Search

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. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have developed rapidly in recent years due to their excellent photoelectric properties. Among them, lead‐based perovskite photovoltaics have shown great potential for both outdoor and indoor applications, whose power conversion efficiency and stability are much higher than that of lead‐free PSCs. However, based on results of in vivo animal studies, Kyoto Encyclopedia of Genes and Genomes annotations and pathway analysis of microbiota and metabolites influenced by lead, it has been proved that lead exposure from PSCs probably causes systematic toxicity to human body. For the purpose of reducing lead leakage, some methods mainly based on polymer resin protective layers and self‐healing encapsulation have been introduced, which can increase lead capture rate up to 95% under harsh conditions. Eventually, the devices will still face damage and obsolescence, accompanied by lead leakage into the environment. Comprehensive recycling strategies are necessary to solve this problem from the root and also shorten the energy payback time for further transformation and upgrading of green energy. The vertical and in‐depth collaborative strategy for lead leakage prevention and comprehensive recycling would provide an environmentally‐friendly guarantee for the final large‐scale market of perovskite photovoltaics. [ABSTRACT FROM AUTHOR]