Eco-friendly quantum-dot light-emitting diodes (QLEDs), which employ colloidal quantum dots (QDs) such as InP, and ZnSe, stand out due to their low toxicity, color purity, and high efficiency. Currently, significant advancements have been made in the performance of cadmium-free QLEDs. However, several challenges persist in the industrialization of eco-friendly QLED displays. For instance, (1) the poor performance, characterized by low photoluminescence quantum yield (PLQY), unstable ligand, and charge imbalance, cannot be effectively addressed with a solitary strategy; (2) the degradation mechanism, involving emission quenching, morphological inhomogeneity, and field-enhanced electron delocalization remains unclear; (3) the lack of techniques for color patterning, such as optical lithography and transfer printing. Herein, we undertake a specific review of all technological breakthroughs that endeavor to tackle the above challenges associated with cadmium-free QLED displays. We begin by reviewing the evolution, architecture, and operational characteristics of eco-friendly QLEDs, highlighting the photoelectric properties of QDs, carrier transport layer stability, and device lifetime. Subsequently, we focus our attention not only on the latest insights into device degradation mechanisms, particularly, but also on the remarkable technological progress in color patterning techniques. To conclude, we provide a synthesis of the promising prospects, current challenges, potential solutions, and emerging research trends for QLED displays.

With the rapid development of lithium batteries, it’s of great significance to ensure the safe use of it. An ultrasound imaging system based on fiber optic ultrasound sensor has been developed to monitor the internal changes of lithium batteries. Based on Fabry-Perot interferometer (FPI) structure which is made of a glass plate and an optical fiber pigtail, the ultrasound imaging system possesses a high sensitivity of 558 mV/kPa at 500 kHz with the noise equivalent pressure (NEP) of only 63.5 mPa. For the frequency response, the ultrasound sensitivity is higher than 13.1 mV/kPa within the frequency range from 50 kHz to 1 MHz. Meanwhile, the battery imaging system based on the proposed sensor has a superior resolution as high as 0.5 mm. The performance of battery safety monitoring is verified, in which three commercial lithium-ion ferrous phosphate/graphite (LFP||Gr) batteries are imaged and the state of health (SOH) for different batteries is obtained. Besides, the wetting process of an anode-free lithium metal batteries (AFLMB) is clearly observed via the proposed system, in which the formation process of the pouch cell is analyzed and the gas-related "unwetting" condition is discovered, representing a significant advancement in battery health monitoring field. In the future, the commercial usage can be realized when sensor array and artificial intelligence technology are adopted.