Organic-inorganic hybrid perovskites (OIHPs) have great potential for various applications like solar cells, lighting-emitting diodes (LEDs), field effect transistors (FETs) and photodetectors. Among their most important parameters influencing the power conversion efficiency (PCE) of devices based on perovskite materials is their carrier mobility. However, despite massive progress made by introducing new components into the structure to control the mobility of the carriers, the understanding on the atom level of how the components affect the performance is still lacking.

To address this problem, a research team led by Prof. Luo Yi and Prof. Ye Shuji from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) has synthesized a series of 2D OHIPs films with large organic spacer cations.

Researchers from Pohang University of Science and Technology in Korea have received Universal Display Corporation's 2020 Innovative Research and Pioneering Technology Award in Organic Electronics & Display, for their work 'High-Performance and Reliable Lead-Free Layered-Perovskite Transistors'. Universal Display (UDC) is a large OLED research company, considered to be a pioneer in field.

In their work, the scientists explain that despite extensive examination of perovskites' potential use in solar cells and light'emitting diodes, research on their applications in thin'film transistors (TFTs) has drawn less attention despite their high intrinsic charge carrier mobility. In this study, the universal approaches for high'performance and reliable p'channel lead'free phenethylammonium tin iodide TFTs are reported.

A Purdue University-led research team discovered that adding a rigid bulky molecule ' bithiophenylethylammonium ' to the surface of a perovskite stabilizes the movement of ions, preventing chemical bonds from breaking easily. The researchers also demonstrated that adding this molecule makes a perovskite stable enough to form clean atomic junctions with other perovskites, allowing them to stack and integrate.

'If an engineer wanted to combine the best parts about perovskite A with the best parts about perovskite B, that typically can't happen because the perovskites would just mix together,' said Brett Savoie, a Purdue assistant professor of chemical engineering. 'In this case, you really can get the best of A and B in a single material. That is completely unheard of.'

University of California, Berkeley, scientists have created a blue light-emitting diode (LED) from halide perovskites, overcoming a major barrier to using these cheap, easy-to-make materials in electronic devices.

In the process, however, the researchers discovered a fundamental property of halide perovskites that may prove a barrier to their widespread use as solar cells and transistors. Alternatively, this unique property may open up a whole new world for perovskites far beyond that of today's standard semiconductors.

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 at KU Leuven have explained how a promising type of perovskites can be stabilized. The team has developed a process in which the crystals turn black, enabling them to absorb sunlight. This is said to be necessary in order to use them in solar panels.

"Silicon forms a very strong, rigid crystal. If you press on it, it won't change its shape. On the other hand, perovskites are much softer and more malleable," explains Dr. Julian Steele of the KU Leuven Centre for Membrane Separations, Adsorption, Catalysis, and Spectroscopy for Sustainable Solutions (cMACS). "We can stabilize them under various lab conditions, but at room temperature, the black perovskite atoms really want to reshuffle, change structure, and ultimately turn the crystal yellow".

Researchers from Rutgers University, University of Minnesota and University of Texas at Dallas in the U.S have discovered a new type of electric field effect that can control light emission from perovskite devices.

The electric field effect usually refers to the modulation of electrical conductivity in a semiconductor by means of an applied voltage to a gate electrode and forms the basis of modern digital electronics. In a conventional field effect transistor (FET), the conductivity of a semiconductor layer can be turned on or off or gradually ramped up or down. Now, the research team has found that the photoluminescence (PL) of a perovskite device can be modulated in a similar manner. 'Our work reports a novel type of field effect in which PL, rather than conductivity, is tuned by an 'electric knob' ' the gate voltage,' explains Vitaly Podzorov, who led the research.

An international team of researchers, led by Aram Amassian at North Carolina State University, has demonstrated the construction of field-effect transistors using a single crystal, hybrid perovskite semiconductor.

While the design of perovskite solar cells has matured to the point of near-commercialization, making hybrid perovskites function as field-effect transistors has been more of a challenge. This is in part due to the fact that perovskite films typically consist of multiple crystals with random orientations that include grain boundaries and various kinds of defects in their atomic crystal lattices. These often limit how well charge carriers (electrons or 'holes') can move through them.

An international team of researchers, including ones from KAUST, the Guo China-US Photonics Laboratory, the University of Rochester and the University of New South Wales, has developed a technique that allows single-crystal hybrid perovskite materials to be integrated into electronics. The team stated that this achievement opens the door to new research into flexible electronics and potentially reduced manufacturing costs for electronic devices.

Challenges in integrating single-crystal hybrid perovskites into electronic devices, such as transistors, have spurred much research focus. The main challenge in incorporating single-crystal hybrid perovskites into electronics stems from the fact that these macroscopic crystals, when synthesized using conventional techniques, have rough, irregular edges. This makes it difficult to integrate with other materials in such a way that the materials make the high-quality contacts necessary in electronic devices.

A research team composed of scientists from Michigan State University and University of Michigan has deployed a new approach to growing all inorganic lead-free halide perovskites.

"Epitaxial growth has long since revolutionized the study of many electronic materials including silicon, oxide perovskites, and III-V semiconductors," said Richard Lunt, an Associate Professor at Department of Chemical Engineering and Materials Science, Michigan State University who has supervised the project. "There is very little known about the epitaxial growth of halide perovskites, but these exciting materials hold enormous potential. This has motivated us to explore this entirely new research area."