G.T. Du

High-Efficiency and Air-Stable Perovskite Quantum Dots Light-Emitting Diodes with an All-Inorganic Heterostructure

Perovskite light-emitting diodes (PeLEDs), because of its fundamental scientific importance and practical applications in the fields of low-cost light source or display applications, have drawn worldwide attention in recent years. However, PeLEDs available today suffer from a compromise in their emission efficiency and operation stability. In this study, we designed and fabricated a stacking all-inorganic multilayer structure by using inorganic perovskite CsPbBr3 quantum dots (QDs) as the emissive layer and inorganic n-type MgZnO and p-type MgNiO as the carrier injectors, respectively. Through energy band engineering of carrier injectors by Mg incorporation and their thickness optimization, PeLEDs with maximum luminance of 3809 cd/m2, luminous efficiency of 2.25 cd/A, and external quantum efficiency of 2.39% have been realized, which are much better than most PeLEDs from CH3NH3PbBr3 films, and comparable with the highest results reported on CsPbBr3 QDs LEDs. More importantly, the unencapsulated PeLEDs in a continuous current mode demonstrate a remarkable operation stability against water and oxygen degradation. After a continuous operation for 10 h under a dc bias (10.0 V), nearly 80% of the original efficiency of the PeLEDs has been retained, greatly superior to reference and other previously reported devices constructed with conventional organic carrier injectors. Our results obtained open possibilities for the design and development of high-efficiency and air-stable PeLEDs that are not dependent on expensive and less-stable organic carrier injectors.

Electroluminescence from n-ZnO/p-ZnO : Sb homojunction light emitting diode on sapphire substrate with metal–organic precursors doped p-type ZnO layer grown by MOCVD technology

An n-ZnO/p-ZnO : Sb homojunction light emitting diode was fabricated on c-plane sapphire by metal–organic chemical vapour deposition (MOCVD). The p-type ZnO layer with a hole concentration of 1.27 × 1017 cm−3 was fabricated using trimethylantimony (TMSb) as the Sb doping source. The current–voltage characteristics of the device exhibited a desirable rectifying behaviour with a turn-on voltage of 3.3 V. Distinct electroluminescence with ultraviolet and visible emissions was detected from this device under forward bias at room temperature. Moreover, metal–organic source TMSb is an effective and controllable dopant in the MOCVD technique, which is suitable for further industrialized production.

p-Type Sb-Doped ZnO Thin Films Prepared by Metallorganic Chemical Vapor Deposition Using Metallorganic Dopant

Reproducible p-type Sb-doped ZnO thin films were fabricated on c-plane sapphire substrates by the metallorganic chemical vapor deposition (MOCVD) technique using trimethylantimony as the doping precursor. Sb was introduced into ZnO thin films as a p-type dopant without any phase separation. Obvious donor-acceptor pair emissions were observed from photoluminescence spectra of ZnO:Sb films at 10 K. The acceptor binding energy is estimated to be ∼ 124 meV. Using the metallorganic source as the dopant of p-type ZnO thin films by the MOCVD technique is beneficial for the industrialized production of ZnO light-emitting diodes.

ZnO-based homojunction light-emitting diodes fabricated by metal-organic chemical vapor deposition

ZnO p–n homojunction light-emitting diodes were fabricated on p-GaAs substrates by metal-organic chemical vapor deposition. The current–voltage characteristics showed a diode characteristic between the n-type and p-type ZnO layers with a threshold voltage of 3.8 V. We present a room-temperature study of photoluminescence (PL) spectra and electroluminescence (EL) spectra. The PL spectra of both n-type and p-type ZnO exhibited strong near-band-edge emission and weak broad deep-level emission peaks. The EL spectra showed a strong broad deep-level emission when the injection current attained 40 mA, and a weak ultraviolet emission emerged when the current attained 150 mA.

Study on the properties of MgxZn1?xO-based homojunction light-emitting diodes fabricated by MOCVD

A MgxZn1−xO p–n homojunction light-emitting diode (LED) was fabricated on the GaAs substrate by metal–organic chemical vapour deposition (MOCVD). The I–V curve of the device exhibited typical rectifying behaviour of the p–n diode. The forward turn-on voltage was about 3.5 V. The photoluminescence spectra of the n-type and p-type MgxZn1−xO layers exhibited obvious near-band-edge emission peaks and weak deep-level emission peaks. In the electroluminescence (EL) spectra of the diode, a broad emission band from 2.3 to 2.8 eV can be observed. The emission band near 3.31 eV did not appear until the injection current reached 180 mA. The differences in the EL spectra between ZnO and MgxZn1−xO LEDs are also discussed.

Effects of Si-doping on field emission characteristics of AlN films grown on n-type 6H-SiC by MOCVD

Abstract The field-emission (FE) characteristics of 200 nm-thick Si-doped AlN films with different concentration of Si-dopant is investigated. It is found that the AlN film with lower concentration of Si-dopant has a smaller turn-on voltage, larger maximum current density and more stable FE current. Accompanying with atomic force surface micro-images, it is suggested that the stable current is attributed to a uniform surface, which is related a uniform local field enhancement factors and thus a stable FE current without discontinuous fluctuations. Furthermore, the analysis of scanning electron microscopy indicates that a smaller turn-on voltage and larger maximum current density may result from the electron transport channel of V-defects.