Cubic phase CsPbI 3 (α-CsPbI 3 ) perovskite quantum dots (QDs) have received extensive attention due to their all-inorganic composition and suitable band gap (1.73 eV). However, α-CsPbI 3 QDs might convert to δ-CsPbI 3 (orthorhombic phase with indirect band gap of 2.82 eV) due to easy loss of surface ligands. In addition, commonly used long-chain ligands (oleic acid, OA, and oleylamine, OLA) hinder efficient charge transport in optoelectronic devices. In order to relieve these drawbacks, OA, OLA, octanoic acid, and octylamine are used as capping ligands for synthesizing high-quality α-CsPbI 3 QDs. The results indicate that these QDs exhibit excellent optical properties and long-term stability compared to QDs capped only with OA and OLA. Moreover, QDs with shorter ligands exhibit an enhanced charge transport rate, which improves the power conversion efficiency of photovoltaic devices from 7.76% to 11.87%. obtained a solar cell based on C8/C18-CsPbI 3 QDs with a PCE of 11.87%. The PCE produced by this solar cell is much higher than that of devices based on C18-CsPbI 3 QDs (7.76%).

All-inorganic α-CsPbI 3 perovskite quantum dots (QDs) are attracting high interest as solar cell absorbers due to their appealing light harvesting properties and enhanced stability due to the absence of volatile organic constituents. Moreover, ex situ synthesized QDs significantly reduce the variability of the perovskite layer deposition process. However, it is highly challenging to incorporate α-CsPbI 3 QDs into mesoporous TiO 2 (m-TiO 2), which constitutes the best performing electron transport material in state-of-the-art perovskite solar cells. Herein, the m-TiO 2 surface is engineered using an electron-rich cesium-ion containing methyl acetate solution. As one effect of this treatment, the solid-liquid interfacial tension at the TiO 2 surface is reduced and the wettability is improved, facilitating the migration of the QDs into m-TiO 2. As a second effect Cs + ions passivate the QD surface and promote the charge transfer at the m-TiO 2 /QD interface, leading to an enhancement of the electron injection rate by a factor of three. In combination with an ethanol-environment smoothing route significantly reducing the surface roughness of the m-TiO 2 /QD layer, optimized devices exhibit highly reproducible power conversion efficiencies exceeding 13%. The best cell with an efficiency of 14.32% (reverse scan) reaches a short-circuit current density of 17.77 mA cm −2 , which is an outstanding value for QD-based perovskite solar cells.

Considering the ever‐growing climatic degeneration, sustainable and renewable energy sources are needed to be effectively integrated into the grid through large‐scale electrochemical energy storage and conversion (EESC) technologies. With regard to their competent benefit in cost and sustainable supply of resource, room‐temperature sodium‐ion batteries (SIBs) have shown great promise in EESC, triumphing over other battery systems on the market. As one of the most fascinating cathode materials due to the simple synthesis process, large specific capacity, and high ionic conductivity, Na‐based layered transition metal oxide cathodes commonly suffer from the sluggish kinetics, multiphase evolution, poor air stability, and insufficient comprehensive performance, restricting their commercialization application. Here, this review summarizes the recent advances in layered oxide cathode materials for SIBs through different optimal structure modulation technologies, with an emphasis placed on strategies to boost Na+ kinetics and reduce the irreversible phase transition as well as enhance the store stability. Meanwhile, a thorough and in‐depth systematical investigation of the structure–function–property relationship is also discussed, and the challenges as well as opportunities for practical application electrode materials are sketched. The insights brought forward in this review can be considered as a guide for SIBs in next‐generation EESC.

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