Duke team modulates the properties of organic semiconducting building blocks incorporated between layers of perovskites

Scientists at Duke University have used their electronic structure based materials modeling software on a supercomputer to help demonstrate the advantages of incorporating organic building blocks into hybrid perovskites.

The models showed that the new materials feature improved stability and safety while exhibiting a 'quantum well' behavior that can improve the performance of optoelectronic devices such as solar cells, LEDs and optical computers, making the hybrid perovskites more attractive for use in a broad range of applications.

Researchers around the world are constantly in search of new formulas for hybrid perovskites that can skirt around these limitations. In 2018, Volker Blum, associate professor of mechanical engineering and materials science and of chemistry at Duke, and colleagues at Duke and at University of North Carolina-Chapel-Hill, demonstrated accurate electronic property predictions for a series of complex, layered hybrid perovskites using high-performance computing to help in this search.

Meanwhile, researchers at Purdue University led by Letian Dou, assistant professor of chemical engineering, developed a method for incorporating long, complex organic molecules into hybrid perovskites that previously would have been extremely difficult if not impossible to include. The method adds 'side chains' to the organics to reduce the interaction between the organic molecules themselves, guiding how the organic molecules fit into the inorganic structure.

These complex organics possess semiconducting properties, allowing a thin layer sandwiched between inorganic layers to exhibit quantum well properties. These types of materials might be used to create compact, fast computer chips, highly efficient microscopic lasers and optoelectronic devices.

'These structures are very exciting,' said Dou of the new hybrid perovskites. 'The sandwich structures are like those that are widely used today in many electronic and optoelectronic devices, but they are much easier to produce and more tolerant to defects.'

While the engineers at Purdue could engineer these new hybrid perovskites, they wanted to make sure they understood the electronic structure of the materials and that they would exhibit the desired quantum well behaviors. They turned to Blum and his supercomputer models to validate their expectations. The resulting models aligned well with the expectations and experimental results.

'These structures are conceptually similar to those for which we first demonstrated our approach in 2018, but realize the promise of extending it to a broader scope of organic molecules with desirable properties,' said Blum. 'These are precisely the sorts of materials we were hoping our models would help advance.'

In further research, the Purdue team has already shown that these new hybrid perovskites can be made free of lead while exhibiting increased stability and performance in a field effect transistor (FET), an electronic device that uses an electric field to control the flow of current. FETs are used in integrated circuits in devices such as computers and wireless communications.

The potential uses for this type of material are broad because semiconductors are the foundation of essentially all electronic and optoelectronic devices like transistors, solar cells, LEDs, and photodetectors. The new organic-inorganic hybrid perovskite materials are cheaper and perform better than a traditional inorganic semiconductor. And the new materials design strategy could serve as a blueprint for many other functional hybrid materials.

'With our new technology, we can make the hybrid perovskite materials intrinsically more stable,' noted Yao Gao, a postdoctoral fellow in Dou's research group. 'By replacing the toxic lead, these new materials are better for the environment, and can also be safely used for bioelectronics sensors on the body.'

Posted: Nov 21,2019 by Roni Peleg