Search

The efficiency and stability issues of perovskite light-emitting diodes, especially at high brightness, need to be urgently solved for displays and lighting applications. Herein we present a simple chemical washing method called solvent sieve to resolve the phase dimension issue of metal halide perovskites. After being sieved, undesirable defect-rich low-nphases are selectively screened out of perovskite multi-quantum-well structures. With better intrinsic structure refinement, the sieved perovskites demonstrated not only a record external quantum efficiency, current efficiency, and T50lifetime of 29.5%, 127.4 cd A−1, and 18.67 h at 12,000 cd m−2(the equivalent of over 50,317 h or 5.7 years at 100 cd m−2), respectively, with a maximum luminance of over 147,872.8 cd m−2, but also extraordinary resistance to air and moisture, maintaining over 75% of film photoluminescence quantum yield and 80% of device EQE after being stored at ambience for 100 days. The simple solvent sieve treatment we reported here confirms the feasibility of metal halide perovskites for luminescence and unleashes the efficiency and stability potentials of high-brightness perovskite light-emitting diodes for future commercial applications.

Inverted perovskite light-emitting diodes (PeLEDs) based on quantum dots (QDs) are some of the most promising candidates for next-generation lighting and display applications. Due to the strong fluorescence quenching caused by zinc oxide, high performance in such inverted devices remains challenging. Here, we report an efficient inverted green CsPbBr3QDs LED using an emitting buffer layer. Ultrathin CsPbBr3QD emitters act as the buffer layer to reduce the interface luminescence quenching reaction at the ZnO/upper emitting layer interface, increasing the probability of exciton recombination within the emissive layer and regulating the charge transport, leading to effective carrier recombination. The resulting device exhibits an external quantum efficiency of 13.1%, enhanced by about 4.7 times compared with that without a buffer layer device. This work provides a path to fabricating high-performance inverted PeLEDs.

The interface VOCloss between the active layer and the hole transport layer (HTL) of lead sulfide colloidal quantum dot (PbS-CQD) solar cells is a significant factor influencing the efficiency improvement of PbS colloidal quantum dot solar cells (PbS-CQDSCs). Currently, the most advanced solar cells adopt organic P-type HTLs (PbS-EDT) via solid-state ligand exchange with 1,2-ethanedithiol (EDT) on the CQD top active layer. However, EDT is unable to altogether remove the initial ligand oleic acid from the quantum dot surface, and its high reactivity leads to cracks in the HTL film caused by volume contractions, which inevitably results in significant VOCloss. These flaws prompted this research to develop a method involving hybrid organic ligand exchange using 3-mercaptopropionic acid (MPA) and 1,2-EDT (PbS-Hybrid) to overcome these drawbacks of VOCloss. The results indicated that the new exchange strategy improved the quality of the HTL film and benefited from the enhanced passivation of the quantum dot surface and better alignment of energy levels, and the average VOCof PbS-Hybrid devices is increased by approximately 25 mV compared to control devices. With the enhanced VOC, the average power conversion efficiency (PCE) of the devices is improved by 10%, with the highest PCE reaching 13.24%.

Perovskite quantum dot light-emitting diodes (QLEDs) are potential candidates for next-generation displays due to their high color purity and wide color gamut. Due to the strong electron-accepting ability of poly[bis(4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA), quantum dot (QD) films are prone to be charged, which leads to the imbalance of charge injection and the increase of nonradiative recombination, ultimately affecting the performance of the QLEDs. Here, we compared and studied two polymers, poly(methyl methacrylate) (PMMA) and poly(vinyl pyrrolidone) (PVP), as the hole interface buffer layers of QD films, which effectively reduced the defect density, suppressed nonradiative recombination, and greatly improved the efficiency and stability of QLEDs. The devices with PMMA achieved a maximum external quantum efficiency of 20.71%.

A new proton-promoted in situ ligand exchange strategy based on CsPbI3quantum dots.The ligand exchange strategy maintains the quantum confinement effect of quantum dots and significantly improves the stability and photophysical properties of CsPbI3quantum dots.The performance of light-emitting diodes based on CsPbI3quantum dots is significantly improved, the external quantum efficiency is increased from 18.63% to 24.45%, and the half-operational lifetime is increased by 70 times.

Rapid improvements in the operating lifetimes of QLEDs, as well as investments into large-scale production lines for inkjet printing, are bringing the electroluminescent application of quantum dots for flat-panel displays closer to commercialization.

A solution-processed molybdenum oxide (MoOx) as the hole injection layer (HIL) by doctor-blade coating was developed to improve the efficiency and lifetime of red-emitting quantum-dot light-emitting diodes (QD-LEDs). It has been demonstrated that by adding isopropyl alcohol into the MoOxprecursor during the doctor-blade coating process, the morphology, composition, and the surface electronic structure of the MoOxHIL could be tailored. A high-quality MoOxfilm with optimized charge injection was obtained, based on which all-solution-processed highly efficient red-emitting QD-LEDs were realized by using a low-cost doctor-blade coating technique under ambient conditions. The red QD-LEDs exhibited the maximum current efficiency and external quantum efficiency of 16 cd/A and 15.1%, respectively. Moreover, the lifetime of red devices initializing at 100 cd/m2was 3236 h under ambient conditions, which is about twice as long as those with a conventional poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) HIL. Large-area QD-LEDs with 4 in. emitting areas were fabricated with blade coating as well, which exhibit a high efficiency of 12.1 cd/A for red emissions. Our work paves a new way to the realization of efficient large-area QD-LEDs, and the processing and findings from this work can be expanded into next-generation lighting and flat-panel displays.

Recent progress has been reported regarding high color gamut blue QDs development, improvement of QLEDs performance including efficiency and lifetime, and development of printable QD inks and ink-jet printing technique of QLEDs, in order to solve those key challenges towards QLED display technology commercialization.

Guangdong Juhua has fabricated the world’s first 31 inch, 4K, H‐QLED TV, by using ink‐jet printing technology. The Red and Green pixel of H‐QLED TV is made from electrical luminescence quantum dot (QD for short) materials, and Blue pixel is made from soluble blue OLED material. It is a self‐emitting and top emission display with excellent performance brought by quantum dot materials, which provide large colour gamut, wider view angle, high luminance and high resolution.