Unlike conventional electrochromic devices, Zinc anode-based electrochromic devices (ZECDs) ensure excellent charge balance between the electrochromic layer and Zn anode during the coloring/bleaching by reversible metal deposition/stripping on the Zn anode. Meanwhile, the inherent potential difference between the metal anode and the electrochromic layer can drive the spontaneous coloration/bleaching of ZECDs, featuring energy retrieval functionality. This review discusses the working mechanisms, performance indexes of ZECDs, and the impact of material selection on ZECD performance. Furthermore, we comprehensively summarize the latest research progress of ZECDs in energy storage, smart windows, and multicolor displays. We argue that using high-transparency zinc mesh, additive manufacturing processes, and self-healing electrochromic materials can significantly advance the commercialization of large-area ZECDs. Finally, “electrode-free” device structures, renewable or replaceable electrolytes, and strategies to suppress zinc dendrites are prospected to overcome cost-effectiveness and lifespan issues of ZECDs. This review aims at enabling more efficient and advanced ZECDs for multifunctional applications.

Carbon dots (CDs) with solvatochromic emission colors in different solvents have attracted much attention as a new class of luminescent nanomaterial owing to their facile synthesis and low production cost. In this work, we prepared two kinds of CDs with solvatochromic emissions: green emission CDs (G-CDs) and multicolor emission CDs (M-CDs). G-CDs synthesized from o-phenylenediamine exhibited weak photoluminescence emission (quantum yield 2.8%-6.1%) and 39 nm solvatochromic shifts (492-531 nm). In contrast, M-CDs prepared from o-phenylenediamine and 4-aminophenol showed 87 nm solvatochromic shift range (505-592 nm) and much higher photoluminescence quantum yield (18.4%-32.5%). The two CDs exhibited different emission, absorption, and photoluminescence lifetime. The origin of solvatochromic shifts and the formation mechanism of CDs were demonstrated by analyzing the structures and compositions of two CDs. High percentages of pyrrolic nitrogen and amino nitrogen make wider solvatochromic shifts and higher quantum yields. The results were well supported by density functional theory calculations. This effective strategy to expand solvatochromic shift range and improve quantum yields could open a new window to prepare satisfied solvatochromic carbon dots.