For emerging perovskite quantum dots (QDs), understanding the surface features and their impact on the materials and devices is becoming increasingly urgent. In this family, hybrid FAPbI 3 QDs (FA: formamidium) exhibit higher ambient stability, nearinfrared absorption and sufficient carrier lifetime. However, hybrid QDs suffer from difficulty in modulating surface ligand, which is essential for constructing conductive QD arrays for photovoltaics. Herein, assisted by an ionic liquid formamidine thiocyanate, we report a facile surface reconfiguration methodology to modulate surface and manipulate electronic coupling of FAPbI 3 QDs, which is exploited to enhance charge transport for fabricating high-quality QD arrays and photovoltaic devices. Finally, a record-high efficiency approaching 15 % is achieved for FAPbI 3 QD solar cells, and they retain over 80 % of the initial efficiency after aging in ambient environment (20-30 % humidity, 25 °C) for over 600 h.

Lanthanide ions (Yb3+ or Er3+) alloying of CsPb(Cl1‐xBrx)3 quantum dots (QDs) to emit approaching 1000 nm show promise in near‐infrared light‐emitting diodes (NIR‐LEDs). High Yb3+ alloying ratio increases the electroluminance efficiency of emission at 990 nm and enables high external quantum efficiency (EQE) of NIR‐LEDs, however, the high alloying ratio also results in inferior material stability and PLQY drop because of Yb3+‐induced nanocrystal precipitation. This study finds that the heavy alloying of Yb3+ ions causes lattice distortion and coherent energy reduction of Yb3+: CsPb(Cl1‐xBrx)3 QDs, induced by two Yb3+ ions replacing three Pb2+, which leads to the collapse of the octahedral structure in ambient conditions. It posits that spontaneous monovalent ion (Na+) alloying can address the trade‐off between material stability and emission intensity. The Na+ occupies the vacancy of Pb2+ ions, relaxing the distortion in the lattice and improving the phase stability of octahedral structure, and this optimized structure in turn allows a higher Yb3+ alloying ratio. Stability measurements show that the Na+/Yb3+ co‐alloyed films show ten‐fold higher material stability and 2.0‐fold emission efficiency related to controls. It reports that as a result Na+/Yb3+ co‐alloyed NIR‐LEDs have an EQE of 6.4% at 990 nm, which is among the highest perovskite NIR‐LEDs beyond 950 nm.

Organic–inorganic formamidinium lead triiodide (FAPbI3) hybrid perovskite quantum dot (QD) is of great interest to photovoltaic (PV) community due to its narrow band gap, higher ambient stability, and long carrier lifetime. However, the surface ligand management of FAPbI3 QD is still a key hurdle that impedes the design of high‐efficiency solar cells. Herein, this study first develops a solution‐mediated ligand exchange (SMLE) for preparing FAPbI3 QD film with enhanced electronic coupling. By dissolving optimal methylammonium iodide (MAI) into antisolvent to treat the FAPbI3 QD solution, the SMLE can not only effectively replace the long‐chain ligands, but also passivate the A‐ and X‐site vacancies. By combining experimental and theoretical results, this study demonstrates that the SMLE engineered FAPbI3 QD exhibits lower defect density, which is beneficial for fabricating high‐quality QD arrays with desired morphology and carrier transport. Consequently, the SMLE FAPbI3 QD based solar cell outputs a champion efficiency of 15.10% together with improved long‐term ambient storage stability, which is currently the highest reported value for hybrid perovskite QD solar cells. These results would provide new design principle of hybrid perovskite QDs toward high‐performance optoelectronic application.

The challenge of re-electrification urges the performance improvement in alkali/alkaline metal ion batteries (AMIBs) materials while the traditional research paradigm fully based on experiments and theoretical simulations need massive research...

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