The performance of inverted quantum-dot light-emitting diodes (QLEDs) based on solution-processed hole transport layers (HTLs) has been limited by the solvent-induced damage to the quantum dot (QD) layer during the spin-coating of the HTL. The lack of compatibility between the HTL's solvent and the QD layer results in an uneven surface, which negatively impacts the overall device performance. In this work, we develop a novel method to solve this problem by modifying the QD film with 1,8-diaminooctane to improve the resistance of the QD layer for the HTL’s solvent. The uniform QD layer leads the inverted red QLED device to achieve a low turn-on voltage of 1.8 V, a high maximum luminance of 105 500 cd/m², and a remarkable maximum external quantum efficiency of 13.34%. This approach releases the considerable potential of HTL materials selection and offers a promising avenue for the development of high-performance inverted QLEDs.

Monolithic integration of III-V lasers with small footprint, good coherence, and low power consumption based on a CMOS-compatible Si substrate have been known as an efficient route towards high-density optical interconnects in the photonic integrated circuits. However, the material dissimilarities between Si and III-V materials limit the performance of monolithic microlasers. Here, under the pumping condition of a continuous-wave 632.8 nm He–Ne gas laser at room temperature, we achieved an InAs/GaAs quantum dot photonic crystal bandedge laser, which is directly grown on an on-axis Si (001) substrate, which provides a feasible route towards a low-cost and large-scale integration method for light sources on the Si platform.

Submicron-meter size GaAsBi disk resonators were fabricated with the GaAsBi/GaAs single-quantum-well (QW)-structure grown by molecular beam epitaxy. The GaAsBi/GaAs QW revealed very broad photoluminescence signals in the wavelength range of 1100–1400 nm at 300 K. The 750 nm diameter and 220 nm thick disk resonators were optically pumped and exhibited lasing characteristics with continuous wave operation at room temperature. To our knowledge, it is the first demonstration of a lasing wavelength longer than 1.3 μm with a maximum value of 1.4 μm in a GaAsBi/GaAs material system. The lasing wavelength spans about 130 nm by adjusting the disk diameter, covering almost the entire O band. The ultrasmall GaAsBi disk lasers may have great potential for highly dense on-chip integration with large tunability in the O band.