Nanosurface-reconstructed perovskite for highly efficient and stable active-matrix light-emitting diode display.

Perovskite quantum dots (QDs) are promising for various photonic applications due to their high colour purity, tunable optoelectronic properties and excellent solution processability. Surface features impact their optoelectronic properties, and surface defects remain a major obstacle to progress. Here we develop a strategy utilizing diisooctylphosphinic acid-mediated synthesis combined with hydriodic acid-etching-driven nanosurface reconstruction to stabilize CsPbI3 QDs. Diisooctylphosphinic acid strongly adsorbs to the QDs and increases the formation energy of halide vacancies, enabling nanosurface reconstruction. The QD film with nanosurface reconstruction shows enhanced phase stability, improved photoluminescence endurance under thermal stress and electric field conditions, and a higher activation energy for ion migration. Consequently, we demonstrate perovskite light-emitting diodes (LEDs) that feature an electroluminescence peak at 644 nm. These LEDs achieve an external quantum efficiency of 28.5% and an operational half-lifetime surpassing 30 h at an initial luminance of 100 cd m-2, marking a tenfold improvement over previously published studies. The integration of these high-performance LEDs with specifically designed thin-film transistor circuits enables the demonstration of solution-processed active-matrix perovskite displays that show a peak external quantum efficiency of 23.6% at a display brightness of 300 cd m-2. This work showcases nanosurface reconstruction as a pivotal pathway towards high-performance QD-based optoelectronic devices.

Controlling Interfacial Amidation Reaction Rate to Regulate Crystal Growth toward High-Performance FAPbBr3-Based Inverted Light-Emitting Diodes.

Controlling interfacial reactions is critical for zinc oxide (ZnO)-based inverted perovskite light-emitting diodes (PeLEDs), boosting the external quantum efficiency (EQE) of the near-infrared device to above 20%. However, violent interfacial reactions between the bromine-based perovskites and ZnO-based films severely limit the performance of inverted green PeLEDs, whose efficiency and stability lag far behind those of their near-infrared counterparts. Here, a controllable interfacial amidation between the bromine-based perovskites and magnesium-doped ZnO (ZnMgO) film utilizing caprylyl sulfobetaine (SFB) is realized. The SFB molecules strongly interact with formamidinium bromide, decelerating the amidation reaction between formamidinium and carboxylate groups on the ZnMgO film, thus regulating the crystallization of FAPbBr3. Combined with the passivation of benzylamine, a FAPbBr3 bulk film directly deposited on a ZnMgO substrate with single-crystal characteristics is obtained, exhibiting a high photoluminescence quantum yield of above 80%. The resultant PeLEDs demonstrate a peak EQE of exceeding 20% at a high luminance of 120,000 cd m-2 and a half lifetime of 26 min at 11,000 cd m-2, representing the state-of-the-art inverted green electroluminescence. This work resolves the crucial issues of violent interfacial reactions and provides a strategy toward inverted green PeLEDs with outstanding performance.

Efficient and bright broadband electroluminescence based on environment-friendly metal halide nanoclusters.

Broadband electroluminescence based on environment-friendly emitters is promising for healthy lighting yet remains an unprecedented challenge to progress. The copper halide-based emitters are competitive candidates for broadband emission, but their high-performance electroluminescence shows inadequate broad emission bandwidth of less than 90 nm. Here, we demonstrate efficient ultra-broadband electroluminescence from a copper halide (CuI) nanocluster single emitter prepared by a one-step solution synthesis-deposition process, through dedicated design of ligands and subtle selection of solvents. The CuI nanocluster exhibits high rigidity in the excitation state as well as dual-emissive modes of phosphorescence and temperature-activated delayed fluorescence, enabling the uniform cluster-composed film to show excellent stability and high photoluminescent efficiency. In consequence, ultra-broadband light-emitting diodes (LEDs) present nearly identical performance in an inert or air atmosphere without encapsulation and outstanding high-temperature operation performance, reaching an emission full width at half maximum (FWHM) of ~120 nm, a peak external quantum efficiency of 13%, a record maximum luminance of ~50,000 cd m-2, and an operating half-lifetime of 137 h at 100 cd m-2. The results highlight the potential of copper halide nanoclusters for next-generation healthy lighting.

Novel 2D hybrids composed of SnIn4S8 nanoplates on BiOBr nanosheets for enhanced photocatalytic applications.

In the last ten years, bismuth oxybromide (BiOBr) has attracted wide attention due to its superior optoelectronic property. However, its practical application still suffers from slow carrier transport and high carrier recombination. Here we report a kind of novel tannum indium sulfide (SnIn4S8)/BiOBr hybrid prepared by a two-step hydrothermal method. The results showed that small amount of SnIn4S8 had no influence on the crystal phase of BiOBr, but the morphology could be regulated from nanosheet to nanoflower. Specially, SnIn4S8 exerted a slight effect on the light absorption and band gap of BiOBr. Importantly, SnIn4S8/BiOBr hybrids exhibited remarkable enhancement of the photocatalytic activity towards the degradation of rhodamin B (RhB) dye molecules. SnIn4S8/BiOBr-0.20 with 99.8% degradation efficiency had the highest photocatalytic activity within 40 min, while it was only 71.1% for pure BiOBr. The enhanced photocatalytic activity was mainly attributed to efficient interfacial transfer and low carrier recombination. This work will help us understand the photocatalytic mechanism of bismuth oxyhalide hybrids.