2D perovskite discovery delivers greater LED efficiency

4 June 2021

A research team led by Chair Professor Andrey Rogach (Senior Research Fellowship 2019) at City University of Hong Kong has created a new type of 2D perovskite material that improves the efficiency of perovskite nanocrystals, boosting the brightness of light-emitting diodes (LEDs) using this material.

2D perovskite is a semiconductor material developed in the past five years and described by Rogach, of the Department of Materials Science and Engineering, and colleagues as “a new class of light-harvesting and light-emitting materials” in a review published in Materials Today in 2020.

In his latest research, Rogach, in collaboration with Professor Yang Xuyong, from Shanghai University, and their teams found that the organic molecule methanesulfonate acts as a dimmer switch to improve the efficiency of perovskite nanocrystals.

When added, the molecule can reconstruct the structure of the 2D perovskite sheet and enhance exciton energy transfer between sheets of different thicknesses. It also reduces defects in the 2D perovskite structure.

LEDs that use this material can achieve a brightness of 13,400 candela/m2 at a low applied voltage of 5.5 V, and an external quantum efficiency of 20.5 per cent, close to the maximum that existing LED technologies can achieve.

In addition, it almost doubles the external quantum efficiency level of 10.5 per cent reported in the previous collaborative study by the same groups two years ago.

These findings have been published in Nature Communications.

Their work has brought perovskite LEDs much closer to current commercial display technologies, such as organic LEDs.

“The high brightness, excellent colour purity and commercial grade operating efficiency achieved mark 2D perovskites as extremely attractive materials for future commercial LEDs, and potentially display technology,” Rogach said. “It’s a tangible outcome from both fundamental and applied research into novel nano-scale materials.”

Andrey Rogach is Chair Professor of Photonics Materials in the Department of Materials Science and Engineering, City University of Hong Kong (CityU), and Founding Director of CityU’s Centre for Functional Photonics. He was awarded his PhD in Physical Chemistry from Belarusian State University in Minsk in 1995, before working as a postdoc (with Horst Weller) and then as a staff scientist at the Institute of Physical Chemistry, University of Hamburg, Germany, until 2002. This was followed by a tenured position as a lead staff scientist in the Department of Physics and Centre for NanoScience, University of Munich, Germany. In 2009, he joined CityU as a Professor, advancing to Chair Professor in 2012. He was awarded a Croucher Senior Research Fellowship in 2019.

To view Professor Rogach’s Croucher profile, please click here.