November 2019

Researchers at the Georgia Institute of Technology have demonstrated a novel approach aimed at addressing perovskite's durability problem: encasing the perovskite inside a double-layer protection system made from plastic and silica.

The research team developed a multi-step process to produce encased perovskite nanocrystals that exhibit strong resistance to degradation in moist environments.

Researchers at the Massachusetts Institute of Technology (MIT) have improved a transparent and conductive coating material by increasing its electrical conductivity by 10 times. When this coating material was integrated into a perovskite solar cell, it boosted the stability and efficiency of the solar cell.

'The goal is to find a material that is electrically conductive as well as transparent,' explained the team, which would be ‘'useful in a range of applications, including touch screens and solar cells.'

Researchers at Japan's OIST, in collaboration with the University of Pittsburgh in the U.S., have characterized the structural defects that prompt the movement of ions, destabilizing perovskite materials. The researchers' findings may help optimize perovskite solar cells.

This image of a perovskite surface shows the shifting of ions across the surface, and the vacancies causing these movements. Image by OIST

"For a long time, scientists have known structural defects exist, but didn't understand their precise chemical nature," said Collin Stecker, an OIST Ph.D. student and the first author of the study. "Our study delves into fundamental characteristics of perovskite materials to help device engineers further improve them."

An international research team that included scientists from the University of Exeter, in the U.K., Switzerland's Ecole Polytechnique Federale de Lausanne (EPFL) and Saudi Arabia's Center of Excellence for Advanced Materials Research has reported hitting 21.6% perovskite solar cell efficiency by using concentrator photovoltaic technology.

PSC with a concentrator

A triple-cation based, n-i-p structured perovskite cell has reportedly been developed at low levels of solar concentration. According to the researchers, standard single-junction perovskite cells usually reach efficiencies of 21% but only in devices smaller than 1mm². 'The use of concentrator photovoltaics with a 0.81mm²-sized perovskite solar cell (PSC) further increased the efficiency levels up to 23.1% opening up a new line of research combining PSCs with low concentrating photovoltaic technologies,' the authors of the study wrote.

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.

Scientists from Nanyang Technological University and Singapore's NTU, in collaboration with the University of Groningen (UG) in the Netherlands, have developed a method to analyze which pairs of materials in perovskite solar cells will harvest the most energy.

In their recent study, physicists Professor Sum Tze Chien from NTU and Professor Maxim Pshenichnikov from UG used extremely fast lasers to observe how an energy barrier forms when perovskite is joined with a material that extracts the electrical charges to make a solar cell.

A research group led by Prof. Liu Shengzhong from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) and Prof. Yang Dong at Shaanxi Normal University have developed high efficiency semi-transparent perovskite solar cells by using MoO₃ sandwiched gold nanomesh (MoO₃/Au/MoO₃) multilayer as the transparent electrode. Combined with a superior heterojunction silicon solar cell, a high efficiency four-terminal perovskite/silicon tandem solar cell was obtained.

Tandem/multijunction structure has been proven to be an effective way to break the Shockley-Queisser limit. To obtain a high efficiency tandem solar cell, the key is to fabricate transparent electrode with high conductivity as well as high transparency through a mild method.

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

Stabilizing perovskite solar cells would solve a key issue that s currently delaying commercialization of PSCs 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.

Researchers from Helmholtz-Zentrum Berlin (HZB), headed by Prof. Susan Schorr and Dr. Joachim Breternitz, have achieved a breakthrough in understanding the crystalline structure of hybrid halide perovskites. The team investigated crystalline samples of methylammonium lead iodide (MAPbI₃), the most prominent representative of this class of materials, at the Diamond Light Source synchrotron (DLS) in the United Kingdom using high-resolution single-crystal diffraction. This approach provided data for a more in-depth analysis of the crystalline structure of this material.

They were also able to clarify, whether ferroelectric effects are possible at all in this hybrid halide perovskite. Ferroelectric domains can have favorable effects in solar cells and increase their efficiency. However, measuring this effect in samples is difficult - a null result can mean that there is either no ferroelectric effect or that the ferroelectric domains cancel one another's effects out.

Scientists at the University of Cambridge studying perovskite materials for use in solar cells and flexible LEDs have discovered that they can be more efficient when their chemical compositions are less ordered, simplifying production processes and lowering cost.

The surprising findings are the result of a collaborative project, led by Dr. Felix Deschler and Dr. Sam Stranks.