New electron transport layer material could boost the stability of perovskite LEDs

A team of scientists from the NUST MISIS Laboratory of Advanced Solar Energy has proposed a new approach that uses the two-dimensional inorganic material zirconium trisulfide as the electron transport layer of a perovskite LED. In the future, this may allow the mass production of a new type of light-emitting diodes, as well as solving the problem of LED displays degradation, for example, in smartphones and TVs.

New ETL material could push forawrd perovskite LEDs image

The screens of many modern smartphones and TVs "suffer" from pixel burnout. Due to the presence of an organic component in OLED-type matrices (and their derivatives), pixels begin to degrade when the same icons on the screen are lit for a long time. So far, manufacturers advise users to periodically change the screen interface, rearrange the icons in places and regularly update the screen saver. In fact, the problem could be solved by minimizing the use of organic components in the screen matrix. Perovskite diodes are proposed as a way to make a revolution in designing screens.

Kyushu researchers use perovskites to create micrometer-thick OLEDs

Scientists at Kyushu University in Japan have created micrometer-thick organic light-emitting diodes (OLEDs) by integrating thick layers of hybrid perovskite with thin organic layers. Such devices have the potential to enhance the viewing angles and affordability of high-performance TVs and various other displays.

A test organic light-emitting diode (OLED) incorporating thick layers of hybrid perovskite emits green light imageA test organic light-emitting diode (OLED) incorporating thick layers of hybrid perovskite emits green light. (Image credit: William J. Potscavage Jr., Kyushu University)

OLEDs use layers of organic molecules to efficiently change electricity into light. While these molecules are excellent emitters, they are usually poor conductors of electricity. This is why researchers strive to use extremely thin layers (around 100 nm) to allow electricity to easily reach where emission takes place in the center of the devices.

CSoT demonstrates a 6.6" 384x300 OLED display that uses perovskite quantum dots for color conversion

China-based display maker China Star (CSoT, a subsidiary of TCL) demonstrated a 6.6-inch 384x300 OLED display that uses perovskite quantum dots as a color conversion film.

CSoT is using blue OLED emitter materials, and a perovskite layer to up-convert the color to green (this is a monochrome prototype - evidently a very early prototype). CSoT brands its perovskite-OLEDs as PE-OLED and we believe this is the first time a perovskite-enhanced display has been publicly demonstrated.

Perovskite-based quantum dots - a guest post by Ossila

What are Quantum Dots?

Quantum dots (QDs) are semiconducting nanocrystals that are very small – only a few nanometres in size. In display technologies, the most common types of QDs used are composed of a metal chalcogenide core. These QDs have the chemical formula XY – where X is a metal and Y is sulfur, tellurium or selenium (e.g. CdTe, CdSe, ZnS) – which is encased with the shell of a second semiconductor (e.g. CdSe/CdS). Their tiny dimensions mean that charge carriers are confined in close proximity, which gives QDs optical and electronic properties that are substantially different from those of large semiconductor crystals.

QLEDs vs OLEDs

In particular, QDs have enhanced light absorption and emission, making them particularly suitable for display technologies. Metal chalcogenide quantum dots (MCQDs) have already made it into commercial products – most notably, in Samsung’s QLED television range. Here, a blue LED backlight excites a layer of quantum dots on an LCD panel, causing them to emit light. The color of light emitted by the quantum dots depends on their size – with small dots emitting blue light, and progressively larger dots emitting green, yellow, orange, and red light.

Ossila QD structure imageLeft: Core-shell quantum dot structure. Right: The size of the dot defines the color of light that the dot emits. (Source: Ossila.com)