Researchers use a micro-LED covered with perovskite QDs to achieve high-speed visible light communication

Researchers from Fudan University in China have developed a high-bandwidth white-light based system made from a blue gallium nitride (GaN) micro-LED with yellow-emitting perovskite quantum dots. This system could open the door to high-speed real-time visible light communication (VLC).

The researchers used a 80 x 80 um blue-emitting micro-LED that has a modulation bandwidth of about 160 MHz and a peak emission wavelength of ~445 nm. The white-light system (following the perovskite QD conversion) achieves 85 Mhz - which means a maximum data rate of 300 Mbps.

Emberion team design perovskite-QDs that combine with graphene to create unique photodetectors

Emberion researchers have shown that colloidal quantum dots (QDs) combined with a graphene charge transducer can provide a photoconducting platform with high quantum efficiency and large intrinsic gain, yet compatible with cost-efficient polymer substrates. The team demonstrated methods to couple large QDs (>6 nm in diameter) with organometal halide perovskites, enabling hybrid graphene photo-transistor arrays on plastic foils.

Emberion team uses graphene and perovskite QDs for advanced photodetctors

The resulting arrays simultaneously exhibited a specific detectivity of 5 × 1012 Jones and high video-frame-rate performance. PbI2 and CH3NH3I co-mediated ligand exchange in PbS QDs improved surface passivation and facilitated electronic transport, yielding faster charge recovery, whereas PbS QDs embedded into a CH3NH3PbI3 matrix produce spatially separated photocarriers leading to large gain.

New perovskite-quantum dots hybrid may enable efficient and affordable solar cells

Researchers at the National Renewable Energy Laboratory (NREL) and the University of Washington have designed an interesting strategy for driving down the cost of solar cells while ramping up efficiency: the team developed a high cost, high efficiency quantum dot solar cell for space applications, and provided the expensive solar cell up with a cheaper perovskite layer. The combined solar cell would be aimed at terrestrial applications with a more moderate price point. Note that in the proposed lower cost solar cell, the cheap layer is not the only role for perovskite. The expensive quantum dot layer would also be made of perovskite.

The NREL team explains that colloidal quantum dots are electronic materials and because of their astonishingly small size (typically 3-20 nanometers in dimension) they possess fascinating optical properties. That first quantum dot solar cell had a conversion efficiency of just 2.9% and was based on a lead sulfide formula. Things moved along quickly after that, and NREL noted a record of 12% for lead sulfide achieved by the University of Toronto just last year.

Fuji Pigment announced development of Perovskite quantum dots

Fuji Pigment recently reported that it is researching and developing a new type of perovskite quantum dots. Fuji stated that the half width of their emission spectra is substantially narrower than that of InP; this property could very beneficial to the application of the dots in display materials, LED, bio-imaging and more.

Fuji's perovskite QDs emission spectra imageemission spectra of perovskite quantum dots under 420 nm of irradiation light

The chemical composition of perovskite quantum dots are either CsPbX3 or CH3NH3PbX3 (X= Cl, Br, I). Their quantum efficiency is 50–80 % and their half width is 15–39 nm. Their base solvent is either hexane or toluene. However, finding alternative solvents is a challenge that is now being addressed.

EPFL team develops new method to stabilize perovskite quantum dots

EPFL researchers have designed a new type of inorganic nanocomposite that makes perovskite quantum dots (nanometer-sized semiconducting materials with unique optical properties) exceptionally stable against exposure to air, sunlight, heat, and water.

EPFL team stabilizes perovskite QDs image

Quantum dots made from perovskites have already been shown to hold potential for solar panels, LEDs and laser technologies. However, perovskite quantum dots have major issues with stability when exposed to air, heat, light, and water. The EPFL team has now succeeded in building perovskite quantum dot films with a technique that helps them overcome these weaknesses.