Perovskite/quantum dot interation improves LED and solar performance

February 10, 2016 // By Paul Buckley
Researchers in Valencia have studied the interaction of two materials, halide perovskite and quantum dots, revealing the potential for the development of advanced LEDs and more efficient solar cells.

Researchers from the Universitat Jaume I (James I University, UJI) and the Universitat de València (University of Valencia, UV) have quantified the 'exciplex state' resulting from the coupling of halide perovskites and colloidal quantum dots. Both known separately for their optoelectronic properties, when brought together these materials yield much longer wavelengths than can be achieved by either material alone, plus easy tuning properties that together have the potential to usher in important changes in LED and solar technologies.

Perovskite materials are cheap to produce, simple to manufacture and efficient.  The materials can be used in solar cells and are also used in LED technology. Quantum dots (QDs), for their part, are a family of semiconductor materials with light-emitting properties, including the ability to tune what wavelengths light is emitted. Quantum dots can also be useful in both LEDs and solar cells.

The result of bringing the two materials together is a 'exciplex state' where light can be emitted at much longer wavelengths, reaching well into the infrared spectrum, while also allowing control over its emission colour via applied voltage. Each material - the perovskite, the QDs and the new exciplex state - emits light at a different colour, each of which can be weighted within the overall light emission to pick out the desired colour.

The materials aanle LEDs to be designed which can emit light over both the visible and infrared spectrums at the same time, which would have applications in the field of telecommunications.

Working on the basis of the reciprocity principle, the 'exciplex state' will potentially lead to the development of solar cells that can transform more of the sun’s light into electrical energy. Currently solar cells can only transform light emitted over a relatively narrow band of wavelengths. But if it is possible to produce light at longer wavelengths via an electrical input, then it is theoretically possible to obtain electrical energy by absorbing light with these longer wavelengths, thereby increasing the efficiency of solar cells.