Developing metal–halide perovskite nanocrystals (NCs) has attracted great interest due to its potential application in optoelectronic devices. Herein, for the first time we report the facile synthesis of Fe3+-doped cesium lead chloride (CsPbCl3) perovskite NCs along with their exciton relaxation dynamics. Efficient energy transfer occurs from host (CsPbCl3) exciton to Fe3+ dopant, leading to pink-colored dual emission consisting of blue from CsPbCl3 exitonic peak (410 nm) and red from Fe-dopant state (584 nm). Interestingly, Fe-doping is found not only to enhance the photoluminescence quantum yield from 1.85 to 4.32% but also to improve the homogeneity of size and cubic shape of NCs as observed by electron microscopy. Ultrafast transient absorption studies and global fitting analysis reveal the impact of Fe-doping on the exciton relaxation dynamics, where the efficient energy transfer from host exciton to Fe3+ with the lifetime of 135 ps is identified. Another highlighted feature of Fe-doped NCs is its high stability over 30 days and mostly intact intensity up to ∼50 °C. The results provide unique insights into the dual emission properties of Fe-doped CsPbCl3 perovskite NCs, which is an important aspect for high-performance perovskite devices.

Herein, we have reported two benzothiazole-linked covalent organic framework nanostructures (BTZ-BCA-COF and BTZ-TPA-COF), which have been prepared via a highly efficient one-pot, multicomponent transition-metal-free C−H functionalization and oxidative annulation synthetic strategy and employing elemental sulfur as one of the key components. These prepared COFs are highly crystalline in nature, have high surface area, and are chemically stable. These COFs exhibit light-harvesting capacity as a photosensitizer for visible-light-assisted "carbon−boron" bond cleavage with a high functional group tolerance of the substrates. In order to acquire in-depth understanding about the mechanistic pathway involved and for comparison in photocatalytic performance, we have performed in situ electron paramagnetic resonance and studies. Our contribution sheds light on exploration of elemental sulfur to extended π-conjugation network-based photocatalysts, followed by instigating their structural uniqueness− photocatalytic activity relationship.

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