and Technology have demonstrated a method they say could improve the stability of perovskite structures. The group found adding an organic dopant served to increase the strength of chemical bonds between organic and inorganic elements of a perovskite.

Adding certain organic materials – those with particles “of the right shape and volume” – could help to increase the stability of perovskite solar cells, according to a study published by scientists at King Abdullah University of Science and Technology (KAUST).

Stabilizing perovskite solar cells would solve a key issue preventing commercialization of the promising technology and could provide a more comprehensive solution than other approaches which center on managing perovksite’s inherent instability in the atmosphere by encapsulating them. Another recent study, from Rice University in the United States, found adding indium in an all-inorganic perovskite limited defects and improved stability.

Using computational modelling, the KAUST group took a different approach to much of the research on stabilizing perovskites by examining the role of hydrogen and halogen bonding in the material, rather than focusing on stronger covalent bonding.

In the mix

The modelling of the KAUST group, described in a paper in Advanced Energy Materials, demonstrated adding organic dopants to the mix in a lead halide formamidinium (FA) perovskite served to increase stability of the structure. With the dopants, the FA could bond more strongly to the inorganic ‘skeleton’ of the material.

The group found compounds with covalent and non covalent bonded chlorine atoms or ions could be especially effective at helping suppress “X-migrations” – damaging movements in the halide materials. According to Udo Schwingenschlögl, professor in applied physics at KAUST, the discovery could improve the performance of perovskite solar cells as well as their stability.

“Our motivation was to apply new computational methods to one of the hottest problems in the field of perovskite solar cells,” said KAUST Ph.D student Aleksandra Oranskaia, the paper’s lead author. “We show that doping with organic cations of the right volume and shape – those that bond more strongly than FA [formamidinium] to the inorganic skeleton via hydrogen and halogen bonding – can stabilize the material.”

The group will now look to expand its study on the effects of non-covalent bonding on stability to a broader range of solar cell materials.