Nanorods (NRs) hold promise for surpassing the theoretical external quantum efficiency limit of light-emitting diodes (LEDs) based on spherical quantum dots (QDs) due to their linearly polarized emission and high photon out-coupling efficiency. Compared with the most studied dot-in-rod NRs, rod-in-rod NRs have higher degree of polarization. However, due to the difficulties in achieving uniform NR seeds, synthesizing rod-in-rod NRs that cover the entire visible spectrum remains a significant challenge, especially for green and blue ones. In this study, high-quality and uniformly sized green CdSeS NRs were successfully synthesized by systematically optimizing the S/Se ratio, the nucleation temperature and the amount of ligand. Based on these high-quality NR seeds, CdSeS/CdZnS/ZnS core-shell NRs were further prepared with narrow emission bandwidths (28 nm at 540 nm), high photoluminescent quantum yield (75%) and high linear polarization (r = 0.3). This study provides a new possibility for the application of NRs in LEDs, lasers and other optoelectronic devices.

InP quantum dots (QDs) are promising heavy-metal-free materials for next-generation solid-state lighting, covering from visible to near-infrared (NIR) range. Compared with the rapid development of visible InP QDs, the synthesis of high-performance NIR InP QDs remains to be solved. In this work, we report a simple one-pot synthesis of NIR InP QDs by controlling the Cu doping and designing a multishell structure. By replacing the conventional highly reactive phosphorus precursor with a slightly less reactive and low-cost ammonia phosphorus precursor, the nucleation process is effectively regulated for efficient Cu doping. In addition, the epitaxial growth of the ZnSe/ZnS shell further improves the stability and optical properties of InP QDs. Therefore, the synthesized Cu:InP/ZnSe/ZnS QDs have a photoluminescence quantum yield of 70% centered at 833 nm. The NIR InP light-emitting diodes exhibit a maximum radiance of 3.1 W·sr⁻¹·m⁻² and a peak external quantum efficiency of 2.71% centered at 864 nm.

Inorganic halide perovskites such as cesium lead iodide (CsPbI₃) have drawn tremendous attention, as their tunable band gaps are desirable for solar cells as well as light emitting diodes. However, due to their low Goldschmidt tolerance factor, the cubic phase of bulk CsPbX₃—the variant with desirable band gap—is not stable in ambient, especially in humid air. Besides, the low solubility of CsX in precursor makes it difficult to control the film thickness and morphology of CsPbX₃, which becomes another obstacle for the practical application of inorganic perovskite. Here, we report a polymer assisted deposition of high-quality CsPbI₂Br film by spin-coating a polymer-blended CsPbI₂Br precursor. The long-chained polymer increases the viscosity of the solution, which enables us to achieve a ca. 700-nm thick film with a low solution concentration of CsPbI₂Br. Moreover, the polymer network helps to regulate the crystallization process and provides more crystallization sites for perovskite film, reducing grain size and thus improving the film coverage. Perovskite solar cells with the polymer network exhibit improved efficiency and reproducibility (0.72% standard deviation). Moreover, the device demonstrates excellent robustness against moisture and oxygen, and maintains 90% of its initial power conversion efficiency (PCEs) after aging 4 months in ambient conditions. The conception of polymer incorporation into inorganic perovskite films paves a way to further increase the performance, stability and reproducibility of inorganic perovskite devices.